一种改进的多学习教与学优化算法

针对传统教与学算法在解决复杂多峰函数优化问题时,具有局部最优且搜索开发能力较差的缺点,提出了一种改进的多学习教与学优化算法,新算法为学员的每一维加入不同的教学因子,设计了基于学员均值比较的教师选择策略和向教师及学员学习的多学习策略。基于多个单峰和多峰函数的仿真结果表明,新算法跟传统的、改进的教与学算法相比,在稳定性、寻优精度和收敛速度方面更具优势。     

The theory of neighbourhood decline due to pariah land uses: Regaining control of the downward cycle

Some neighbourhood environments have become dumping grounds for locally unwanted land uses (LULUs) that middle-class Americans do not want near their homes. LULUs may combine with other pariah land uses to collectively undermine the quality of the local environment, reduce investment, government services, the proportion of middle-income people and associated businesses. As important neighbourhood attributes are lost, illegal activities, derelict structures, trash-strewn lots and the concentration of poor and unhealthy people may increase. This paper describes the theory behind the impact of pariah land uses through examples of the downward spiral experienced by Camden, New Jersey and the south Bronx, New York. It then documents the experience of one community, Elizabethport, New Jersey, in reversing that downward spiral. Success in Elizabethport came from the synergistic activities of local, state and federal governments, community groups, and not-for-profit organizations as they struggled to regain control through local environmental management, rebuilding, and reducing crime. Social capital was also strengthened by using a local community health concern—that of childhood asthma. Efforts to reverse the downward spiral of urban decay from pariah land uses should be multi-faceted, spurred by local efforts that address local concerns.     

Magnesium-rich minerals in sediment and suspended particulates of South Florida water bodies: implications for turbidity

Fine sediments in shallow water bodies such as Lake Okeechobee are prone to resuspension. Predominantly inorganic "mud" sediment that covers approximately 670 km2 of the lake has been recognized as a persistent source of turbidity. The objective of this study was to determine if mineral components of sediments in Lake Okeechobee and water conveyances of the northern Everglades also occur as suspended sediment and hence constitute a potential abiotic contributor to turbidity. Sediment samples were collected from nine stations within the lake and eight locations north of Water Conservation Area 2A in the Everglades. Water samples were also collected at selected locations. The silt and clay mineralogy of sediment and suspended particles was determined using X-ray diffraction, thermogravimetry, scanning-electron microscopy, energy-dispersive X-ray elemental microanalysis, and high-resolution transmission-electron microscopy. Clay fractions of the lake sediment contained the Mg silicate minerals sepiolite and palygorskite, along with smectite, dolomite, calcite, and kaolinite. Sediment silt fractions were dominated by carbonates and/or quartz, with smaller amounts of Ca phosphates and sepiolite. Mineralogy of the mud sediment was similar to that reported for geologic phosphate deposits. This suggests that the mud sediment might have accumulated by stream transport of minerals from these deposits. Suspended solids and mud-sediment mineralogy were similar, except that smectite was more abundant in suspended solids. Everglade samples also contained Mg-rich minerals. The small size, low density, and fibrous or platy nature of the prevalent mud sediment minerals make them an abiotic, hydrodynamically sensitive source of persistent turbidity in a shallow lake. Mitigation efforts focused exclusively on P-induced biogeochemical processes do not address the origin or effects of these minerals. Ecological management issues such as turbidity control, P retention, geologic P input, and suitability of dredging are related to mud-sediment properties and provenance.     

Substrate organic matter to improve nitrate removal in surface-flow constructed wetlands

A wetland mesocosm experiment was conducted in eastern North Carolina to determine if organic matter (OM) addition to soils used for in-stream constructed wetlands would increase NO3--N treatment. Not all soils are suitable for wetland substrate, so OM addition can provide a carbon and nutrient source to the wetland early in its development to enhance denitrification and biomass growth. Four batch studies, with initial NO3--N concentrations ranging from 30 to 120 mg L-1, were conducted in 2002 in 21 surface-flow wetland mesocosms. The results indicated that increasing the OM content of a Cape Fear loam soil from 50 g kg-1 (5% dry wt.) to 110 g kg-1 (11% dry wt.) enhanced NO3--N wetland treatment efficiency in spring and summer batch studies, but increases to 160 g kg-1 (16% dry wt.) OM did not. Wetlands constructed with dredged material from the USACE Eagle Island Confined Disposal Facility in Wilmington, NC, with initial OM of 120 g kg-1 (12% dry wt.), showed no improvement in NO3--N treatment efficiency when increased to 180 g kg-1 (18% dry wt.), but did show increased NO3--N treatment efficiency in all batch studies when increased to 220 g kg-1 (22% dry wt.). Increased OM addition and biosolids to the Cape Fear loam and dredged material blends significantly increased biomass growth in the second growing season when compared to no OM addition. Results of this research indicate that increased OM in the substrate will reduce the area required for in-stream constructed wetlands to treat drainage water in humid regions. It also serves as a demonstration of how dredged material can be used successfully in constructed wetlands, as an alternative to costly storage by the USACE.     

Postemergence Control of Microstegium vimineum on Riparian Restoration Sites with Aquatic‐Use Registered Herbicides

Microstegium vimineum is an invasive grass introduced from Asia that has spread throughout riparian areas of the eastern United States threatening native riparian vegetation. Postemergence (POST) herbicides registered for aquatic use were evaluated for control of M. vimineum on two riparian restoration sites in the Piedmont and Upper Coastal Plain of North Carolina. This study found that standard and lower than standard rates of diquat, fluridone, flumioxazin, glyphosate, imazamox, and imazapyr reduced weed stem density and biomass at 6 and 30 weeks after treatment (WAT). Both rates of bispyribac and penoxsulam provided less control of M. vimineum. Visual ratings showed both rates of diquat, flumioxazin, imazamox, and imazapyr controlled 63‐100% of M. vimineum at 6 WAT and 84‐100% at 30 WAT. Fluridone and glyphosate provided slightly less control. Bispyribac and penoxsulam treatments provided less control at 6 and 30 WAT compared to the other treatments. Plots treated with both rates of diquat, flumioxazin, imazamox, and imazapyr were nearly devoid of all vegetation at 30 WAT. Recommendations include POST application of lower than standard rates of diquat, flumioxazin, fluridone, glyphosate, imazamox, and imazapyr on riparian restoration sites infested with M. vimineum. Immediate vegetation management measures including temporary and permanent plant cover should be employed on treated sites where weeds are completely eradicated to prevent erosion.     

Effects of experience and avpr1a microsatellite length on parental care in male prairie voles (Microtus ochrogaster)

Pair-bonded males often make substantial contributions to the care of their offspring. Male parental behavior may be affected by a range of factors, including previous experience (parental or alloparental), genetic influences, and contributions by the female partner. Previous studies have shown that a microsatellite polymorphism in the regulatory region of the avpr1a gene influences aspects of paternal behavior in male prairie voles (Microtus ochrogaster). Specifically, males with longer avpr1a microsatellites groomed offspring more than did males with shorter avpr1a microsatellites. Previous experience with alloparental care also appears to influence subsequent paternal care in prairie voles. We investigated the influence of avpr1a microsatellite length and previous parental experience on paternal behavior in prairie voles two generations from the field and specially bred to exaggerate differences in avpr1a microsatellite length. We found that avpr1a microsatellite length alone did not affect any of the paternal behaviors that we measured. In contrast, males differed in parental behavior between first and second litters. Regardless of avpr1a microsatellite length, males licked/groomed the second litter less, and retrieved pups more quickly during the second compared to the first litter. Our results show that previous paternal experience may play a more important role than the length of the microsatellite in the regulatory region of the avpr1a gene in influencing paternal care.