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1.
Background
Chow and Liu showed that the maximum likelihood tree for multivariate discrete distributions may be found using a maximum weight spanning tree algorithm, for example Kruskal's algorithm. The efficiency of the algorithm makes it tractable for high-dimensional problems. 相似文献2.
S?ren Franzenburg Sebastian Fraune Philipp M Altrock Sven Künzel John F Baines Arne Traulsen Thomas CG Bosch 《The ISME journal》2013,7(4):781-790
Animals are colonized by complex bacterial communities. The processes controlling community membership and influencing the establishment of the microbial ecosystem during development are poorly understood. Here we aimed to explore the assembly of bacterial communities in Hydra with the broader goal of elucidating the general rules that determine the temporal progression of bacterial colonization of animal epithelia. We profiled the microbial communities in polyps at various time points after hatching in four replicates. The composition and temporal patterns of the bacterial communities were strikingly similar in all replicates. Distinct features included high diversity of community profiles in the first week, a remarkable but transient adult-like profile 2 weeks after hatching, followed by progressive emergence of a stable adult-like pattern characterized by low species diversity and the preponderance of the Betaproteobacterium Curvibacter. Intriguingly, this process displayed important parallels to the assembly of human fecal communities after birth. In addition, a mathematical modeling approach was used to uncover the organizational principles of this colonization process, suggesting that both, local environmental or host-derived factor(s) modulating the colonization rate, as well as frequency-dependent interactions of individual bacterial community members are important aspects in the emergence of a stable bacterial community at the end of development. 相似文献
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PR Marcelino MS Aoki AFS Arruda CG Freitas A Mendez-Villanueva A Moreira 《Biology of sport / Institute of Sport》2016,33(1):37-42
The purpose of this study was to investigate the effect of court size on physiological responses and physical performance of young elite basketball players. Twelve male basketball players (18.6 ± 0.5 years; 88.8 ± 14.5 kg; 192.6 ± 6.5 cm) from an under-19 team performed two small-sided games (matches) with different court areas (28x15 m and 28x9 m; 28x15 and 28x9 protocols). The number of players (3x3) was kept the same in each protocol. The players performed a repeated-sprint ability (RSA) test before and after each match. Blood lactate concentration was collected before (pre) and after (post) the matches, and the session rating of perceived exertion (session-RPE) was determined 30 minutes after the match. Best and mean time in the RSA test were not different between the 28x15 and the 28x9 match protocols (p > 0.05). A significant difference was observed for lactate concentration from pre- to post-match (p < 0.05) in both protocols (28x15 and 28x9); however, there was no significant interaction between protocols. A similar session-RPE mean score (28x15: 7.2 ± 1.4 and 28x9: 6.6 ± 1.4) was detected for both protocols (p > 0.05, ES=0.41). In summary, the results of the current study suggest that the different court areas induced similar responses. Although there was no significant difference in effort perception, players tended to perceive a greater effort in the larger court size. 相似文献
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Fiamegos YC Nanos CG Stalikas CD 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2004,813(1-2):89-94
A derivatization-extraction method that avoids tedious preconcentration steps is established in order to determine amino acids accurately at nanogram levels. The method involves conversion of the analytes of concern to N(O,S)-ethoxycarbonyl amino acid ethyl esters and subsequent extraction by single-drop microextraction (SDME) followed by GC analysis. The reaction proceeds smoothly and rapidly under ultrasonication which removes the bubbles from the bulk solution. Precision is acceptable and 12 non-hydrolyzed amino acids can be determined in urine in this manner. As long as the extraction conditions are consistently applied, quantitative analysis can be performed accurately. The limits of detection were satisfactory in the range 0.010-0.025 microg/ml for GC-FID and 0.26-68 ng/ml for GC-MS(SIM) with 1 ml sample volume. 相似文献
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D Taruscio C Morciano P Laricchiuta P Mincarone F Palazzo CG Leo S Sabina R Guarino J Auld T Sejersen D Gavhed K Ritchie M Hilton-Boon J Manson PG Kanavos D Tordrup V Tzouma Y Le Cam J Senecat G Filippini S Minozzi C Del Giovane H Schünemann JJ Meerpohl B Prediger L Schell R Stefanov G Iskrov T Miteva-Katrandzhieva P Serrano-Aguilar L Perestelo-Perez MM Trujillo-Martín J Pérez-Ramos A Rivero-Santana A Brand H van Kranen K Bushby A Atalaia J Ramet L Siderius M Posada I Abaitua-Borda V Alonso Ferreira M Hens-Pérez FJ Manzanares 《Orphanet journal of rare diseases》2014,9(Z1):O14
7.
Background
The ability to regulate transgene expression has many applications, mostly concerning the analysis of gene function. Desirable induction characteristics, such as low un-induced expression, high induced expression and limited cellular heterogeneity, can be seriously impaired by chromosomal position effects at the site of transgene integration. Many clones may therefore need to be screened before one with optimal induction characteristics is identified. Furthermore, such screens must be repeated for each new transgene investigated, and comparisons between clones with different transgenes is complicated by their different integration sites. 相似文献8.
We studied, under laboratory conditions, the performance of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), immature stages in intact whole fruit of three sweet orange varieties, lemon, and bitter oranges. Both citrus variety and fruit part (flavedo, albedo, and pulp) had strong effects on larval performance, smaller effects on pupae, and no effects on eggs. Fruit peel was the most critical parameter for larval development and survival, drastically affecting larval survival (inducing very high mortality rates). Among fruit regions, survival of larvae placed in flavedo was zero for all varieties tested except for bitter orange (22.5% survival), whereas survival in albedo was very low (9.8-17.4%) for all varieties except for bitter orange (76%). Survival of pupae obtained from larvae placed in the above-mentioned fruit regions was high for all varieties tested (81.1-90.7%). Fruit pulp of all citrus fruit tested was favorable for larval development. The highest survival was observed on bitter oranges, but the shortest developmental times and heaviest pupae were obtained from orange cultivars. Pulp chemical properties, such as soluble solid contents, acidity, and pH had rather small effects on larval and pupal survival and developmental time (except for juice pH on larvae developmental duration), but they had significant effects on pupal weight. 相似文献
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Abstract Helicoverpa armigera oviposition preference for, and larval development on sorghum hybrids with differing resistance to sorghum midge, Stenodiplosis sorghicola , were investigated. When H. armigera larvae were fed seed of resistant and susceptible hybrids in the laboratory there were no differences in larval and pupal sizes or the rate of development. The same result was recorded when larvae fed on panicles on plants in a glasshouse. On some sampling occasions, significantly more eggs were laid on panicles of resistant hybrids in the field. This occurred when plants were in plots and also in a mixed planting. Midge-resistance status did not affect levels of egg parasitism. In a field study using recombinant inbred lines between a midge-resistant and a midge-susceptible line, no relationship was found between level of resistance and oviposition of H. armigera . We conclude that, although midge-resistant hybrids are sometimes preferred for oviposition by H. armigera, the resistance per se does not determine this preference. Egg survival, larval survival, development and resultant damage are not significantly affected by the midge-resistance status of the host. 相似文献
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