On the spatial distribution of nests of the antsMessor arenariusandMessor ebeninus

Ants of the speciesMessor arenariusandM. ebeninusare known as common granivores in the deserts of the Middle East and North Africa. The relationship between the spatial distribution of nests of these ant species and the distribution of vegetation was examined in the Negev highlands. Using the method of nearest neighbour analysis, it was found that nests ofM. arenariusare evenly dispersed while the dispersion of nests ofM. ebeninusdoes not differ from a random distribution. It is suggested that in desert surroundings there is a connection between the distribution pattern of nests of harvester ants and their foraging type. It seems that nests of individually foraging ants are usually evenly dispersed while nests of trunk-trail foraging ants are usually distributed in a random or aggregated dispersion.     

Three-dimensional VP and VP /VS models of the upper crust in the Friuli area (northeastern Italy)

3-D images of P velocity and P - to S -velocity ratio have been produced for the upper crust of the Friuli area (northeastern Italy) using local earthquake tomography. The data consist of 2565 P and 930 S arrival times of high quality. The best-fitting V _P and V _P / V _S 1-D models were computed before the 3-D inversion. V _P was measured on two rock samples representative of the investigated upper layers of the Friuli crust. The tomographic V _P model was used for modelling the gravity anomalies, by converting the velocity values into densities along three vertical cross-sections. The computed gravity anomalies were optimized with respect to the observed gravity anomalies. The crust investigated is characterized by sharp lateral and deep V _P and V _P / V _S anomalies that are associated with the complex geological structure. High V _P / V _S values are associated with highly fractured zones related to the main faulting pattern. The relocated seismicity is generally associated with sharp variations in the V _P / V _S anomalies. The V _P images show a high-velocity body below 6 km depth in the central part of the Friuli area, marked also by strong V _P / V _S heterogeneities, and this is interpreted as a tectonic wedge. Comparison with the distribution of earthquakes supports the hypothesis that the tectonic wedge controls most of the seismicity and can be considered to be the main seismogenic zone in the Friuli area.     

Stacking for the frequencies and Qs of 0S0 and 1S0

Summary. Using nine IDA records for the Indonesian earthquake of 1977 August 19, we have formed an optimal linear combination of the records and have measured the frequency and Q of ₀ S ₀ and ₁ S ₀. The frequency was measured using the moment ratio method. The attenuation was measured by the minimum width method and by the time-lapse method. The frequency and attenuation were measured simultaneously by varying them to obtain a best fit to the data. A 2000-hr stack, the sum of nine individual records, for ₀ S ₀ gave a frequency of 0.814664 mHz±4 ppm. The values for the Q of ₀ S ₀ for the three different methods of measurement were 5600,5833 and 5700, respectively. The error in the estimates of Q ^-1 is about 5 per cent for the minimum power method. For ₁ S ₀ a 300-hr stack yielded a frequency of 1.63151 mHz±30 ppm. The values of Q for this mode were 1960, 1800 and 1850, respectively, with an error in Q ^-1 of about 12 per cent for the minimum power method.     

Spacing behaviour between two desert rodents, the golden spiny mouseAcomys russatusand the bushy-tailed gerbilSekeetamys calurus

Nest and feeding behaviour patterns were compared between two sympatric species, the bushy-tailed gerbilSekeetamys calurusand the golden spiny mouseAcomys russatus, in order to assess nest site and food as possible resources of competition. The way the species interact under laboratory conditions was also compared. WhileS. calurusused a nest into which they removed bedding material, only two out of sixA. russatusdid so, while in at least half of the studied cases they were found roosting outside of the nest inside the enclosure. When introduced into the same enclosure,S. caluruswas the dominant species and in five out of 12 casesS. calurusinhabited the nest abandoned byA. russatus, and in seven casesA. russatuswas found resting in the enclosure. UnlikeA. russatus,S. calurusaccumulated food inside its nest and also protected the food resource in the enclosure againstA. russatus. It seems that different nest and feeding behavioural patterns can reduce competition between these two sympatric species.     

The effect of disturbance on the day-to-day variability of Sq

Summary. Other workers have recently shown that the apparent day-to-day variability of S_q is appreciably reduced when days with bay-like disturbances are removed from the analysis.
In this paper, it is shown that when these days are removed, there is only a small effect on the scale of the spatial coherence of S_q-ranges and therefore the regional scale of the correlation must be a real feature of S_q range variability rather than an effect due to disturbance.     

NCEP/NCAR 再分析资料在喜马拉雅山-青藏高原气象研究中的可行性分析

Due to the difficult logistics in the extreme high elevation regions over the Himalayas and Tibetan Plateau, the observational meteorological data are very few. In 2003, an automatic weather station was deployed at the northeastern saddle of Mt. Nyainqentanglha (NQ) (30°24′44.3″ N, 90°34′13.1″ E, 5850 m a.s.l.), the southern Tibetan Plateau. In 2005, another station was operated at the East Rongbuk Glacier Col (28°01′0.95″ N, 86°57′48.4″ E, 6523 m a.s.l.) of Mt. Qomolangma. Observational data from the two sites have been compared with the reanalysis data from the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR), reliability of NCEP/NCAR reanalysis data has been investigated in the Himalayas/Tibetan Plateau region. The reanalysis data can capture much of the synoptic-scale variability in temperature and pressure, although the reanalysis values are systematically lower than the observation. Furthermore, most of the variability magnitude is, to some degree, underestimated. In addition, the weather event extracted from the NCEP/NCAR reanalyzed pressure and temperature prominently appears one day ahead of the observational data on Mt. Qomolangma, while on Mt. NQ it occurs basically in the same day.     

Distribution analysis ofAlliumL. species of the Dzhungarian Alatau

In the Dzhungarian Alatau, a large Asian mountain range, 33 species from the polymorphic genusAlliumL. have been found. They belong to the subgeneraRhizirideum,AlliumandMelanocrommyumand are distributed from the foothills to alpine belts. The geographical and genesis analysis of these species is given. Five species can be ascribed to the category of autochtonous of the region, among them one being endemic to the Dzhungarian Alatau.