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Significant Relief (significant + relief)
Selected AbstractsBehavioural responses of a south-east Australian floodplain fish community to gradual hypoxiaFRESHWATER BIOLOGY, Issue 3 2007DALE G. MCNEIL Summary 1. Hypoxic conditions occur frequently during hot, dry summers in the small lentic waterbodies (billabongs) that occur on the floodplains of the Murray-Darling River system of Australia. Behavioural responses to progressive hypoxia were examined for the native and introduced floodplain fish of the Ovens River, an unregulated tributary of the Murray River in south-east Australia. 2. Given the high frequency of hypoxic episodes in billabongs on the Ovens River floodplain, it was hypothesised that all species would exhibit behaviours that would confer a degree of hypoxia-tolerance. Specifically, it was hypothesised that as hypoxia progressed, gill ventilation rates (GVRs) would increase and aquatic surface respiration (ASR) would become increasingly frequent. Fish were subjected to rapid, progressive hypoxia from normoxia to anoxia in open tanks. 3. All tested species exhibited behaviours consistent with their use of potentially hypoxic habitats. As hypoxia progressed, GVRs increased and all species, with the exception of oriental weatherloach, began to switch increasingly to ASR with 90% of individuals using ASR at various oxygen concentrations below 1.0 mg O2 L,1. Australian smelt, redfin perch and flat-headed galaxias were the first three species to rise to ASR, with 10% of individuals using ASR by 2.55, 2.29 and 2.21 mg O2 L,1 respectively. Goldfish and common carp were the last two species to rise to ASR, with 10% of individuals using ASR by 0.84 and 0.75 mg O2 L,1 respectively. In contrast to other species, oriental weatherloach largely ceased gill ventilation and used air-gulping as their primary means of respiration during severe hypoxia and anoxia. 4. Australian smelt, redfin perch and flat-headed galaxias were unable to maintain ASR under severe hypoxia, and began exhibiting erratic movements, termed terminal avoidance behaviour, and loss of equilibrium. All other species continued to use ASR through severe hypoxia and into anoxia. Following a rise to ASR, GVRs either remained steady or decreased slightly indicating partial or significant relief from hypoxic stress for these hypoxia-tolerant species. 5. Behavioural responses to progressive hypoxia amongst the fish species of the Ovens River floodplain indicate a generally high level of tolerance to periodic hypoxia. However, species-specific variation in hypoxia-tolerance may have implications for community structure of billabong fish communities following hypoxic events. [source] Archaeological mounds in Marajó Island in northern Brazil: A geological perspective integrating remote sensing and sedimentologyGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 1 2009Dilce de Fátima Rossetti Earthen mounds with archaeological artifacts have been well known in Marajó Island since the 19th century. Their documented dimensions are impressive, e.g., up to 20 m high, and with areas as large as 90 ha. The mounds, locally known as tesos, impose a significant relief on the very low-lying landscape of this region, which averages 4 to 6m above present sea level. These features have been traditionally interpreted as artificial constructions of the Marajoara culture, designed for defense, cemetery purposes, or escape from flooding. Here, we provide sedimentological and geomorphological data that suggest an alternative origin for these structures that is more consistent with their monumental sizes. Rather than artificial, the Marajoara tesos seem to consist of natural morphological features related to late Pleistocene and Holocene fluvial, and possibly tidal-influenced, paleochannels and paleobars that became abandoned as depositional conditions changed through time. Although utilized and modified by the Marajoara since at least 2000 years ago, these earthen mounds contain a significant non-anthropogenically modified sedimentary substratum. Therefore, the large Marajoara tesos are not entirely artificial. Ancient Marajoara cultures took advantage of these natural, preexisting elevated surfaces to base their communities and develop their activities, locally increasing the sizes of these fluvial landforms. This alternative interpretation suggests less cumulative labor investment in the construction of the mounds and might have significant implications for reconstructing the organization of the Marajoara culture. © 2009 Wiley Periodicals, Inc. [source] Sedimentary and crustal structure from the Ellesmere Island and Greenland continental shelves onto the Lomonosov Ridge, Arctic OceanGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 1 2010H. Ruth Jackson SUMMARY On the northern passive margin of Ellesmere Island and Greenland, two long wide-angle seismic reflection/refraction (WAR) profiles and a short vertical incident reflection profile were acquired. The WAR seismic source was explosives and the receivers were vertical geophones placed on the sea ice. A 440 km long North-South profile that crossed the shelf, a bathymetric trough and onto the Lomonosov Ridge was completed. In addition, a 110 km long profile along the trough was completed. P -wave velocity models were created by forward and inverse modelling. On the shelf modelling indicates a 12 km deep sedimentary basin consisting of three layers with velocities of 2.1,2.2, 3.1,3.2 and 4.3,5.2 km s,1. Between the 3.1,3.2 km s,1 and 4.3,5.2 km s,1 layers there is a velocity discontinuity that dips seaward, consistent with a regional unconformity. The 4.3,5.2 km s,1 layer is interpreted to be Palaeozoic to Mesozoic age strata, based on local and regional geological constraints. Beneath these layers, velocities of 5.4,5.9 km s,1 are correlated with metasedimentary rocks that outcrop along the coast. These four layers continue from the shelf onto the Lomonosov Ridge. On the Ridge, the bathymetric contours define a plateau 220 km across. The plateau is a basement high, confirmed by short reflection profiles and the velocities of 5.9,6.5 km s,1. Radial magnetic anomalies emanate from the plateau indicating the volcanic nature of this feature. A lower crustal velocity of 6.2,6.7 km s,1, within the range identified on the Lomonosov Ridge near the Pole and typical of rifted continental crust, is interpreted along the entire line. The Moho, based on the WAR data, has significant relief from 17 to 27 km that is confirmed by gravity modelling and consistent with the regional tectonics. In the trough, Moho shallows eastward from a maximum depth of 19,16 km. No indication of oceanic crust was found in the bathymetric trough. [source] Cellular and behavioural effects of the adenosine A2a receptor antagonist KW-6002 in a rat model of l -DOPA-induced dyskinesiaJOURNAL OF NEUROCHEMISTRY, Issue 6 2003M. Lundblad Abstract We have examined the ability of KW-6002, an adenosine A2a antagonist, to modulate the dyskinetic effects of l -DOPA in 6-hydroxydopamine-lesioned rats. In animals rendered dyskinetic by a previous course of l -DOPA treatment, KW-6002 did not elicit any abnormal involuntary movements on its own, but failed to reduce the severity of dyskinesia when coadministered with l -DOPA. A second experiment was undertaken in order to study the effects of KW-6002 in l -DOPA-naive rats. Thirty-five animals were allotted to four groups to receive a 21-day treatment with: (i) KW-6002 (10 mg/kg/day); (ii) l -DOPA (6 mg/kg/day) i.p.; (iii) KW-6002 plus l -DOPA (same doses as above) or (iv) vehicle. Chronic treatment with KW-6002-only produced a significant relief of motor disability in the rotarod test in the absence of any abnormal involuntary movements. Combined treatment with l -DOPA and KW-6002 improved rotarod performance to a significantly higher degree than did each of the two drugs alone. However, this combined treatment induced dyskinesia to about the same degree as did l -DOPA alone. In situ hybridization histochemistry showed that KW-6002 treatment alone caused an approximately 20% reduction in the striatal levels of preproenkephalin mRNA, whereas neither the coadministration of KW-6002 and l -DOPA nor l -DOPA alone significantly altered the expression of this transcript in the dopamine-denervated striatum. Either alone or in combination with l -DOPA, KW-6002 did not have any modulatory effect on prodynorphin mRNA expression or FosB/,FosB-like immunoreactivity in the dopamine-denervated striatum. These results show that monotreatment with an adenosine A2a receptor antagonist can relieve motor disability without inducing behavioural and cellular signs of dyskinesia in rats with 6-hydroxydopamine lesions. Cotreatment with KW-6002 and l -DOPA potentiates the therapeutic effect but not the dyskinesiogenic potential of the latter drug. [source] Median Arcuate Ligament Syndrome,A Novel Treatment Using an Intrathecal Morphine Pump to Relieve Intractable Visceral PainPAIN PRACTICE, Issue 2 2008Oren T. Guttman MD ,,Abstract Purpose: Median arcuate ligament syndrome, which presents with intractable visceral pain, is difficult to both diagnose and treat. This case report describes the first use of an intrathecal morphine pump as an effective therapeutic intervention. Clinical features: We describe a 39-year-old female who presented with a four-year history of misdiagnosed debilitating abdominal pain. After multiple failed attempts at medical management and surgeries, a trial of intrathecal narcotics provided significant relief. Six months after insertion of an intrathecal morphine pump, the patient was pain-free and had resumed all activities of daily living. Conclusion: The use of an intrathecal narcotic pump should be considered for treatment of patients with intractable visceral pain secondary to median arcuate ligament syndrome.,, [source] Coincidence of conchachoanal polyp and complete mulberry hypertrophy of inferior conchaTHE LARYNGOSCOPE, Issue 4 2009Davut Akduman MD Abstract We report two unique cases of 50- and 28-year-old Turkish men with coincidence of conchachoanal polyp and mulberry hypertrophy of the inferior concha. We operated on both cases with endoscopic stripping of the polypoid tissue while preserving the periosteum and healthy mucosa of the inferior nasal concha. The polypoid tile of the left inferior nasal concha was resected in the case with mulberry hypertrophy at only the tail of the concha. Both cases reported significant relief of symptoms after the operations. Laryngoscope, 2009 [source] | ||||||||||||||||