bluuebunny/crossref_metadata_2025_split huggingface dataset:
Early detection of declining populations using floor and ceiling models
Authors: Kshatriya Mrigesh , Cosner Chris , Van Jaarsveld Albert S. 
Published: March 2003

Summary

Within Caughley’s (1994) declining population paradigm for conservation, we develop a realistic method of detecting population changes using floor and ceiling population models.
A theoretical framework for detecting declining populations is presented and applied to four ungulate species from Kruger National Park, South Africa.
Census data are fitted to a non‐linear autoregressive population model. Based on this model two auxiliary models, called the floor and ceiling models, are derived. These models predict the upper and lower threshold densities (or abundance values) for the non‐linear population model.
Threshold floor and ceiling estimates can be used as a benchmark for monitoring population status. In particular, when abundance values (densities) tend to fall below the floor estimate, this may merit concern that a population is declining.
In conjunction with appropriate response by management, the presence of such an early warning system may prevent a population from becoming low in numbers, possibly making it less susceptible to stochastic processes and a less likely candidate for local extinction.
Community organization of tree species along soil gradients in a north‐eastern USA forest
Authors: Bigelow Seth W. , Canham Charles D. 
Published: March 2003

Summary

A study was carried out in oak‐northern hardwood forest in NW Connecticut USA involving measurements of growth, light and soil environment of saplings of six canopy trees that are strongly associated with particular soil types as adults. The objectives were to determine patterns of growth response along soil factor gradients, and to discriminate among modes of community organization (fundamental niche differentiation, shifting competitive hierarchy or continuum concept).
Relationships were found between tree species distributions and all measured soil factors (pH and exchangeable calcium, magnesium, potassium, aluminium, ammonium and nitrate).
Growth and light data were fitted to a nested series of functions based on the Michaelis‐Menten equation. For five of six species, likelihood‐ratio tests indicated that functions that incorporated pH or other soil factors predicted growth better than functions based only on light availability.
Species differed in the direction and strength of response to soil factors. Fraxinus americana had decreased growth on high‐magnesium soils, Acer rubrum had increased growth on high‐aluminium soils, Quercus rubra and Fagus grandifolia had increased growth on high‐calcium soils and Tsuga canadensis had increased growth on high‐nitrate soils.
Growth responses were consistent with either fundamental niche differentiation and continuum concept (Acer rubrum), shifting competitive hierarchy and continuum concept (Fagus grandifolia, Quercus rubra and Tsuga canadensis) or were not consistent with any theory (Acer saccharum and Fraxinus americana).
Because saplings are associated with the same soil‐types as mature trees, further studies in this system should focus on earlier stages of the plant life cycle: dispersal, germination and seedling establishment.
Near field optical microscopy in aqueous solution: implementation and characterization of a vibrating probe
Authors: Mannelquist A. , Iwamoto H. , Szabo G. , Shao Z. 
Published: March 2003

SummaryNear field optical microscopy (NSOM) is one of the possible solutions to circumvent the diffraction limit, but the control of the optical probe in solution has been a technical challenge for practical applications. Most recently, it has been shown that the pipette used in the scanning ion conductance microscope can be modified to form a high resolution near field optical probe. When combined with a novel distance modulation mechanism, a robust near field microscope can be constructed for operation in aqueous solution. In this paper, we present technical details of this design and a further characterization of the NSOM system for imaging in solution. Fundamental limitations of this approach in comparison to other systems are also discussed. Based on the current technology, it is concluded that better than 50 nm resolution should be achievable with this technique for fluorescence, as well as fluorescence resonance energy transfer, imaging of biological specimens.
Sequential induction of embryonic and adult forms of glutamic acid decarboxylase during in vitro‐induced neurogenesis in cloned neuroectodermal cell‐line, NE‐7C2
Authors: Varju Patricia , Katarova Zoya , Madarász Emília , Szabó Gábor 
Published: March 2003

AbstractThe expression of different forms of glutamate decarboxylases and GABA was investigated in the course of retinoic acid‐induced neuronal differentiation of NE‐7C2 cell‐line established from brain vesicles of 9‐day‐old mouse embryos lacking functional p53 gene. Non‐induced NE‐7C2 cells expressed embryonic GAD mRNAs with a low level of embryonic GAD25 protein and did not contain detectable amounts of GABA. Addition of 10−6m retinoic acid induced the expression of N‐tubulin and a significant increase in the level of embryonic GAD messages and GAD25 protein in early stage differentiating neurones. The enzymatically active embryonic GAD44 was detected at later stages of induction in neurone‐like cells and showed a maximum of expression at the time of neurite elongation and network formation. With the advance of neuronal maturation, the expression of embryonic forms declined while the adult GAD65 and GAD67 transcripts became dominant. GABA‐containing neurones were first demonstrated on the sixth day of induction coinciding with the peak of GAD44 expression and the beginning of GAD65 expression. The sequential induction of different GAD forms and the stage‐dependent GABA synthesis in NE‐7C2 cells is highly reminiscent of the temporal pattern found in vivo and suggests that these processes might be involved in the differentiation of neuronal progenitors.
Effects of serotine receptors agonists, TFMPP and CGS12066B, on regional serotonin synthesis in the rat brain: an autoradiographic study
Authors: Tohyama Yoshihiro , Yamane Fumitaka , Fikre Merid Maraki , Blier Pierre , Diksic Mirko 
Published: March 2003

AbstractThe effects of acute and repeat administration of the serotonin (5‐HT)1 agonists TFMPP [N‐(3‐trifluoromethyl)phenylpiperazine hydrochloride] and CGS12066B [7‐trifluoromethyl‐4‐	(4‐methyl‐1‐piperazinyl)pyrrolo[1,2‐a]‐quinoxaline dimaleate] were evaluated on 5‐HT synthesis rates using the α‐[14C]methyl‐l‐tryptophan (α‐MTrp) autoradiographic method. In the acute treatment study, TFMPP (10 mg/kg) and CGS12066B (5 mg/kg) were injected intraperitoneally 30 min before an α‐MTrp injection. In an acute study TFMPP reduced overall brain 5‐HT synthesis, in the dorsal and median raphe, and in almost all of their projection areas, with the exception of the parietal, sensory‐motor, and frontal cortices, the accumbens nucleus, and the caudate. Acute CGS12066B treatment did not have overall significant effect, but the rates did decrease in the cell body areas of 5‐HT neurons. In a 7‐day treatment with TFMPP (10 mg/kg/day) or CGS12066B	(5 mg/kg/day), the 5‐HT synthesis rates (24 h after last dose) decrease, with both compounds, in almost all of the nerve terminal structures. TFMPP reduced the synthesis in the dorsal and median raphe, while CGS12066B reduced it only in the dorsal raphe. This data suggests that after a 7‐day treatment with TFMPP and CGS12066B, the rate of 5‐HT synthesis in the dorsal raphe is restored and is reduced in many projection areas. The observed effects in the 7‐day treatment could also be related to actions through the postsynaptic 5‐HT1B sites and/or other 5‐HT receptors since this compounds have limited selectivity.
Effects of estrogen treatment on glutamate uptake in cultured human astrocytes derived from cortex of Alzheimer's disease patients
Authors: Liang Zhe , Valla Jon , Sefidvash‐Hockley Sepideh , Rogers Joseph , Li Rena 
Published: March 2003

AbstractEstrogen is thought to play a protective role against neurodegeneration through a variety of mechanisms including the activation of growth factors, the control of synaptic plasticity, and the reduction of response to various insults, such as iron and glutamate. Increasing evidence indicates an increased level of extracellular glutamate and a down‐regulation of glutamate transporters in Alzheimer's disease (AD). In this study, we show that glutamate uptake in astrocytes derived from Alzheimer's patients is significantly lower than that from non‐demented controls. Estrogen treatment increases glutamate uptake in a dose‐dependent pattern. Two glutamate transporters, GLT‐1 and GLAST, are expressed in the astrocytes. Up‐regulation of the glutamate transporters is induced by estrogen treatment in AD astrocytes only. Our data suggest that the action of estrogen on glutamate uptake by astrocytes might contribute to its potential neuroprotective role in AD.
A direct role of the homeodomain proteins Phox2a/2b in noradrenaline neurotransmitter identity determination
Authors: Seo Hyemyung , Hong Seok Jong , Guo Su , Kim Hee‐Sun , Kim Chun‐Hyung , Hwang Dong‐Youn , Isacson Ole , Rosenthal Arnon , Kim Kwang‐Soo 
Published: March 2003

AbstractDevelopment of noraderenergic (NA) neurons in the vertebrate brain is dependent on the homeodomain proteins Phox2a and 2b. Here, we show that Phox2a directly controls the NA identity by activating NA‐synthesizing dopamine β‐hydroxylase (DBH) gene. Single point mutations in the homeodomain of Phox2a resulted in a failure to transactivate the DBH promoter in vitro and resulted in the loss of NA neurons in vivo. In addition, injection of Phox2a‐specific antisense oligonucleotide induced the loss of NA neurons in developing zebrafish. Phox2a and 2b activate the DBH promoter and bind to three domains (PBD1–3). PBD1 is composed of two overlapping sites with which monomers of Phox2a can interact. In contrast, PBD2 and 3 interact with the dimeric form of Phox2a. Mutations in three or four, but not one or two, of the binding sites completely abolished activation of the DBH promoter by Phox2a or 2b, while the conversion of PBD3 to a consensus motif (ATTA) improved the DBH promoter activity by > 10‐fold. Taken together, these findings establish that Phox2a and 2b control the development of NA neurons in part by directly transactivating DBH transcription through interactions with four binding sites clustered in the proximal promoter.
Fra‐1 substitutes for c‐Fos in AP‐1‐mediated signal transduction in retinal apoptosis
Authors: Wenzel Andreas , Iseli Hans Peter , Fleischmann Alexander , Hafezi Farhad , Grimm Christian , Wagner Erwin F. , Remé Charlotte E. 
Published: March 2003

AbstractLack of the AP‐1 member c‐Fos protects photoreceptors against light‐induced apoptosis, a model for retinal degeneration. In mice, light damage increases the activity of the transcription factor AP‐1, while pharmacological suppression of AP‐1 prevents apoptosis, suggesting the involvement of pro‐apoptotic AP‐1 target genes. Recently, however, it was shown that photoreceptors expressing Fra‐1 in place of c‐Fos (FosFosl1/Fosl1) are apoptosis competent despite the lack of transactivation domains in Fra‐1. Here, we show that morphological features of light‐induced apoptosis were indistinguishable in FosFosl1/Fosl1 and wild‐type mice. Furthermore, light exposure comparably increased AP‐1 activity in both genotypes. Opposite to wild‐type mice, Fra‐1, but not c‐Fos, was detectable in AP‐1 complexes of FosFosl1/Fosl1 mice. Importantly, AP‐1 responsiveness for glucocorticoid receptor‐mediated inhibition was preserved in FosFosl1/Fosl1 mice. Thus, Fra‐1 takes over for c‐Fos in pro‐ and anti‐apoptotic signal transduction. As Fra‐1 lacks transactivation domains, AP‐1 may not induce, but rather suppress genes in retinal light damage.
Plant hormones and the control of physiological processes
Authors: Weyers Jonathan D. B. , Paterson Neil W. 
Published: March 2003

SummaryThis review examines contemporary views of the role of plant hormones in the control of physiological processes. Past and present difficulties with nomenclature encapsulate the problems inherent in using the ‘classic’ hormone concept in plants, with their distinctive multicellular organization. Chemical control may be a more relevant notion. However, control may also reside in the responding tissue via changes in sensitivity, or as combined control, where response is dictated by both sensitivity and concentration. Criteria for demonstrating these modes of action are reviewed, as well as frameworks for deciding whether hormone transport is involved. Problems of measuring relevant hormone concentrations are discussed. Methods for measuring and comparing tissue sensitivity to hormones are outlined and relative control is introduced as a means of assessing the importance of hormonal control against a background of other influences. While animals and plants appear to have coinherited homologueous intracellular signalling systems, at the whole organism level modes of hormone action may diverge. It is postulated that the synthesis‐transport‐action mechanism of action may be just one of several possible ways that phytohormones could control physiological processes. Twelve separate roles are discussed, and it is suggested that some of these could operate simultaneously to the plant’s advantage.ContentsSummary 375I.Introduction376II.The history of the hormone concept in plant systems376III.Issues of nomenclature380IV.The need for sound conceptual frameworks in plant hormone research382V.Development of criteria for chemical control384VI.Identification and quantitative analysis of plant hormones387VII.Hormone transport in plants389VIII.Hormone sensitivity and its quantification390IX.Roles of receptors, second messengers and signal amplification in hormone sensitivity changes393X.Relative control as a pivotal concept395XI.Diversity of physiological roles for chemical influences in plants397XII.Concluding remarks400Acknowledgements402References402
Limit Loads for Axially Loaded Cylinders Having Full Circumferential Cracks: Experimental, Analytical and Numerical Studies
Authors: Lynch M. A. , Moreton D. N. , Moffat D. G. 
Published: March 2003

Abstract:The limit load of an axially loaded cylinder, containing a fully circumferential part‐penetrating crack, has been established by three techniques. These were a stress analysis to find a lower bound to the limit load, a finite element analysis and an experimental programme which utilised extensively strain‐gauged precision‐made specimens. This article reports the results of these approaches and demonstrates the value of each.
Naturally acquired immunoglobulin (Ig)G subclass antibodies to crude asexual Plasmodium falciparum lysates: evidence for association with protection for IgG1 and disease for IgG2
Authors: Ndungu Francis M. , Bull Peter C. , Ross Amanda , Lowe Brett S. , Kabiru Ephantus , Marsh Kevin 
Published: March 2003

SummaryThere is longstanding evidence for a role of immunoglobulin (Ig)G in protection against malarial disease and infection. IgG1 and IgG3 have been shown to be particularly efficient at associating with monocytes in potentially protective mechanisms (i.e. antibody‐dependent cellular inhibition, opsonization and phagocytosis). Conversely, there is some evidence that IgG2 (and possibly IgG4) antibodies may be antagonistic to this protection. The protective effect of IgG subclass antibody activity present before the beginning of a malaria transmission season (preseason antibody levels) against severe malaria has not been tested in longitudinal studies. We measured IgG class and subclass antibody levels specific to crude Plasmodium falciparum lysates by enzyme linked immunosorbent assay in a case–control study of 76 children on the coast of Kenya. The mean optical density values for both IgG class and subclass antibodies were not significantly different between the children who developed severe malaria and those who remained healthy during an observation period of two malaria transmission seasons. However, elevated levels of IgG1 in relation to levels of IgG2 and IgG4 antibodies were associated with protection from severe malaria (P = 0·02). Conversely, elevated levels of IgG2 in relation to IgG1 and IgG3 antibodies were associated with a higher risk of developing severe malaria (P = 0·006).
Effect of three root canal sealers on the retentive strength of endodontic posts luted with a resin cement
Authors: Hagge M. S. , Wong R. D. M. , Lindemuth J. S. 
Published: March 2003

Abstract Hagge MS, Wong RDM, Lindemuth JS. Effect of three root canal sealers on the retentive strength of endodontic posts luted with a resin cement. International Endodontic Journal, 35, 372–378, 2002.Aim  This investigation examined what effect three different sealers had on retention of endodontic posts (Parapost) luted with a resin cement (Panavia 21 OP).Methodology Sixty‐four single‐rooted teeth were decoronated, filed, cleaned, and shaped with a size 5 Gates–Glidden drill and 0.12 taper G.T. rotary instrumentation (Dentsply/Tulsa Dental). Teeth were then divided into four groups of 16 each. Group 1 was not obturated, and served as a control. The other three groups were obturated with gutta‐percha using a different sealer for each group. Group 2 used a eugenol containing sealer (Kerr Pulp Canal Sealer), group 3 a resin sealer (AH‐26), and group 4 a calcium hydroxide sealer (Sealapex). After 1 week’s storage at 100% humidity, 10‐mm deep post spaces were prepared with a size 6 Gates–Glidden drill, and size 5 Paraposts were cemented. Following 48 h of storage, samples were mounted in a PVC pipe with acrylic, and the posts were removed vertically using a universal testing machine at 1 mm min−, with data recorded in kilograms.Results The mean values of force required to remove the posts were: group 1 = 61.80, SD = 16.21; group 2 = 43.14, SD = 14.66; group 3 = 48.54, SD = 17.84; group 4 = 53.52, SD = 18.77. Using anova and Bonferroni tests, group 1 demonstrated significantly greater mean retention strength values than group 2, but no other significant differences existed between groups.Conclusion The chemical formulation of root canal sealers did not significantly affect the retention of endodontic posts luted with resin cement.
Endodontic implications of the maxillary sinus: a review
Authors: Hauman C. H. J. , Chandler N. P. , Tong D. C. 
Published: March 2003

AbstractThe anatomical and clinical significance of the maxillary sinus in relation to conventional and surgical endodontic therapy is considered. The discussion includes a review on the development, anatomy and physiology of the maxillary sinus, the diagnostic evaluation of the sinus and the differential diagnosis of sinusitis. Endodontic implications of the maxillary sinus include extension of periapical infections into the sinus, the introduction of endodontic instruments and materials beyond the apices of teeth in close proximity to the sinus and the risks and complications associated with endodontic surgery.
Long‐term reliability and observer comparisons in the radiographic diagnosis of periapical disease
Authors: Molven O. , Halse A. , Fristad I. 
Published: March 2003

AbstractAim The aim of this study was to evaluate and compare the long‐term diagnostic consistency of two examiners, an endodontist and a radiologist, and to make comparisons with findings recorded by an observer with more recent scientific and clinical experience in endodontics.Methodology Three groups, each consisting of 20 full mouth series of intraoral radiographs, with 79, 93 and 85 endodontically‐treated roots, respectively, were successively evaluated for periapical disease. Evaluations were at first performed separately by the three observers. Disagreement and difficult, borderline cases were subjected to joint evaluation. Intra‐ and interexaminer comparisons were made. For two of the observers the observations were compared with findings recorded several years before for the same cases in the same radiographs.Results The intra‐ and interobserver long‐term reliability of the two original examiners resulted in 83% overall agreement, the kappa values were 0.54, 0.57 and 0.53. Comparisons between all three observers disclosed 82%, 85% and 86% agreement and kappa values 0.55, 0.58 and 0.60. The joint evaluations and decisions did not indicate a dominating influence from any of the observers.Conclusions The long‐term reliability of the two original observers was judged as being satisfactory. All three observers judged the overall disease status of the material in the same way. The joint discussions of selected cases might reduce observer variation to an acceptable level, avoid a number of false recordings and increase the reliability and validity of the findings.
Neoproterozoic high‐pressure/low‐temperature metamorphic rocks in the Avalon terrane, southern New Brunswick, Canada
Authors: White C. E. , Barr S. M. , Jamieson R. A. , Reynolds P. H. 
Published: March 2003

AbstractHigh‐P/low‐T metamorphic rocks of the Hammondvale metamorphic suite (HMS) are exposed in an area of 10 km2 on the NW margin of the Caledonian (Avalon) terrane in southern New Brunswick, Canada. The HMS is in faulted contact on the SE with c. 560–550 Ma volcanic and sedimentary rocks and co‐magmatic plutonic units of the Caledonian terrane. The HMS consists of albite‐ and garnet‐porphyroblastic mica schist, with minor marble, calc‐silicate rocks and quartzite. Pressure and temperature estimates from metamorphic assemblages in the mica schist and calc‐silicate rocks using TWQ indicate that peak pressure conditions were 12.4 kbar at 430 °C. Peak temperature conditions were 580 °C at 9.0 kbar. 40Ar/39Ar muscovite ages from three samples range up to 618–615 Ma, a minimum age for high‐P/low‐T metamorphism in this unit. These ages indicate that the HMS is related to the c. 625–600 Ma subduction‐generated volcanic and plutonic units exposed to the SE in the Caledonian terrane. The ages are also similar to those obtained from detrital muscovite in a Neoproterozoic‐Cambrian sedimentary sequence in the Caledonian terrane, suggesting that the HMS was exposed by latest Neoproterozoic time and supplied detritus to the sedimentary units. The HMS is interpreted to represent a fragment of an accretionary complex, similar to the Sanbagawa Belt in Japan. It confirms the presence of a major cryptic suture between the Avalon terrane sensu stricto and the now‐adjacent Brookville terrane.
Systematics of Schistopterini (Diptera: Tephritidae: Tephritinae), with descriptions of new genera and species
Authors: Freidberg Amnon 
Published: March 2003

Abstract. The systematics of tribe Schistopterini (Diptera: Tephritidae) is reviewed and discussed, and a key is given to the fourteen current genera, of which four are new. A cladogram of the type species of the genera plus all other species of one of the new genera (Microtreta) is presented, supporting the monophyly of Microtreta.The new genera include Calloptera (type species Rhabdochaeta asteria Hendel), Microtreta (type species Microtreta fini, sp.n.), Melanopterella (type species Rhabdochaeta nigra Bezzi) and Schistotephritis (type species Camaromyia acrophthalma Bezzi). Microtreta is treated comprehensively; its constituents, deemingi, fini, frontale, jeffreyi and longicornis (all new species), are described from East Africa and the Arabian Peninsula. Host plants, all of genus Vernonia (Asteraceae), are recorded for the four East African species. Characters of immature stages are described for M. longicornis. Eighteen new combinations are made.