4,430 research outputs found
New and Revised Llandovery (Early Silurian) Rugose Corals from Central Western New South Wales
Revision of some of the early Silurian rugose coral faunas from central western New South Wales and study of additional new collections warrants the introduction of a number of new taxa and some previous generic assignments need to be updated. The new cystiphyllinid genus Gephyrelasma McLean is proposed, comprising type species Dentilasma ramosum McLean and G. stevensi McLean sp. nov. The new kodonophyllid genus Vitiliphyllum McLean, with type species V. jenkinsi McLean sp. nov., and the new arachnophyllid genus Latomiphyllum McLean, with type species Arachnophyllum ? epistomoides Etheridge, are introduced. Additional new species include the tryplasmatids Aphyllum ulahense McLean and A. picketti McLean, as well as the ptychophyllinid Ptychophyllum sutorense McLean. Grewingkia neumani McLean is now regarded as a probable representative of the kodonophyllid Cyatholasma Ivanovskiy, while Dentilasma honorabile Ivanovskiy sensu McLean is now only tentatively assigned to that species. Since the original studies of the coral faunas, there has been considerable revision of the lithostratigraphy and biostratigraphy of the relevant sequences. The most current interpretations are reviewed and summarized here
Phylum arthropoda, subphylum trilobitomorpha: trilobites
This volume is the second of three that provide a complete review and inventory of New Zealand\u27s entire living and fossil biodiversity - an international effort involving more than 220 New Zealand and overseas specialists and the most comprehensive of its kind in the world. Together, the three volumes will list every one of the almost 55,000 known species of New Zealand\u27s animals, plants, fungi and micro-organisms. Volume 2 mostly deals with the major branch of the animal kingdom known as Ecdysozoa (moulting animals), which includes arachnids, centipedes and millipedes, crustaceans and insects. It also includes the enigmatic phylum Chaetognatha (arrow worms) and concludes with a chapter on the fossil traces - ichnofossils - of ancient animal activities. All three volumes are affiliated with Species 2000, an international scientific project with the long-term goal of enumerating all known species on Earth into one seamless list - the Catalogue of Life, a kind of online biological telephone directory.To date, only New Zealand has compiled a checklist of its entire biota. Approximately 52% of this country\u27s species are endemic - found only in New Zealand\u27s freshwater, marine, and land environments. We have a responsibility to the global community to preserve this unique heritage or taonga. But further than that, all of our species - including many of the naturalised aliens included in the survey - are important to New Zealand\u27s economy, ecology and well-being. Written for the advanced high-school and tertiary-level reader, these volumes are intended to be a kind of \u27Cooks Tour\u27 of the kingdoms and phyla of life that will, it is hoped, provide an appreciation of the wondrous diversity of nature
Student conceptions about energy transformations: progression from general chemistry to biochemistry
Students commencing studies in biochemistry must transfer and build on concepts they learned in chemistry and biology classes. It is well established, however, that students have difficulties in transferring critical concepts from general chemistry courses; one key concept is âenergy.â Most previous work on studentsâ conception of energy has focused on their understanding of energy in the context of physics (including the idea of âworkâ) and/or their understanding of energy in classical physical and inorganic chemistry contexts (particularly Gibbs Free Energy changes, the second law of thermodynamics, and equilibrium under standard conditions within a closed system). For biochemistry, students must go beyond those basic thermodynamics concepts of work, standard energy changes, and closed systems, and instead they must consider what energy flow, use, and transformation mean in living, open, and dynamic systems. In this study we explored studentsâ concepts about free energy and flow in biological chemical reactions and metabolic pathways by surveys and in-depth interviews. We worked with students in general chemistry classes and biochemistry courses in both an Australian and a US tertiary institution. We address three primary questions (i) What are the most common alternative conceptions held by students when they explain energy-related phenomena in biochemistry?, (ii) What information do students transfer from introductory chemistry and biology when they are asked to consider energy in a biological reaction or reaction pathway?, and (iii) How do students at varying levels of competence articulate their understandings of energy in pathways and biological reactions? The answers to these questions are used to build a preliminary learning progression for understanding âenergyâ in biochemistry. We also propose crucial elements of content knowledge that instructors could apply to help students better grasp this threshold concept in biochemistry
A giant new trimerellide brachiopod from the Wenlock (Early Silurian) of New South Wales, Australia
Keteiodoros bellense n.gen. and n.sp. is a remarkably large trimerellide brachiopod from the Wenlock Dripstone Formation, southeast of Wellington, central New South Wales. The probable articulatory mechanism is unusual for trimerellides. It apparently involved both flattened sections of the lateral commissures which acted as pivots for opening and closing the shell, and a large and strongly modified articulating plate (which partly envelopes a robust dorsal umbo) articulating with the pseudointerarea at the posterior end of the ventral platform. The heavy dorsal umbo probably acted as a counterbalance to the anterior part of the valve; the diductor muscles were apparently attached to the umbo at the sides of the articulating plate, and to the anterior end of the ventral platform. The trimerellides occur in presumed life position in nearly mono specific beds which are interpreted as having formed in a quiet inshore shallow subtidal area on a sloping shelf, protected by coral biostromes but periodically disrupted by storm action. They are considered to represent a low-diversity quietwater Benthic Assemblage 2 community
Simultaneous Observations of Comet C/2002 T7 (LINEAR) with the Berkeley-Illinois-Maryland Association and Owens Valley Radio Observatory Interferometers: HCN and CH_3OH
We present observations of HCN J = 1-0 and CH_3OH J(K_a, K_c) = 3(1, 3)-4(0, 4) A+ emission from comet C/2002 T7 (LINEAR) obtained simultaneously with the Owens Valley Radio Observatory (OVRO) and Berkeley-Illinois-Maryland Association (BIMA) millimeter interferometers. We combined the data from both arrays to increase the (u, v) sampling and signal to noise of the detected line emission. We also report the detection of CH_3OH J(K_a, K_c) = 8(0, 8)-7(1, 7) A^+ with OVRO data alone. Using a molecular excitation code that includes the effects of collisions with water and electrons, as well as pumping by the Solar infrared photons (for HCN alone), we find a production rate of HCN of 2.9 Ă 10^(26) s^(â1) and for CH_3OH of 2.2 Ă 10^(27) s^(â1). Compared to the adopted water production rate of 3 Ă 10^(29) s^(â1), this corresponds to an HCN/H_2O ratio of 0.1% and a CH_3OH/H_2O ratio of 0.7%. We critically assess the uncertainty of these values due to the noise (~10%), the uncertainties in the adopted comet model (~50%), and the uncertainties in the adopted collisional excitation rates (up to a factor of 2). Pumping by Solar infrared photons is found to be a minor effect for HCN, because our 15" synthesized beam is dominated by the region in the coma where collisions dominate. Since the uncertainties in the derived production rates are at least as large as one-third of the differences found between comets, we conclude that reliable collision rates and an accurate comet model are essential. Because the collisionally dominated region critically depends on the water production rate, using the same approximate method for different comets may introduce biases in the derived production rates. Multiline observations that directly constrain the molecular excitation provide much more reliable production rates
Ex-vivo HRMAS of adult brain tumours: metabolite quantification and assignment of tumour biomarkers
Background: High-resolution magic angle spinning (HRMAS) NMR spectroscopy allows detailed metabolic analysis
of whole biopsy samples for investigating tumour biology and tumour classification. Accurate biochemical
assignment of small molecule metabolites that are âNMR visibleâ will improve our interpretation of HRMAS data
and the translation of NMR tumour biomarkers to in-vivo studies.
Results: 1D and 2D 1H HRMAS NMR was used to determine that 29 small molecule metabolites, along with 8 macromolecule signals, account for the majority of the HRMAS spectrum of the main types of brain tumour(astrocytoma grade II, grade III gliomas, glioblastomas, metastases, meningiomas and also lymphomas). Differences in concentration of 20 of these metabolites were statistically significant between these brain tumour types. During the course of an extended 2D data acquisition the HRMAS technique itself affects sample analysis: glycine, glutathione and glycerophosphocholine all showed small concentration changes; analysis of the sample after HRMAS indicated structural damage that may affect subsequent histopathological analysis.
Conclusions: A number of small molecule metabolites have been identified as potential biomarkers of tumour
type that may enable development of more selective in-vivo 1H NMR acquisition methods for diagnosis and prognosis of brain tumours
The Distribution, Excitation and Formation of Cometary Molecules: Methanol, Methyl Cyanide and Ethylene Glycol
We present an interferometric and single dish study of small organic species
toward Comets C/1995 O1 (Hale-Bopp) and C/2002 T7 (LINEAR) using the BIMA
interferometer at 3 mm and the ARO 12m telescope at 2 mm. For Comet Hale-Bopp,
both the single-dish and interferometer observations of CH3OH indicate an
excitation temperature of 105+/-5 K and an average production rate ratio
Q(CH3OH)/Q(H2O)~1.3% at ~1 AU. Additionally, the aperture synthesis
observations of CH3OH suggest a distribution well described by a spherical
outflow and no evidence of significant extended emission. Single-dish
observations of CH3CN in Comet Hale-Bopp indicate an excitation temperature of
200+/-10 K and a production rate ratio of Q(CH3CN)/Q(H2O)~0.017% at ~1 AU. The
non-detection of a previously claimed transition of cometary (CH2OH)2 toward
Comet Hale-Bopp with the 12m telescope indicates a compact distribution of
emission, D<9'' (<8500 km). For the single-dish observations of Comet T7
LINEAR, we find an excitation temperature of CH3OH of 35+/-5 K and a CH3OH
production rate ratio of Q(CH3OH)/Q(H2O)~1.5% at ~0.3 AU. Our data support
current chemical models that CH3OH, CH3CN and (CH2OH)2 are parent nuclear
species distributed into the coma via direct sublimation off cometary ices from
the nucleus with no evidence of significant production in the outer coma.Comment: accepted for publication in Ap
A Bima Array Survey of Molecules in Comets Linear (C/2002 T7) and Neat (C/2001 Q4)
We present an interferometric search for large molecules, including methanol,
methyl cyanide, ethyl cyanide, ethanol, and methyl formate in comets LINEAR
(C/2002 T7) and NEAT (C/2001 Q4) with the Berkeley-Illinois-Maryland
Association (BIMA) array. In addition, we also searched for transitions of the
simpler molecules CS, SiO, HNC, HN13C and 13CO . We detected transitions of
methanol and CS around Comet LINEAR and one transition of methanol around Comet
NEAT within a synthesized beam of ~20''. We calculated the total column density
and production rate of each molecular species using the variable temperature
and outflow velocity (VTOV) model described by Friedel et al.(2005).Considering
the molecular production rate ratios with respect to water, Comet T7 LINEAR is
more similar to Comet Hale-Bopp while Comet Q4 NEAT is more similar to Comet
Hyakutake. It is unclear, however, due to such a small sample size, whether
there is a clear distinction between a Hale-Bopp and Hyakutake class of comet
or whether comets have a continuous range of molecular production rate ratios.Comment: Accepted for Publication in the Astrophysical Journa
Age systematics of two young en echelon Samoan volcanic trails
Author Posting. © American Geophysical Union, 2011. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 12 (2011): Q07025, doi:10.1029/2010GC003438.The volcanic origin of the Samoan archipelago can be explained by one of three models, specifically, by a hot spot forming over a mantle plume, by lithospheric extension resulting from complex subduction tectonics in the region, or by a combination of these two processes, either acting sequentially or synchronously. In this paper, we present results of 36 high-resolution 40Ar/39Ar incremental heating age analyses for the initial (submarine) phase of Samoan volcanoes, ranging from 13.2 Ma for the westernmost Samoan seamounts to 0.27 Ma in the eastern Samoan volcanic province. Taken as a whole, our new age data point to a hot spot origin for the shield-building volcanism in the Samoan lineament, whereby seamounts younger than 5 Ma are consistent with a model of constant 7.1 cm/yr plate motion, analogous to GPS measurements for the Pacific Plate in this region. This makes our new 40Ar/39Ar ages of the submarine basalts all older compared to recent absolute plate motion (APM) models by Wessel et al. (2008), which are based on the inversion of twelve independent seamount trails in the Pacific relative to a fixed reference frame of hot spots and which predict faster plate motions of around 9.3 cm/yr in the vicinity of Samoa. The Samoan ages are also older than APM models by Steinberger et al. (2004) taking into account the motion of hot spots in the Pacific alone or globally. The age systematics become more complicated toward the younger end of the Samoan seamount trail, where its morphology bifurcates into two en echelon subtracks, termed the VAI and MALU trends, as they emanate from two eruptive centers at Vailulu'u and Malumalu seamount, respectively. Spaced âŒ50 km apart, the VAI and MALU trends have distinct geochemical characters and independent but overlapping linear 40Ar/39Ar age progressions since 1.5 Ma. These phenomena are not unique to Samoa, as they have been observed at the Hawaiian hot spot, and can be attributed to a geochemical zoning in its underlying mantle source or plume. Moreover, the processes allowing for the emergence of two distinct eruptive centers in the Samoan archipelago, the stepped offset of these subtracks, and their slight obliqueness with respect to the overall seamount trail orientation may very well be controlled by local tectonics, stresses, and extension, also causing the rejuvenated volcanism on the main islands of Savai'i, Upolu, and Tutuila since 0.4 Ma.Financial support is provided by NSFâOCE 0002875 and
NSFâOCE 0351437
The Cold Big-Bang Cosmology as a Counter-example to Several Anthropic Arguments
A general Friedmann big-bang cosmology can be specified by fixing a
half-dozen cosmological parameters such as the photon-to-baryon ratio Eta, the
cosmological constant Lambda, the curvature scale R, and the amplitude Q of
(assumed scale-invariant) primordial density fluctuations. There is currently
no established theory as to why these parameters take the particular values we
deduce from observations. This has led to proposed `anthropic' explanations for
the observed value of each parameter, as the only value capable of generating a
universe that can host intelligent life. In this paper, I explicitly show that
the requirement that the universe generates sun-like stars with planets does
not fix these parameters, by developing a class of cosmologies (based on the
classical `cold big-bang' model) in which some or all of the cosmological
parameters differ by orders of magnitude from the values they assume in the
standard hot big-bang cosmology, without precluding in any obvious way the
existence of intelligent life. I also give a careful discussion of the
structure and context of anthropic arguments in cosmology, and point out some
implications of the cold big-bang model's existence for anthropic arguments
concerning specific parameters.Comment: 13 PRD-style pages, 2 postscript figures. Reference 26 corrected.
Accepted to Phys. Rev.
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