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  • 1
    Call number: MOP Mf 1621
    Type of Medium: Monograph available for loan
    Pages: 27 Mf
    Location: MOP - must be ordered
    Branch Library: GFZ Library
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  • 2
    ISSN: 1432-0762
    Keywords: Key words Attini ; CAP-PCR DNA fingerprinting ; Polyandry ; Polyethism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The mating frequency of queens was estimated for eight attine ant species, Myrmicocrypta ednaella, Apterostigma mayri, Cyphomyrmex costatus, C. rimosus (four lower attines), Trachymyrmex isthmicus, Serico-myrmex amabalis, Acromyrmex octospinosus and Atta colombica (four higher attines), and correlated to colony size, worker polyethism, and sex ratio. Mating frequency was calculated from within-colony relatedness estimated by CAP-PCR DNA fingerprinting. Most queens of lower attines and T. isthmicus mated with only one male, while those of the three higher attines mated with multiple males. Mating frequency was positively correlated with colony size. Polyethism among workers was dependent on worker age in lower attines but on body size in higher attines, suggesting some correlation between mating frequency (i.e., within-colony gene diversity) and caste complexity. The sex ratio was biased toward females in species where the mating frequency equaled one, but toward males in species where the mating frequency was greater than two. Changing in nest site from ground surface to deep underground may have facilitated the evolution of large colony size in Attini, and this may have resulted in the evolution of polyandry (a queen mates with multiple males). With the evolution of polyandry in higher attines, Atta and Acromyrmex in particular have generated high genetic diversity within their colonies and complex social structures.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1662-9779
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Physics
    Notes: Surface hardening treatment of titanium materials in use of CO gas was studied includinginvestigation of post heat treatment under vacuum. C.P. titanium, α+β type SP-700 alloy withTi-4.5%Al-3%V-2%Mo-2%Fe and β type alloy with Ti-15%Mo-5%Zr-3%Al were used. Surface hardeningwas conducted by heating these materials at 1073K for 21.6ks in Ar-5%CO gas. Subsequently, specimenssubjected to surface hardening were heated at 1073k for various time periods under vacuum. While themaximum surface hardness value was the largest in C.P. titanium and the least in SP-700 alloy, hardeninglayer thickness was the thickest in β type alloy and the thinnest in C.P. titanium. Surface hardening in C.P.titanium was brought about by solid solution hardening due to oxygen and carbon. Enrichment of theseelements in the surface layer of both titanium alloys caused continuous variations of the microstructure suchas β to α+β, or their volume fractions in the surface hardening layer. Post heat treatment at 1073K increasedthe maximum surface hardness and hardening layer thickness with an extension of the heating time in C.P.titanium, but the surface maximum hardness decreased continuously in β type titanium alloy. Post heattreatment could remove the thin oxide layer formed by surface hardening treatment
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The effects of elemental powder characteristics, binder content and its composition, as well as some additives on pressure change and drainage phenomenon of pastes during extrusion have been mainly investigated. The pastes consisted of a powder, zirconia or stainless steel, and a water-based binder, an aqueous solution of water-soluble polymer (hydroxypropyl methylcellulose). The drainage phenomenon has been found in extrusion of the stainless steel pastes with lower binder contents, while the zirconia pastes show a small probability of drainage in the range of the binder contents used in this investigation. It is shown that broadening particle size distribution by mixing powders with different average particle sizes has a significant effect on decreasing extrusion pressure and restraining occurrence of the drainage phenomenon, thus improving the extrudability of pastes. It is effective to increase the binder content in pastes, raise the mixing fraction of HPMC in binder and add plasticizer like glycerol, in order to reduce occurrence of the drainage phenomenon during extrusion of the stainless steel pastes.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Various kinds of SnO2 films, modified with the addition of iron, antimony, copper, titanium, manganese, nickel, cobalt or calcium oxides, were fabricated by using the spray pyrolysis technique and their gas-sensing characteristics were studied. From electrical measurements in air, the relative sensitivity towards inflammable gas of these SnO2-based film sensors was compared. It was observed that SnO2-based films of higher electrical resistance had a tendency to have higher sensitivity towards ethanol than the SnO2-based films of lower resistance. The addition of p-type metal oxides, such as NiO and MnO, to the SnO2 matrix was found to be effective in increasing the sensitivity towards inflammable gas.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Corrosion behaviour of Si3N4 ceramics containing Y2O3, Al2O3 and AIN as sintering aids was investigated under hydrothermal conditions at 200–300
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Two powders with different average particle sizes and size distributions were blended in various proportions. The influence of powder mixing on extrusion behavior of pastes containing a water-based binder has been examined. The bimodal mixed stainless steel powder exhibits a low extrusion pressure, small amount of binder and high green density when the mixing fractions of large and small particles are approximately equal. With regard to the mixing of zirconia and stainless steel powders, a similar result has been found, but the mixing fraction of powder corresponding to the optimal packing is shifted to stainless steel-side. In order to improve the extrudability of pastes, it is effective to mix two powders with a large difference in particle size.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1573-4811
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Meteorology and atmospheric physics 44 (1990), S. 85-100 
    ISSN: 1436-5065
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography , Physics
    Notes: Summary Interannual modes are described in terms of three-month running mean anomaly winds (u″,v″), outgoing longwave radiation (OLR″), and sea surface temperature (T * ″ ). Normal atmospheric monsoon circulations are defined by long-term average winds (u n,v n) computed every month from January to December. Daily winds are grouped into three frequency bands, i.e., 30–60 day filtered winds (u L,v L); 7–20 day filtered winds (u M,v M); and 2–6 day filtered winds (u S,v S). Three-month running mean anomaly kinetic energy (signified asK L ″ , K M ″ , andK S ″ , respectively) is then introduced as a measure of interannual variation of equatorial disturbance activity. Interestingly, all of theseK L ″ , K M ″ , andK S ″ perturbations propagate slowly eastward with same phase speed (0.3 ms−1) as ENSO modes. Associated with this eastward propagation is a positive (negative) correlation between interannual disturbance activity (K L ″ , K M ″ , K S ″ ) and interannualu″ (OLR″) modes. Namely, (K L ″ , K M ″ , K S ″ ) becomes more pronounced than usual nearly simultaneously with the arrival of westerlyu″ and negativeOLR″ (above normal convection) perturbutions. In these disturbed areas with (K L ″ , K M ″ , K S ″ 〉0), upper ocean mixing tends to increase, resulting in decreased sea surface temperature, i.e.T * ″ ≦0. Thus, groups (not individual) of equatorial disturbances appear to play an important role in determiningT * ″ variations on interannual time scales. HighestT * ″ occurs about 3 months prior to the lowestOLR″ (convection) due primarily to radiational effects. This favors the eastward propagation of ENSO modes. The interannualT * ″ variations are also controlled by the prevailing monsoonal zonal windsu n, as well as the zonal advection of sea surface temperature on interannual time scales. Over the central Pacific, all of the above mentioned physical processes contribute to the intensification of eastward propagating ENSO modes. Over the Indian Ocean, on the other hand, some of the physical processes become insignificant, or even compensated for by other processes. This results in less pronounced ENSO modes over the Indian Ocean.
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  • 10
    ISSN: 1434-601X
    Keywords: PACS:21.10.Tg Lifetimes – 23.20.Js Multipole matrix elements – 27.60.+j 90 ≤ A ≤ 149
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: The lifetime of the ((11/2)−) state at 267keV in 125Cs was measured. A Ge detector with the transistor reset preamplifier(TRP Ge) was used to measure delayed γ-rays under an intense prompt background. The B(M2) value deduced from the lifetime was found to be consistent with the Weisskopf estimate.
    Type of Medium: Electronic Resource
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