Galaxy groups at 0.3 ≤z≤ 0.55 – I. Group properties     

D. J. Wilman †  M. L. Balogh ‡  R. G. Bower  J. S. Mulchaey  A. Oemler  Jr    R. G. Carlberg  S. L. Morris  R. J. Whitaker 《Monthly notices of the Royal Astronomical Society》2005,358(1):71-87

The evolution of galaxies in groups may have important implications for the evolution of the star formation history of the Universe, since many processes which operate in groups may suppress star formation and the fraction of galaxies in bound groups grows rapidly between   z = 1  and the present day. In this paper, we present an investigation of the properties of galaxies in galaxy groups at intermediate redshift  ( z ∼ 0.4)  . The groups were selected from the Canadian Network for Observational Cosmology Redshift Survey (CNOC2) redshift survey as described by Carlberg et al., with further spectroscopic follow-up undertaken at the Magellan telescope in order to improve the completeness and depth of the sample. We present the data for the individual groups, and find no clear trend in the fraction of passive galaxies with group velocity dispersion and group concentration. We stack the galaxy groups in order to compare the properties of group galaxies with those of field galaxies at the same redshift. The groups contain a larger fraction of passive galaxies than the field, this trend being particularly clear for galaxies brighter than   M _{B J} < −20  in the higher velocity dispersion groups. In addition, we see evidence for an excess of bright passive galaxies in the groups relative to the field. In contrast, the luminosity functions of the star-forming galaxies in the groups and the field are consistent. These trends are qualitatively consistent with the differences between group and field galaxies seen in the local Universe.  相似文献   

Uptake and discharge of petroleum hydrocarbons by barnacles     

R.J. Morris 《Marine pollution bulletin》1973,4(7):107-109

The hydrocarbon content of barnacles living on tarballs has been compared with the hydrocarbon composition of the tarballs. While there is some contamination of the barnacles there is no evidence of gross pollution and the analyses suggest that oil hydrocarbons are assimilated and then discharged, unmetabolized, quite rapidly.  相似文献   

The origins of the magnetic anomaly over the Lough Derg Complex, Co. Donegal, Ireland     

P. Morris 《Geophysical Journal International》1982,71(3):693-701

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A short note on early Cambrian palaeomagnetism from Normandy, France     

Rob Van der Voo  W. A. Morris 《Geophysical Journal International》1982,68(1):269-271

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Conodont palaeobiology: recent progress and unsolved problems     

S. Conway Morris 《地学学报》1989,1(2):135-150

The fossilized soft-parts of conodonts are extraordinarily rare; excluding dubious and refuted examples, only 10 specimens are known. Nine come from the Lower Carboniferous of Granton, Scotland, and represent at least two genera with complex polygnathacean apparatuses. The soft-parts include well-defined myotomal segmentation and a probable notochord, thus strongly suggesting affinity with the chordates. The tenth specimen, from the Lower Silurian of Waukesha, Wisconsin, bears a simpler apparatus of panderodontid conodont elements. The soft-parts are very poorly preserved, but appear to be unlike those of the Granton specimens. In both occurrences the conodont apparatus appears well adapted for grasping and biting, supporting earlier suggestions that conodont elements acted as teeth. Many conodonts were probably predators or scavengers, but other feeding modes are not necessarily excluded. Other aspects of conodont palaeobiology reviewed here include mode of life and possible migration, reproduction and genetics, and palaeopathology. All these topics rely almost exclusively on the study of conodont elements, and many problems of conodont palaeobiology await further research.  相似文献   

A palaeomagnetic study of Cambrian red beds from Cartaret, Normandy, France     

W. A. Morris 《Geophysical Journal International》1980,62(3):577-590

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Nutrient distributions in an estuary: Evidence of chemical precipitation of dissolved silicate and phosphate     

A.W. Morris  A.J. Bale  R.J.M. Howland 《Estuarine, Coastal and Shelf Science》1981,12(2):205-216

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The Magnetization of a Baked Limestone Contact in the County Mayo, Ireland     

P. Morris 《Geophysical Journal International》1972,29(4):487-492

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A.J.J. van Woerkom (1915–1991)     

Raynor L. Duncombe  Morris S. Davis 《Celestial Mechanics and Dynamical Astronomy》1992,53(1):vi-1

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The ability of a field population of diatoms to discriminate between phosphate and arsenate     

R.J. Morris  M.J. McCartney  A.G. Howard  M.H. Arbab-Zavar  J.S. Davis 《Marine Chemistry》1984,14(3):259-265

Dissolved inorganic arsenic and phosphate levels present in an enclosed experimental ecosystem have been studied during the course of a natural spring diatom bloom. Whilst phosphate levels dropped rapidly to almost zero as the bloom developed, arsenic levels remained constant even when arsenate levels exceeded the dissolved phosphate. Certain diatom species (Thalassiosira spp., Chaetoceras spp. and Skeletonema costatum) therefore appear to be capable of discriminating, either by uptake or excretion, between phosphate and arsenate. The implications of such findings are discussed.  相似文献