Schizophrenia patients have higher scores on neurological soft-signs (NSS) and show greater deficits on a variety of neuropsychological tests than normal control subjects and mixed groups of psychiatric patients. Among chronic schizophrenia patients it is unclear which of these types of deficits most strongly differentiates patients who remain consistently symptomatic in spite of treatment with several conventional neuroleptics (nonresponders) as compared with relapsing chronic schizophrenia patients who improve substantially with treatment (relative responders). In this study, 25 nonresponders and 20 relative responders to conventional neuroleptics were compared on an NSS battery and a limited number of neuropsychological tests, which evaluated deficits influenced by functioning of frontal and nonfrontal brain areas. NSS scores showed the largest difference between relative responders and nonresponders, and statistical analyses suggested that NSS scores were the strongest differentiator between the two groups of chronic schizophrenia patients. Scores differentiating the two groups involved deficits influenced by both frontal and nonfrontal functioning. A predominance of negative symptoms in the current clinical picture was highly correlated with high NSS scores.

L-ascorbic acid, commonly known as vitamin C, is a ubiquitous 6-carbon carbohydrate characterized by its ability to scavenge free radicals. In enteric bacteria, L-ascorbate can be utilized as a nutrient using the UlaABCDEF and UlaG-UlaRpathway under anaerobic conditions. In this study, we identified homologs of the Ula system within Vibrio cholerae and showed that V. cholerae is able to utilize L-ascorbate as an energy source. Growth pattern assays of a ulaG in-frame deletion mutant demonstrated that ulaG is essential for L-ascorbate fermentation. Expression analysis showed that ula catabolism and transport genes were significantly induced in cells grown in the presence of L-ascorbate compared to glucose and these genes were also highly induced during growth on intestinal mucus. In in vitro growth competition assays, the ulaG mutant was outcompeted by wild type when grown in intestinal mucus suggesting the Ula system could be important for fitness. Within the ula operon in V. cholerae and all Vibrio species a homology of ORF VCA0243 is present that encodes a pyridoxal phosphate (PLP) phosphatase. This enzyme in E. coli, converts the active form of vitamin B6 PLP to its inactive form pyridoxal (PL). In V. splendidus and related species, the aerobic and anaerobic L-ascorbate pathway genes cluster together and both systems contain a PLP phosphatase. An in-frame deletion mutant of vca0243 resulted in a growth defect in L-ascorbate fermentation as well as additional carbon and amino acid sources indicating a role in cellular metabolism. Phylogenetic analysis of UlaG and UlaD suggested the region was acquired by horizontal gene transfer.ImportanceL-ascorbate is a carbohydrate present in the human intestine, available for microbial consumption and several enteric species have been shown to utilize this compound as an energy source. We demonstrated that L-ascorbate fermentation genes are also present among marine bacteria from the family Vibrionaceae and that the human pathogen V. cholerae can ferment L-ascorbate as an energy source. Within the Ula operon in all Vibrionaceae, a putative pyridoxal phosphate phosphatase was present that was required for L-ascorbate fermentation and cellular metabolism in general. The Ula system was present among a limited number of genera within Vibrionaceae; Vibrio, Aliivibrio and Photobacterium and showed an evolutionary history consistent with horizontal transfer between genera and species.

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In this paper we derive equations describing the performance of various adaptive echo canceller configurations operating in a linear, time-invariant environment.We relate the parameters in these equa tions to measurable environmental factors, discuss their effect on per formance, and verify the results empirically.In general, the performance of an echo canceller cannot be exactly predicted for speech inputs. Therefore, the derived equations assume a stationary constant power random input. However, it is shown that the results obtained in this manner give useful estimates of the per formance to be expected with speech inputs. The similarities and differences of the results for a constant power random input and speech input are discussed in detail.

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