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Additional Causes (additional + cause)
Selected AbstractsIncreased temperature sensitivity of net DOC production from ombrotrophic peat due to water table draw-downGLOBAL CHANGE BIOLOGY, Issue 4 2009J. M. CLARK Abstract The production and release of dissolved organic carbon (DOC) from peat soils is thought to be sensitive to changes in climate, specifically changes in temperature and rainfall. However, little is known about the actual rates of net DOC production in response to temperature and water table draw-down, particularly in comparison to carbon dioxide (CO2) fluxes. To explore these relationships, we carried out a laboratory experiment on intact peat soil cores under controlled temperature and water table conditions to determine the impact and interaction of each of these climatic factors on net DOC production. We found a significant interaction (P < 0.001) between temperature, water table draw-down and net DOC production across the whole soil core (0 to ,55 cm depth). This corresponded to an increase in the Q10 (i.e. rise in the rate of net DOC production over a 10 °C range) from 1.84 under high water tables and anaerobic conditions to 3.53 under water table draw-down and aerobic conditions between ,10 and , 40 cm depth. However, increases in net DOC production were only seen after water tables recovered to the surface as secondary changes in soil water chemistry driven by sulphur redox reactions decreased DOC solubility, and therefore DOC concentrations, during periods of water table draw-down. Furthermore, net microbial consumption of DOC was also apparent at , 1 cm depth and was an additional cause of declining DOC concentrations during dry periods. Therefore, although increased temperature and decreased rainfall could have a significant effect on net DOC release from peatlands, these climatic effects could be masked by other factors controlling the biological consumption of DOC in addition to soil water chemistry and DOC solubility. These findings highlight both the sensitivity of DOC release from ombrotrophic peat to episodic changes in water table draw-down, and the need to disentangle complex and interacting controls on DOC dynamics to fully understand the impact of environmental change on this system. [source] Semaphorin 3A-Neuropilin-1 signaling regulates peripheral axon fasciculation and pathfinding but not developmental cell death patternsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 7 2010Corinna Haupt Abstract In early development, an excess of neurons is generated, of which later about half will be lost by cell death due to a limited supply of trophic support by their respective target areas. However, some of the neurons die when their axons have not yet reached their target, thus suggesting that additional causes of developmental cell death exist. Semaphorin 3A (Sema3A), in addition to its function as a guidance cue and mediator of timing and fasciculation of motor and sensory axon outgrowth, can also induce death of sensory neurons in vitro. However, it is unknown whether Neuropilin-1 (Npn-1), its binding receptor in axon guidance, also mediates the death-inducing activity. We show here that abolished Sema3A-Npn-1 signaling does not influence the cell death patterns of motor or sensory neurons in mouse during the developmental wave of programmed cell death. The number of motor and sensory neurons was unchanged at embryonic day 15.5 when this wave is concluded. Interestingly, the defasciculation of early motor and sensory projections that is observed in the absence of Sema3A or Npn-1 persists to postnatal stages. Thus, Sema3A-Npn-1 signaling plays an important role in the guidance and fasciculation of motor and sensory axons but does not contribute to the developmental elimination of these neurons. [source] The Impact of Generating Initial Hypothesis Sets of Different Sizes on the Quality of the Initial Set, and the Resulting Time Efficiency and Final Judgment AccuracyINTERNATIONAL JOURNAL OF AUDITING, Issue 1 2004Sudip Bhattacharjee This study examines the impact of generating initial hypothesis sets of different sizes on the quality of the hypotheses generated (i.e., the ability to consider both the direction and accounts that are over- or understated). We also examine the time efficiency, information search effectiveness, and the final judgment accuracy, conditional on the quality of the initial hypothesis set. Sixty auditors performed an analytical procedures task where they were asked to generate and test either a specific number of initial hypotheses (one, three, or six), or any number of hypotheses desired in order to uncover an error seeded in the financial statements. The results indicate that the three hypotheses group initially generated hypotheses of the highest quality and maintained the hypothesis quality after efficiently searching information and generating additional causes. The one hypothesis group improved the quality of their hypotheses only after generating and testing several causes. However, auditors who generated six hypotheses or any number desired (as in audit practice) considered hypotheses of lower quality in the initial set, and did not improve the hypotheses quality after going through the information search stage. These results suggest that the size of the initial hypothesis set can lead to differences in the gains that accrue from the hypothesis generation and information search stages of diagnostic decisions. [source] Abstracts of the 8th Meeting of the Italian Peripheral Nerve Study Group: 73JOURNAL OF THE PERIPHERAL NERVOUS SYSTEM, Issue 1 2003C Inglese Cryoglobulinemic neuropathy is probably the commonest form of vasculitic neuropathy in Mediterranean countries, as usually related to the widespread hepatitis C virus (HCV) infection. We describe the spectrum of manifestations in a large series of patients with cryoglobulinemic neuropathy, also analyzing the impact of comorbid factors, which are quite frequent in HCV-related mixed cryoglobulinemia. The cohort included 60 patients (10 men, 50 women) with peripheral neuropathy associated with mixed cryoglobulinemia as main or sole cause (type 2 in 36 cases, type 3 in 4, not typized in 20), HCV-related in all patients but 8 (3 men and 5 women). Median age of patients was 65 years (range 41,85), and median age at onset of neuropathy was 59 (range 40,84). Peripheral neuropathy represented an onset manifestation of mixed cryoglobulinemia in about half patients. The most frequent clinical pattern was pure sensory neuropathy in 40 patients, including 4 patients with prominent ataxia; sensory neuropathy was asymmetrical in distribution in 9 patients, and in 14 patients sensory action potentials (SAPs) of the sural nerve were normal, suggesting selective involvement of the small sensory fibers. The remaining patients had sensorimotor neuropathy (15 cases) and mononeuropathy multiplex (5 cases). Positive sensory symptoms and restless legs syndrome were the most common manifestations. Neurophysiological study showed axonal degeneration of varying severity in all patients. In 20 patients, additional causes of neuropathy were present, including type 2 diabetes (5 patients), glucose intolerance (6 patients), non-Hodgkin lymphoma (3 patients), and alcohol (2 patients). With respect with this subset of patients, in "pure" cryoglobulinemic neuropathy there was more often a pattern of sensory neuropathy (31/40 vs. 6/20; p = 0.001), with more frequent asymmetrical distribution (9 vs 0; p = 0.05) and small fiber involvement (11 vs 3). Severity of neuropathy, as judged on the basis of the Rankin scale and of neurophysiological changes, was similar in the two subgroups. Our study confirms that sensory neuropathy, often asymmetrical, is the most common clinical pattern in cryoglobulinemic neuropathy, and is consistently present in pure cryoglobulinemic neuropathy rather than in patients with other associated causes of neuropathy; in these latter, paradoxically, clinical and neurophysiological impairment seems not greater than in pure cryoglobulinemic neuropathy. [source] | ||||||||||