On the Origin of the Quantum Rules for Identical Particles

We present a proof of the Symmetrization Postulate for the special case of noninteracting, identical particles. The proof is given in the context of the Feynman formalism of Quantum Mechanics, and builds upon the work of Goyal, Knuth and Skilling (Phys. Rev. A 81, 022109 (2010)), which shows how to derive Feynman's rules from operational assumptions concerning experiments. Our proof is inspired by an attempt to derive this result due to Tikochinsky (Phys. Rev. A 37, 3553 (1988)), but substantially improves upon his argument, by clarifying the nature of the subject matter, by improving notation, and by avoiding strong, abstract assumptions such as analyticity.Comment: 8 pages, all figures embedded as TikZ. V2 clarified wording from V1 in response to reviewe

The influence of soil types and fertilizers on growth parameters of three goatgrass species (Aegilops) from the coastal plains of Israel: A. sharonensis Eig, A. longissima Schwienf. et Muschl. and A. speltoides Tausch

Three species of goatgrass (Aegilops L.), the wild relative of wheat, grow naturally in the coastal plains of Israel. The distribution and ecological parameters of Aegilops sharonensis were determined by a field survey, while similar information on the other species was obtained from the BioGIS database. The distribution of plants was soil-specific. Sharon goatgrass (A. sharonensis Eig) is endemic to Israel and southern Lebanon's coastal plains, which have been stabilized with dunes and sandy soils. In contrast, slender goatgrass (A. longissima Schwienf. et Muschl.) grows mainly on sandy loam and the truncate goatgrass (A. speltoides Tausch) grows primarily on heavy alluvial soils. The present 4-month study evaluated the affinity between these 3 Aegilops species, the 3 different types of soils and fertilizer application, in buckets. Interestingly, a significant increase in the number and weight of the spikes were observed in fertilized buckets. We could also find that these 3 species preferred heavy alluvial soil over the sands, regardless of the fertilizer treatment. The data suggested that the population of A. sharonensis was limited to the sandy dunes by urbanization along the coastal plane and aggressive competition with the other species. Their more extended root system may adapt A. sharonensis to the deep and salty groundwater that characterizes dunes. It is suggested to keep representatives of the Israeli Aegilops populations in a nature reserve for protection from extinction

Bacterially mediated removal of phosphorus and cycling of nitrate and sulfate in the waste stream of a "zero-discharge" recirculating mariculture system

Simultaneous removal of nitrogen and phosphorus by microbial biofilters has been used in a variety of water treatment systems including treatment systems in aquaculture. In this study, phosphorus, nitrate and sulfate cycling in the anaerobic loop of a zero-discharge, recirculating mariculture system was investigated using detailed geochemical measurements in the sludge layer of the digestion basin. High concentrations of nitrate and sulfate, circulating in the overlying water (~15 mM), were removed by microbial respiration in the sludge resulting in a sulfide accumulation of up to 3 mM. Modelling of the observed S and O isotopic ratios in the surface sludge suggested that, with time, major respiration processes shifted from heterotrophic nitrate and sulfate reduction to autotrophic nitrate reduction. The much higher inorganic P content of the sludge relative to the fish feces is attributed to conversion of organic P to authigenic apatite. This conclusion is supported by: (a) X-ray diffraction analyses, which pointed to an accumulation of a calcium phosphate mineral phase that was different from P phases found in the feces, (b) the calculation that the pore waters of the sludge were highly oversaturated with respect to hydroxyapatite (saturation index = 4.87) and (c) there was a decrease in phosphate (and in the Ca/Na molar ratio) in the pore waters simultaneous with an increase in ammonia showing there had to be an additional P removal process at the same time as the heterotrophic breakdown of organic matter

Physiological responses and productivity of the seaweed Ulva ohnoi (Chlorophyta) under changing cultivation conditions in pilot large land-based ponds

Land based intensive cultivation systems have been proposed as an ideal option for the commercial production of high value products from seaweeds. However, many cultures on Ulva and other seaweeds are based on relatively small-scale facilities. The high variability of culture conditions can strongly affect the physiological performance of seaweeds, but few studies examine their phenotypic plasticity by integrating critical biological descriptors, e.g. photobiology, oxidative stress, nutrient acquisition. The purpose of this study was to determine the physiological plasticity and growth of Ulva ohnoi during its cultivation in land-based 40 m3 ponds. Through an entire culti-vation cycle (four-weeks), photosynthesis, respiration, pigments, antioxidant capacity and nutrient content were measured. Light, temperature, pH, and dissolved inorganic nitrogen (DIN) were simultaneously monitored in seawater. Additionally, the N-uptake kinetics of U. ohnoi were examined in the laboratory in order to explain the efficiency of the seaweed biomass for DIN-incorporation in the ponds after fertilization. Generally, the gradual increase in seaweed density throughout the cultivation period was directly associated to a drop in light avail-ability and dissolved inorganic carbon (i.e. higher pH) within the ponds. These changes in cultivation conditions were related to a reduction of photosynthetic capacities, nutrient content and growth of U. ohnoi. N-uptake kinetics of U. ohnoi and the behavior of DIN within the ponds after fertilization, indicated that U. ohnoi was able to incorporate ammonium more efficiently than nitrate, and the presence of the former likely inhibits nitrate acquisition. The understanding of the capacity of U. ohnoi to acclimate to the extreme changing culture condi-tions, could be applied to improve its productivity and chemical composition.En prens

Effect of salinity and nitrogen fertilization levels on growth parameters of Sarcocornia fruticosa, Salicornia brachiata, and Arthrocnemum macrostachyum

Salinity negatively influences crop growth, but several salt-tolerant plant species (halophytes) are viable crops. Sarcocornia fruticosa (ecotypes EL and VM) is currently cultivated, but there is demand for new crop candidates and higher biomass production. Salicornia brachiata Roxb. and Arthrocneum macrostachyum L. are considered novel crops, and to realize their potential, their response to salinity and nitrogen nutrition was compared to S. fruticosa ecotypes. Experiments revealed that higher N supplemented with lower NaCl significantly increased fresh and dry shoot biomass. Lower biomass was obtained at lower nitrogen supplemented with elevated NaCl, whereas total soluble solids content positively correlated with NaCl fertigation in both Sarcocornia ecotypes. Protein content increased with a lower nitrogen supply. Anthocyanins and oxygen radical absorbance capacity were highest in S. fruticosa EL and A. macrostachyum at higher NaCl supply. The results show that halophytes have a variety of strategies to cope with high NaCl, even between ecotypes of the same species. Notably, repetitive harvesting of S. brachiata delayed flowering enabling year-round biomass production. Additionally, S. brachiata accumulated higher biomass than Sarcocornia VM when grown in a greenhouse at higher radiation than in a growth room and strongly supports its inclusion as a cash-crop halophyte.info:eu-repo/semantics/publishedVersio

Ecological and morphological features of Amyloodinium ocellatum occurrences in cultivated gilthead seabream Sparus aurata L.; A case study

Understanding the patterns of occurrence of the ectoparasite Amyloodinium ocellatum and the conditions that result in its maintenance at non-dangerous levels for gilthead seabream Sparus aurata could be very useful, since outbreaks of heavy infestation by this parasitic dinoflagellate can cause severe mortality in temperate aquaculture. We have evaluated the interactions between A. ocellatum and related environmental variables for the first time. Biotic and abiotic parameters of water quality in production ponds from a temperate aquaculture (Sado Estuary, Portugal) were monitored and subsequently analysed. Dissolved oxygen, water temperature, pH, phytoplankton biomass and salinity were closely related to A. ocellatum occurrences; dissolved oxygen, water temperature, pH and phytoplankton biomass had significant negative relationships with A. ocellatum trophonts, while salinity had a significant positive relationship with A. ocellatum trophonts in fish gills. Phytoplankton biomass was significantly correlated with increases of dissolved oxygen in production ponds. An increase of rate of water renewal increased salinity, due to persistence of low water levels in production ponds during the water renewal procedure. Salinity negatively affected phytoplankton biomass and consequently the level of dissolved oxygen, raising the probability of A. ocellatum occurrences. Fish biomass in production ponds was correlated with the average and the maximum number of trophonts found in fish gills, highlighting the importance of defining stocking levels and production values in ponds. The present results help to improve understanding of the interactions between biotic and abiotic variables, fish farm management practices and parasite incidence in temperate terrestrial pond aquaculture. A morphological feature of the A. ocellatum tomonts cells in division phase, collected from the most infected fish gills, is discussed. We also give a description and illustration of the phases of the A. ocellatum life cycle

Nitrogen uptake and internal recycling in Zostera marina exposed to oyster farming: eelgrass potential as a natural biofilter

Oyster farming in estuaries and coastal lagoons frequently overlaps with the distribution of seagrass meadows, yet there are few studies on how this aquaculture practice affects seagrass physiology. We compared in situ nitrogen uptake and the productivity of Zostera marina shoots growing near off-bottom longlines and at a site not affected by oyster farming in San Quintin Bay, a coastal lagoon in Baja California, Mexico. We used benthic chambers to measure leaf NH4 (+) uptake capacities by pulse labeling with (NH4)-N-15 (+) and plant photosynthesis and respiration. The internal N-15 resorption/recycling was measured in shoots 2 weeks after incubations. The natural isotopic composition of eelgrass tissues and vegetative descriptors were also examined. Plants growing at the oyster farming site showed a higher leaf NH4 (+) uptake rate (33.1 mmol NH4 (+) m(-2) day(-1)) relative to those not exposed to oyster cultures (25.6 mmol NH4 (+) m(-2) day(-1)). We calculated that an eelgrass meadow of 15-16 ha (which represents only about 3-4 % of the subtidal eelgrass meadow cover in the western arm of the lagoon) can potentially incorporate the total amount of NH4 (+) excreted by oysters (similar to 5.2 x 10(6) mmol NH4 (+) day(-1)). This highlights the potential of eelgrass to act as a natural biofilter for the NH4 (+) produced by oyster farming. Shoots exposed to oysters were more efficient in re-utilizing the internal N-15 into the growth of new leaf tissues or to translocate it to belowground tissues. Photosynthetic rates were greater in shoots exposed to oysters, which is consistent with higher NH4 (+) uptake and less negative delta C-13 values. Vegetative production (shoot size, leaf growth) was also higher in these shoots. Aboveground/belowground biomass ratio was lower in eelgrass beds not directly influenced by oyster farms, likely related to the higher investment in belowground biomass to incorporate sedimentary nutrients

Flavonoids, Phenolics, and Antioxidant Capacity in the Flower of Eriobotrya japonica Lindl.

Flavonoids and phenolics are abundant in loquat flowers. Methanol had the highest extraction efficiency among five solvents, followed by ethanol. Considering the safety and residue, ethanol is better as extraction solvent. The average content of flavonoids and phenolics of loquat flower of five cultivars were 1.59 ± 0.24 and 7.86 ± 0.87 mg/g DW, respectively, when using ethanol as extraction solvent. The contents of both bioactive components in flowers at different developmental stages and in the various flower tissues clearly differed, with the highest flavonoids and phenolics content in flowers of stage 3 (flower fully open) and petal, respectively. The antioxidant capacity was measured using FRAP, DPPH, and ABTS methods. The values of ABTS method was highest, followed by DPPH, the lowest was FRAP, when using vitamin C equivalent antioxidant capacity (VCEAC) as unit. Correlation analysis showed that the ABTS method showed the highest correlation coefficients with flavonoids and phenolics, i.e., 0.886 and 0.973, respectively