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Plutonium (Pu), a key contaminant at sites associated with the manufacture of nuclear weapons and with nuclear-energy wastes, can be precipitated to “immobilized” plutonium phases in systems that promote bioreduction. Ferric iron (Fe3+) is often present in contaminated sites, and its bioreduction to ferrous iron (Fe2+) may be involved in the reduction of Pu to forms that precipitate. Alternately, Pu can be reduced directly by the bacteria. Besides Fe, contaminated sites often contain strong complexing ligands, such as nitrilotriacetic acid (NTA). We used biogeochemical modeling to interpret the experimental fate of Pu in the absence and presence of ferric iron (Fe3+) and NTA under anaerobic conditions. In all cases, Shewanella alga BrY (S. alga) reduced Pu(V)(PuO2 +) to Pu(III), and experimental evidence indicates that Pu(III) precipitated as PuPO4(am). In the absence of Fe3+ and NTA, reduction of PuO2 + was directly biotic, but modeling simulations support that PuO2 + reduction in the presence of Fe3+ and NTA was due to an abiotic stepwise reduction of PuO2 + to Pu4+, followed by reduction of Pu4+ to Pu3+, both through biogenically produced Fe2+. This means that PuO2 + reduction was slowed by first having Fe3+ reduced to Fe2+. Modeling results also show that the degree of PuPO4(am) precipitation depends on the NTA concentration. While precipitation out-competes complexation when NTA is present at the same or lower concentration than Pu, excess NTA can prevent precipitation of PuPO4(am).  相似文献   

3.
Acidification of lakes takes place when pH of rainwater is less than 4.5 and the catchments lie on sensitive geology. Both conditions are met for most lakes in Bohemia and Slovakia. Since 1978 we have studied mountain lakes in the Sumava and in the High Tatra Mountains. In Šumava the three lakes under study are of glacial origin. The catchments are small, with steep sides covered by spruce. The bedrocks are biotite-rich paragneiss, together with gneiss, quartzite and granite. In summer 1936 surface pH was 5.7–6.9 in the Lake Čertovo and 6.9–7.0 in the Lake Černé. Now the pH values are 4.3–4.8 in the two lakes and in the Lake Prášilské as well. Old reports on zooplankton are from the years 1871, 1892–96, 1935–37, 1947 and 1960. Since 1979 we have not found any planktonic Crustacea in the lakes Černé and Čertovo. Lake Prášilské is inhabited by Daphnia longispina and Cyclops abyssorum. In July 1989 the pH values were 4.4, 4.7 and 4.7, concentrations of labile monomeric Al were 0.83, 0.68 and 0.24 mg l-1 in the lakes Čertovo, Černé and Prašilské, respectively. High levels of toxic Al compounds might be responsible for the extinction of planktonic Crustacea in the lakes Čertovo and Černé. All the three lakes are void of fish at present. In the High Tatra Mts. we examined more than 40 lakes above timberline in altitudes 1612–2145 m. They are all clearwater, naturally fishless lakes. The bedrock is granite. Owing to different levels of calcium the lakes are now in different stages of acidification. According to recent changes in the zooplankton they can be divided into three groups: (1) Species composition of planktonic Crustacea has not changed. (2) Planktonic Crustacea were present until 1973 but are absent now. (3) From the original species of Crustacea only Chydorus sphaericus is present. The three groups are well separated along the gradients of calcium, ANC and pH. They can be identified with the Henriksen's bicarbonate (our group 1), intermediate (our group 2) and acid (our group 3) lakes. We suppose that in the process of acidification the lakes of the group (2) have been shifted from oligotrophy to ultraoligotrophy.  相似文献   

4.
Comparative ecological and aerobiological analyses of ornamental urban flora in the cities of Córdoba (Spain) and Ascoli Piceno (Italy) identified a group of plants with allergenic pollen whose behaviour is influenced by a number of factors. The geographical position and the resulting climate of both cities favoured the presence of Mediterranean species. In Córdoba, strongly allergenic evergreens introduced during the Moorish period predominated (Cupressus sempervirens, among others), while in the urban area of Ascoli Piceno, Pinaceae were abundant. In both cities, many species of American origin have been introduced for aesthetic reasons, contributing to an increase in the overall allergenicity of urban greenery. The pollen spectrum differed between the two cities: airborne Oleaceae and Cupressaceae pollen abounded in Córdoba, whilst allergenic pollen from surrounding natural environments (Corylaceae) predominated in Ascoli Piceno. These results pointed to a large number of potentially allergenic species in cities, thus highlighting the importance of greater ecological and aerobiological knowledge of allergenic species of urban ornamental flora. Avoidance of more allergenic species when planning new urban green areas could ensure healthier environments for pollen-allergy sufferers.  相似文献   

5.
The European endemic Erebia oeme (Hübner [1804]) (Lepidoptera: Nymphalidae: Satyrinae) is discovered in the Carpathian Chain, from where it was considered to be absent. The single population found is situated in the southern part of the Romanian Carpathians (Retezat Mountains), where it flies sympatrically and synchronically with Erebia medusa ([Denis & Schiffermüller] 1775). The similar external morphology of these two species probably caused E. oeme to be overlooked in the Carpathians, leading to an unexpected information gap in the otherwise thoroughly studied European continent. The morphology of the Romanian specimens is compared to populations from the rest of the species’ range and to E. medusa. In addition, we tested DNA barcoding as a method to discriminate between these species and confirmed that it represents an effective identification tool for the taxa involved. The habitat of E. oeme, adults of both sexes and their genitalia are illustrated in comparison with E. medusa. Based on the study of several collections, we show that E. oeme is likely to be extremely local in the Carpathians and provide arguments to consider the species as vulnerable in Romania.  相似文献   

6.
Since nine patients with infantile liver cirrhosis or hepatopathy associated with the Pi ZZ phenotype had been observed in recent years in the Children's Hospital of the University of Innsbruck, Tyrol, the distribution of the Pi types and the PiM subtypes was determined in the Tyrolean population. Apparently healthy blood donors (868) from different regions of Tyrol were examined. Isoelectricfocusing was used for classification of Pi types. The frequency of the allele PiZ was 0.0138, which corresponded to the range observed in other Middle European populations. The frequencies for the suballeles of PiM were PiM1 = 0.7062, PiM2 = 0.1480, and PiM3 = 0.1037. PiS had a frequency of 0.0225, the other rare alleles occurred with a combined frequency of 0.0058.  相似文献   

7.
《Ethnos》2012,77(2):177-202
Drawing on first-hand ethnographical data from the Xang"ô, an Afro-Brazilian Cult in Recife (Brazil), I defend that learning possession means in the first place to learn to identify and react to specific emotional states in accordance with cultural representations and expectations. This emotional learning would take place through two potential processes during ritual activity. On the one hand a powerful coupling process linking “uncanny” body arousals to mythological imagination captured by the highly evocative content of songs, invocations, objects and substances during ritual activity. Ritual features such as archetypality, rigidity, regularity, redundancy and spatial and temporal delimitation are propitious for eliciting and “boosting” this coupling process. On the other hand, a social referencing process through which emotional and behavioral reactions towards possessed persons act for novices as reliable indicators of how to recognize, interpret and regulate their own emotional states associated with possession. With growing familiarity with possession's conceptual and experiential background, their emotional reactions might evolve from largely undifferentiated arousal states to “orixa´-specific” somatic signature and novices might become more active towards their own possession. They also demonstrate an increasing sensitivity to isolated emotional elicitors of possession as well as a better control over their emotional reaction.  相似文献   

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We assayed a variety of tick (Amblyomma hebraeum Koch; Acari, Ixodidae) tissues for a number of amino acids throughout the feeding and early reproductive periods. Our HPLC assay could detect as little as 2–5 pmol per sample of the following: GABA, glycine, serine, glutamine, alanine, taurine, glutamate and aspartate. All of these amino acids could be detected in the salivary gland, synganglion (=total CNS in acarines), haemolymph, Gené's organ, seminal receptacle and ovary. GABA reached high levels in the salivary gland of freshly engorged ticks (685 nmol g-1) and in the synganglion it exceeded 1000 nmol g-1 throughout most of the feeding cycle and the first week post-engorgement. GABA also reached a peak titre in the haemolymph of 40 nmol ml-1. Taurine levels peaked at 1065 nmol g-1 in the salivary gland from large partially fed ticks. Glutamate and aspartate were likewise found in the salivary gland and synganglion at high concentrations. For most of the amino acids there is insufficient information to correlate these titres (and fluctuations of titres) to neuromodulatory functions. It is possible, however, that the high GABA titre in the salivary gland of engorged ticks is correlated with an augmented level of fluid secretion.Deceased: Department of Pharmacology, University of Alberta, Edmonton, Alberta, Canada, T6G 2E9.  相似文献   

11.
To find suitable candidates for biological control of the bulb mite, Rhizoglyphus robini Claparède (Acari: Astigmata) on lilies, exploration was undertaken in areas where the bulb mite is an established pest (The Netherlands, Taiwan and Japan). Among the predators, found in association with R. robini in the field and under storage conditions, mesostigmatic mites predominate. The most abundant species were Hypoaspis aculeifer (Canestrini), Lasioseius bispinosus Evans and Parasitus fimetorum (Berlese). These predators appeared to feed and reproduce on a diet of exclusively R. robini and they were able to control the bulb mite in small-scale population experiments initiated with a 1:20 predator-prey ratio. Under laboratory conditions corresponding to lily bulb propagation (lily scales mixed with vermiculite and stored at 23°C and >90% RH) the laelapid mite, H. aculeifer, was the most effective predator; the ascid predator, L. bispinosus, was much less effective, but being relatively small and being successful in attacking the juvenile stages of the bulb mite it may be better able to search for bulb mites hidden inside the lily bulb. The parasitid predator, P. fimetorum, failed to control the bulb mite when vermiculite was used as a medium, but turned out to suppress this prey when peat was used instead. Various strains of H. aculeifer or closely related species were compared with respect to their impact and performance on bulb mites as prey: two Dutch strains, one obtained from Breezand and the other from 'tZand, a Taiwanese strain, a German strain that in contrast to the previously mentioned strains was not collected from lily bulbs, but from agricultural areas near Bremen and, in addition, a Canadian strain of a related species (Hypoaspis miles Berlese), known to control sciarid fly larvae. These comparative experiments showed that H. miles died out without noticeable impact on the bulb mite population whereas all strains of H. aculeifer were able to suppress the bulb mites to very low numbers. However, the numerical responses of the H. aculeifer strains differed in that those collected in association with the pest (Breezand > Taiwan > 'tZand) were superior to the strain from Bremen. These results do not provide support to the Hokkanen and Pimentel hypothesis, which states that predators forming an evolutionary new association with the pest are often more effective in biological control.  相似文献   

12.
W. M. Graham 《Hydrobiologia》2001,451(1-3):97-111
Fisheries resource trawl survey data from the National Marine Fisheries Service from a 11–13-year period to 1997 were examined to quantify numerical and distributional changes of two species of northern Gulf of Mexico scyphomedusae: the Atlantic sea nettle, Chrysaora quinquecirrha (Desor), and the moon jelly, Aurelia aurita (Linné). Trawl surveys were grouped into 10 statistical regions from Mobile Bay, Alabama to the southern extent of Texas, and extended seaward to the shelf break. Records of summertime C. quinquecirrha medusa populations show both an overall numerical increase and a distributional expansion away from shore in the down-stream productivity field of two major river system outflows: Mobile Bay and the Mississippi-Atchafalaya Rivers. In addition, there is a significant overlap between summer C. quinquecirrha and lower water column hypoxia on the Louisiana shelf. In trawl surveys from the fall, A. aurita medusae showed significant trends of numerical increase in over half of the regions analyzed. For both species, there were statistical regions of no significant change, but there were no regions that showed significant decrease in number or distribution. The relationships between natural and human-induced (e.g. coastal eutrophication, fishing activity and hard substrate supplementation) ecosystem modifications are very complex in the Gulf of Mexico, and the potential impact of increased jellyfish populations in one of North America's most valuable fishing grounds is a most critical issue. Several hypotheses are developed and discussed to guide future research efforts in the Gulf of Mexico.  相似文献   

13.

Background

Chronic pancreatitis is an inflammatory disease which is characterized by an irreversible conversion of pancreatic parenchyma to fibrous tissue. Beside obstructive jaundice and pseudocyst formation, about half of the patients need surgical intervention due to untreatable chronic pain during the course of the disease. In most of the patients with chronic pancreatitis, the head of the pancreas is the trigger of the chronic inflammatory process. Therefore, resection of pancreatic head tissue must be the central part of any surgical intervention. However, it is unclear to which extent the surgical procedure must be radical in order to obtain a favourable outcome for the patients.

Design

A single centre randomized controlled, superiority trial to compare two techniques of duodenum preserving pancreatic head resection. Sample size: 65 patients will be included and randomized intraoperatively. Eligibility criteria: All patients with chronic pancreatitis and indication for surgical resection and signed informed consent. Cumulative primary endpoint (hierarchical model): duration of surgical procedure, quality of life after one year, duration of intensive care unit stay, duration of hospital stay. Reference treatment: Resection of the pancreatic head with dissection of the pancreas from the portal vein and transsection of the gland (Beger procedure). Intervention: Partial Resection of the pancreatic head without transsection of the organ and visualization of the portal vein (Berne procedure). Duration: September 2003-October 2007.

Organisation/responsibility

The trial is conducted in compliance with the protocol and in accordance with the moral, ethical, regulatory and scientific principles governing clinical research as set out in the Declaration of Helsinki (1989) and the Good Clinical Practice guideline (GCP). The Center for Clinical Studies of the Department of Surgery Heidelberg is responsible for planning, conducting and final analysis of the trial.  相似文献   

14.
In the field in south-central Sweden, we tested by randomised, standardised methodology the potential anti-tick repellent activity of two concentrations of MyggA Natural spray (containing PMD) (4.2 and 3.2 g/m2) and one of RB86 (with 70% neem oil containing azadirachtin) (3 g/m2) to host seeking nymphs of Ixodes ricinus. Each substance was applied separately to 1 m2 cotton flannel cloths. Nymphal ticks on the cloths, pulled over the vegetation, were recorded at 10-m stops. Nymphal numbers recorded differed significantly between treated cloths [4.2 or 3.2 g MyggA Natural spray/m2 and 3 g RB86/m2] and the untreated control (df = 3, chi2 = 112.74, P < 0.0001). Nymphal numbers also differed significantly among collectors (df = 3, chi2 = 15.80, P < 0.001). Repellency of treated cloths, i.e., 4.2 or 3.2 g MyggA Natural spray/m2 and 3 g RB 86/m2 declined from day 0 (i.e. the day of impregnation) to day 3 after impregnation from 77 to 24%, 58 to 16% and 47 to 0.5%, respectively. This study suggests that all three treatments have significant repellent activities against I. ricinus nymphs.  相似文献   

15.
Adolf’s eelpout, Lycodes adolfi, was found at five bottom trawl stations in 2007–2009, on the slope towards the Sofia Deep north of Spitsbergen, at depths of 970–1,220 m and water temperatures below 0°C. Previously, the species has been known from cold and deep waters south of 74°N to both sides of Greenland and in the Norwegian Sea. The present material represents the first records from the Arctic Ocean and may indicate a wider arctic distribution of this species.  相似文献   

16.
The variety of aquatic nonindigenous animals in marine habitats worldwide includes more than 16 planktonic Copepoda species. Acartia tonsa is a very successful one, distributed in many seas. Its invasion into European seas was analyzed before (Brylinski,1981), but from that time A.tonsa extended its range in European aquatic habitats. The author describes the history of the A.tonsa invasion into the Ponto-Caspian basin as well as some misleading earlier publications. Morphologic differences between A.clausi and A.tonsa, the neglect of which led to the wrong identification, were examined. The data on A.tonsa and total copepod dynamics in the Sevastopol Bay during the period of 1976~1996 and the same data on the Caspian Sea since 1981 were analyzed. The average size of A.tonsa in new habitats decreased, and its relative density in the Black and Caspian Seas gradually increased.  相似文献   

17.
From the mid-1960s onwards, a set of Spanish molecular biology research groups emerged in Spain. The factors contributing to this included: the return of a group of molecular biologists from their postdoctoral period abroad, the negotiations for the return of Spanish-born Nobel prize winner Severo Ochoa from New York, the negotiations for Spanish membership in the European Conference of Molecular Biology, and national policy towards university reform. As a result, the early molecular biologists’ research groups began to be recognised as research schools by Spanish authorities and postgraduate courses and new research centres for molecular biology were set up. Foreign influence in the whole process was crucial.  相似文献   

18.
Various aspects of motherese also known as infant-directed speech (IDS) have been studied for many years. As it is a widespread phenomenon, it is suspected to play some important roles in infant development. Therefore, our purpose was to provide an update of the evidence accumulated by reviewing all of the empirical or experimental studies that have been published since 1966 on IDS driving factors and impacts. Two databases were screened and 144 relevant studies were retained. General linguistic and prosodic characteristics of IDS were found in a variety of languages, and IDS was not restricted to mothers. IDS varied with factors associated with the caregiver (e.g., cultural, psychological and physiological) and the infant (e.g., reactivity and interactive feedback). IDS promoted infants’ affect, attention and language learning. Cognitive aspects of IDS have been widely studied whereas affective ones still need to be developed. However, during interactions, the following two observations were notable: (1) IDS prosody reflects emotional charges and meets infants’ preferences, and (2) mother-infant contingency and synchrony are crucial for IDS production and prolongation. Thus, IDS is part of an interactive loop that may play an important role in infants’ cognitive and social development.  相似文献   

19.
Othenio Abel is widely acclaimed as the founder of paleobiology; of the journal Palaeobiologica and of the Paleobiological Society in Vienna. His National–Socialist sympathies, which he shared with fellow paleobiologist Henry Fairfield Osborn from the American Museum of Natural History, resulted in his forced retirement from the University of Vienna in 1934. Abel secured subsequent employment at the University of Göttingen, later sought help from Nazi officials to create his own institute in Salzburg. A leader amongst German paleontologists, Abel supported efforts of the Deutsche Palaeontologische Gesellschaft to align paleobiology with Nazi ideology (‘National–Socialism is politically applied biology’) to secure more support for the discipline. Abel's paleobiology was neo-Lamarckian in nature, based on a ‘reaction theory’ of adaptation. Abel attempted to unify paleontology with biology under a universal law of nature – the Law of Biological Inertia – that itself was anchored in classical physics.  相似文献   

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