ErdH{o}s [On Sch"utte problem, Math. Gaz. 47 (1963)] proved that every tournament on $n$ vertices has a directed dominating set of at most $log (n+1)$ vertices, where $log$ is the logarithm to base $2$. He also showed that there is a tournament on $n$ vertices with no directed domination set of cardinality less than $log n - 2 log log n + 1$. This notion of directed domination number has been g...

In this study a parasitological investigation on 238 samples of Neogobius species from the south-east of Caspian Sea was carried out. The samples including Neogobius melanostomus (35), N. fluviatilis pallasi (103), N. kessleri gorlap (70) and N. bathybius (30) were seasonally seined by beach net during one year (summer 2006-spring 2007), fixed in 10 % buffer formalinand transferred to the labor...

Separation of some biogenic amines via RP-HPLC using mixed micellar mobile phase was investigated. The compounds were derivatized before hand by dansyl chloride as a chromophoric reagent. Appropriate conditions for separation, were determined by studying factors such as temperature, type and percentage of organic modifier, concentration of surfactants (SDS and Brij-35) and the pH of the mob...

the leaf nitrogen content is generally accepted as an indicator of food quality and as a factor affecting host selection by phytophagous insects. the alate pea aphids (acyrthosiphon pisum harris, aphididae) were given a choice among non-nodulated pea plants (pisum sativum l.) supplied with one of four nitrate-n levels (0, 3, 15 and 30 mm). when whole plants were exposed to aphids for 7 days, th...

separation of some biogenic amines via rp-hplc using mixed micellar mobile phase was investigated. the compounds were derivatized before hand by dansyl chloride as a chromophoric reagent. appropriate conditions for separation, were determined by studying factors such as temperature, type and percentage of organic modifier, concentration of surfactants (sds and brij-35) and the ph of the mobile ...

Gazestan magnetite-apatite deposit is located in Central Iran and Bafq region, which has been occurred in form of veins, veinlets, and small apatite lenses as well as magnetite in metasomatic rock types such as green chlorite-actinolite rock units. These rocks are situated in the carbonate-volcanic complex of Upper Precambrian-Lower Cambrian Rizo formation. In this study, staged factor analysis...