Search results for "NKT"
showing 10 items of 986 documents
Bacterial community response to changes in a tri-trophic cascade during a whole-lake fish manipulation
2015
Microbial communities play a key role in biogeochemical processes by degrading organic material and recycling nutrients, but can also be important food sources for upper trophic levels. Trophic cascades might modify microbial communities either directly via grazing or indirectly by inducing changes in other biotic or in abiotic factors (e.g., nutrients). We studied the effects of a tri-trophic cascade on microbial communities during a whole-lake manipulation in which European perch (Perca fluviatilis) were added to a naturally fishless lake divided experimentally into two basins. We measured environmental parameters (oxygen, temperature, and nutrients) and zooplankton biomass and studied th…
Autotrophic and Heterotrophic Picoplankton in Wetlands: Differences with Lake Patterns
2003
This study describes the occurrence, importance and seasonal patterns of picoplankton in two wetlands (TDNP and La Safor), and compares them to a system of fifteen interconnected lakes (Ruidera). In TDNP we performed a six-year monthly study in three sites of the wetland. Bacterial abundance increased throughout time and the autotrophic picoplankton (APP) range was wide (up to 33 x 10 6 cells/ml). The annual averaged APP contribution to total picoplankton and phytoplankton biovolumes was 0.5-22% and 0.03-6% respectively. There were large differences among sites in terms of APP absolute and relative abundance and seasonal patterns. In La Safor, the APP relative contribution to picoplankton a…
The influence of food competition and host specificity on the transmission of Triaenophorus crassus (Cestoda) and Cystidicola farionis (Nematoda) to …
2000
Abstract As a superior competitor for planktonic food, vendace ( Coregonus albula ), when abundant, is expected to displace whitefish ( Coregonus lavaretus ) from feeding on plankton and to force it to rely more on benthic food. The predicted result would be a reduced abundance of the copepod-transmitted cestode Triaenophorus crassus in whitefish, but an increase in the abundance of the nematode Cystidicola farionis transmitted via benthic amphipods. We studied the occurrence of both parasites in whitefish during 1991–1996 in three interconnected areas at Lake Saimaa, Finland, where the densities of the vendace stocks varied due to natural fluctuation in year-class strengths. In accordance …
Immunoregulatory role of Jα281 T cells in aged mice developing lupus-like nephritis
2007
Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by the emergence of autoreactive T cells. Humans and mice with SLE have reduced numbers of CD1d-restricted invariant natural killer T (iNKT) cells, suggesting a key role for these cells in its immunopathogenesis. This subset uses an invariant TCR constituted by Valpha14 Jalpha281 chains paired with some Vbeta domains. The regulatory role for iNKT cells in non-autoimmune mice was suggested by our previous results showing that aged Jalpha281 knockout (KO) mice produce anti-dsDNA. Here we show that old Jalpha281 KO mice have proteinuria and antibodies against dsDNA and cardiolipin. Histological analysis of Jalpha281 KO m…
Slimību un atkarību ārstēšana ar akupunktūras palīdzību.
2022
Šī pētījuma tēma ir “Slimību un atkarību ārstēšana ar akupunktūras palīdzību”. Pētījuma mērķis ir noskaidrot vai ar akupunktūras palīdzību ir iespējams ārstēt slimības un atkarības. Pētījuma uzdevumi ir analizēt zinātnisko literatūru un citus avotus par akupunktūru, analizēt akupunktūras priekšrocības un efektivitāti slimību un atkarību ārstēšanā, kā arī aptaujāt cilvēkus, kuri ir piedalījušies akupunktūras sesijās, analizēt anketas un izstrādāt secinājumus par darbā iegūtajiem datiem. Pētījumā izmantotās metodes ir zinātniskās literatūras analīze, zinātniskās pētniecības metodes- teorētiskā un empīriskās pētniecības metodes (datu ieguves apstrāde un datu apstrādes materiāli). Pētījumā tika…
Seasonal succession and growth in the plankton communities of the Gulf of Riga in relation to long-term nutrient dynamics
1999
To study temporal changes in phyto- and zooplankton in the Gulf of Riga monitoring data covering the period of 1972–1995 were analyzed. Changes in external nutrient supply have turned P limitation, during the 1980s, into the present deficiency of Si for the spring bloom. Contrary to depletion of the N and Si pools, the internal sources and sinks were responsible for input of P into the pelagic ecosystem in the 1990s. Restructuring of the nutrient pool reshaped the pelagic planktonic communities. Changes of the species composition and food-web relationships occurred. Till the 1990s, an increase of diatoms in the summer phytoplankton and an increase of herbivores in zooplankton took place. La…
Melosira distans var. tenella and Eunotia zasuminensis, two poorly known planktonic diatoms in Finnish lakes
1986
The occurrence and ecology of two poorly known planktonic diatoms, Melosira distans var. tenella (Nyg.) M.-B. Florin and Eunotia zasuminensis (Cabejsz.) Korner in central Finland is discussed. Both species have their maximum in late summer when water temperature is > 15°C and they prefer slightly acid water (pH < 7), low conductivity (less than 4 mS/m) and a moderate degree of dystrophy with C.O.D. 10–20 mg O2/l and water colour 60–120 mg Pt/1. Melosira distans var. tenella was found in ca. 80% of the central Finnish lakes studied, but it is not reported in previously published papers. Eunotia zasuminensis is rarer, but is, however, recorded in at least 22 lakes in central Finland.
Phytoplankton structure in different lake types in central Finland
1986
Phyloplankton structure and its relation to physical and chemical properties of the water was studied in 58 central Finnish lakes. The biomass ranged from 0.2 to 14.2 g m−3 and the number of taxa per sample ranged from 33 to 152. The lakes were grouped into 5 types according to their trophic state: eutrophic, dyseutrophic, mesotrophic, oligotrophic, and acid oligotrophic lakes. The average biomass in eutrophic lakes was 5.57 g m−3, in dyseutrophic 3.54 g m−3, 1.23 g m−3 in mesotrophic, 0.52 g m−3 in oligotrophic and 0.39 g −3 in acid oligotrophic lakes. The average number of taxa per sample in the corresponding lake types were 109. 1, 79.3, 97.9, 90.9 and 43.8, respectively. The phytoplankt…
Thouless-Valatin Rotational Moment of Inertia from the Linear Response Theory
2017
Spontaneous breaking of continuous symmetries of a nuclear many-body system results in appearance of zero-energy restoration modes. Such modes introduce a non-physical contributions to the physical excitations called spurious Nambu-Goldstone modes. Since they represent a special case of collective motion, they are sources of important information about the Thouless-Valatin inertia. The main purpose of this work is to study the Thouless-Valatin rotational moment of inertia as extracted from the Nambu-Goldstone restoration mode that results from the zero-frequency response to the total angular momentum operator. We examine the role and effects of the pairing correlations on the rotational cha…
Mappings of finite distortion : size of the branch set
2018
Abstract We study the branch set of a mapping between subsets of ℝ n {\mathbb{R}^{n}} , i.e., the set where a given mapping is not defining a local homeomorphism. We construct several sharp examples showing that the branch set or its image can have positive measure.