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  • 1
    ISSN: 1420-9098
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Summary A study of the ant population in a sector of the Sierra Morena (South Spain) has been made. The objective of this work is to study the influence that a biotic factor (vegetation) and an abiotic one (exposure) may have on the distribution of these species. In order to carry out these experiments a stratified sampling in the main existing combinations between the vegetation units and their exposure was made. The analysis of the correspondances has made it possible to distinguish the indicative species of the main kinds of vegetation of the studied area (pasture, pine plantation and zone exposed to flooding). Through the analysis of the data, when the samples of the zone exposed to flooding are excluded, it is possible to distinguish the indicative species of areas where the bushwood or the pasture are dominant, as well as the ones indicative of areas with different exposure. It is not possible to distinguish indicative species of the previously established sectors in the repopulated zone. This could be interpreted as a consequence of the homogeneization due to human management.
    Abstract: Resumen Se ha realizado un estudio de las poblaciones de hormigas de un sector de Sierra Morena central (Sur de España). El trabajo tiene como objetivo estudiar la influencia que un factor de tipo abiótico (exposición) y otro biótico (vegetacion) tienen sobre la distribución de estas especies. Para ello se ha realizado un muestreo estratificado en las principales combinaciones existentes entre las unidades de vegetación presentes en la zona de estutio y su exposición. El análisis de correspondencias ha permitido, en primer lugar, separar las especies indicadoras de los principales tipos de vegetación de la zona (pastizal, repoblación de pinos y zona inundable del río). En el análisis efectuado, cuando se suprimen los inventarios de la zona inundable, se pueden distinguir las especies indicadoras de zonas donde predomina el matorral, ó el pasto herbáceo, así como las que son indicadoras de zonas con exposición a solana ó umbría. Dentro de la zona repoblada no es posible distinguir especies indicadoras de los sectores previamente establecidos, lo que puede interpretarse como una consecuencia de la homogeneización debida al manejo humano.
    Notes: Resume Le but de ce travail est d'étudier l'influence d'un facteur biotique (la végétation) et d'un facteur abiotique (l'exposition) sur la distribution des espèces de fourmis dans une zone de la Sierra Morena Centrale (Sud de l'Espagne). Pour cela, on a réalisé des échantillonnages stratifiés dans chaque unité de végétation, en soulane et en ombrée. L'analyse des correspondances a permis d'abord de séparer les espèces trouvées dans les principaux types de végétation de la zone d'étude (pâturage, reboisement de pins et zone inondée le long d'une rivière). Quand on supprime les relevés des endroits inondables, on peut distinguer les espèces indicatrices des zone où prédominent soit le maquis («matorral») soit le pâturage («dehesa»), ainis que celles des zones exposées en soulane ou en ombrée. Dans la zone reboisée, il est impossible de distinguer des espèces indicatrices des associations végétales caractéristiques du milieu, ce qui peut s'interpréter comme une conséquence de l'homogénéisation due aux pratiques culturales.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Insectes sociaux 46 (1999), S. 119-125 
    ISSN: 1420-9098
    Keywords: Key words: Granivorous ants, foraging, cooperation, seed mass, Messor barbarus.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary: A mechanism for co-operative load transport was detected in the seed-harvesting ant Messor barbarus. Workers co-operated sequentially, transferring the load from one to another and thus forming what might be termed a transport chain. Although most of the colony's workers could have transported loads unaided, co-operation was prompted by the appearance of high loading ratios in the vicinity of the food source. The first worker in such a chain tended to be small or medium-sized, with a high loading ratio, while the last was larger, and had a correspondingly lower loading ratio. This strategy was of major benefit to the colony, in that it considerably reduced the time required for transport to the nest.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0649
    Keywords: 78 ; 42.65 ; 61.40 ; 73 ; 73.20 ; 82 ; 81.15
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 90 (1989), S. 6701-6708 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The rotational, angular, and translational scattering behavior of NO molecules prepared in a single ro-vibrational state before their interaction with a cleaved graphite surface was determined (v=1→v=1 process). Moreover, the deactivation probability of the vibrational energy into the rotational and translational motion of the molecule could be evaluated (v=1→v=0 process). Finally, it was possible to investigate the scattering behavior of NO molecules that experienced vibrational excitation during their surface encounter (v=0→v=1 process).
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 4368-4376 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We report on the scattering of supersonic NO molecules from a diamond (111) surface. Using state selective laser techniques combined with mass selective quadrupole measurements, we observe two novel features in the molecule–surface interaction: first, a scattering behavior which is dependent on the direction of the incoming molecules; and second, surface residence times that are unusually long, but temperature independent. The former observation can be traced back to the topography of the unreconstructed diamond (111) surface, the latter one can be understood when a temporary function of a metastable surface–molecule complex is assumed.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 82 (1985), S. 4388-4389 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Laser-induced infrared fluorescence was used to measure the collision-induced vibrational energy relaxation in dichloromethane (CH2Cl2). The activation and deactivation of the υ8 and υ3/υ9 vibrational modes was measured after excitation of CH-stretching vibrations near 3000 cm−1. Rate constants for the energy transfer are deduced leading to a simplified model for the vibrational relaxation in CH2Cl2.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 97 (1992), S. 6880-6889 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The translational, rotational, and vibrational dependencies of NO molecules scattered from a diamond (110) surface have been investigated for a series of scattering geometries. The integral and state selected angular distributions of the scattered molecules have been measured. In the exit channel the velocities of molecules in selected states as well as the rotational population distributions in the two lowest vibrational states (ν=0,1) were analyzed for a variety of incoming energies (200 cm−1≤Ekin≤2600 cm−1), scattering angles, and surface temperatures. Molecules with a fast incoming velocity and a rotational energy of Erot≤1000 cm−1 after scattering (about 75% of all molecules) exhibit an elastic interaction with the surface (no energy exchange with the surface, Ekin+Erot=const). For molecules receiving higher rotational energy during the scattering process (Erot≥1000 cm−1) an increasing influence of the surface temperature on their final rotational and translational motion was found. For slow incoming molecules such a dependence is also observed but less pronounced. About 5×10−3 of the incoming molecules are vibrationally excited during their encounter with the surface, and exhibit, after the scattering, angular, and rotational population distributions which are similar to those of the molecules which remain in the vibrational ground state during the scattering process. Rotation of the (110) surface around its normal by 90° leads to identical scattering results: there is no detectable influence of the various surface topographies on the molecular scattering behavior within our present experimental accuracy.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 3020-3021 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A pulsed supersonic nozzle is presented which can be heated to 1300 K and cooled to 4 K. The whole system is composed of quartz to prevent the decomposition of the molecules at a high temperature. The nozzle has produced gas pulses at a rate of 10 Hz and pulse lengths of 5 ms. The performance of the system is demonstrated by the flight time and the rotational temperature of NO molecules as a function of the stagnation pressure and the nozzle temperature.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 407-411 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The construction and operation of a novel high temperature pulsed quartz nozzle employed for the generation of rotationally excited supersonic molecular beams are reported herein. At high stagnation pressures ((approximately-greater-than) 1 bar) the NO molecules in the beam pulse exhibit a translational and rotational behavior identical to heated continuous nozzles (Trot〈50 K; Ekin≈7/2 kTN). At reduced stagnation pressures (10 mbar–1 bar) the rotational temperatures of the beam molecules are increased substantially (up to Trot≈700 K) accompanied by a translational behavior, which can be characterized by a small Mach number. The design has produced the rotationally hottest supersonic beam ever prepared in the pulsed mode.
    Type of Medium: Electronic Resource
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  • 10
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    Unknown
    Boston, Mass. : Periodicals Archive Online (PAO)
    Studies in Romanticism. 13:4 (1974:Fall) 333 
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