93 research outputs found
An RNA interference knock-down of nitrate reductase enhances lipid biosynthesis in the diatom Phaeodactylum tricornutum
No full textWhen diatoms are stressed for inorganic nitrogen they remodel their intermediate metabolism and redirect carbon towards lipid biosynthesis. However, this response comes at a significant cost reflected in decreased photosynthetic energy conversion efficiency and growth. Here we explore a molecular genetics approach to restrict the assimilation of inorganic nitrogen by knocking down nitrate reductase (NR). The transformant strain, NR21, exhibited about 50% lower expression and activity of the enzyme but simultaneously accumulated over 40% more fatty acids. However, in contrast to nitrogen-stressed wild-type (WT) cells, which grow at about 20% of the rate of nitrogen-replete cells, growth of NR21 was only reduced by about 30%. Biophysical analyses revealed that the photosynthetic energy conversion efficiency of photosystem II was unaffected in NR21; nevertheless, the plastoquinone pool was reduced by 50% at the optimal growth irradiance while in the WT it was over 90% oxidized. Further analyses reveal a 12-fold increase in the glutamate/glutamine ratio and an increase NADPH and malonyl-CoA pool size. Transcriptomic analyses indicate that the knock down resulted in changes in the expression of genes for lipid biosynthesis, as well as the expression of specific transcription factors. Based on these observations, we hypothesize that the allocation of carbon and reductants in diatoms is controlled by a feedback mechanism between intermediate metabolites, the redox state of the plastid and the expression and binding of transcription factors related to stress responses.Peer reviewe
Response Variability and Timing Precision of Neuronal Spike Trains In Vivo
No full text Reich, Daniel S., Jonathan D. Victor, Bruce W. Knight, Tsuyoshi Ozaki, and Ehud Kaplan. Response variability and timing precision of neuronal spike trains in vivo. J. Neurophysiol. 77: 2836–2841, 1977. We report that neuronal spike trains can exhibit high, stimulus-dependent temporal precision even while the trial-to-trial response variability, measured in several traditional ways, remains substantially independent of the stimulus. We show that retinal ganglion cells and neurons in the lateral geniculate nucleus (LGN) of cats in vivo display both these aspects of firing behavior, which have previously been reported to be contradictory. We develop a simple model that treats neurons as “leaky” integrate-and-fire devices and show that it, too, can exhibit both behaviors. We consider the implications of our findings for the problem of neural coding. </jats:p
The Story of Ehud and Eglon in Judges 3:12-30. A Literary Pearl as a Theological Stumbling Block
No full textMaking use of numerous stylistic devices and playing with words, the author of Judg 3:12-30 has succeeded in creating a masterpiece of literature that challenges its reader. Moreover and simultaneously, this story, that narrates the brutal murder of king Eglon by the Israelite Ehud, is very problematic from a theological perspective. The present article offers firstly an analysis of Judg 3:12-20 and subsequently demonstrates how a specific and often-overlooked aspect of the violent nature of the text – after all, king Eglon has been utilized by YHWH to restore obedience among the Israelites – holds a key to unlocking the theological intention of this text
The genetic basis of persistence and recovery in stuttering
No full textThe purpose of this study was to elaborate on genetic perspectives of stuttering with reference to recovery and chronicity in children. Past research has provided evidence of a genetic factor in the transmission of susceptibility to stuttering, but factors governing persistence and recovery have not been as yet identified.Immediate and extended families of 66 stuttering probands were investigated to determine frequencies of persistent and recovered stuttering. Pedigree analysis and segregation analysis were utilized to examine patterns of heritability.The following questions were investigated: (1) Is there a sex effect in recovery from stuttering? This hypothesis examined the notion that females have a greater chance of recovery than do males, leading to the changing sex ratio from approximately 2:1 males to females close to onset of the disorder, to 4 or 5:1 in adulthood. A significant chi square indicated that recovery among females is significantly more frequent than among males, as shown by the sharply different sex ratios of persistent vs. recovered stutterers. (2) Is persistence or recovery from stuttering heritable? If recovery appears to be heritable, (a) are recovered and persistent stuttering a unitary disorder where recovered stuttering is a genetically milder form of persistent stuttering; (b) is recovery transmitted independent of stuttering; or (c) are recovered and persistent stuttering independent disorders? Results indicated that persistence or recovery are indeed heritable, and further, that recovery is not a milder form, nor do the two types of stuttering appear to be unrelated, independent disorders. Data are most consistent with the hypothesis that persistence is in part due to an additional genetic factor.Segregation analyses supported these conclusions and provided statistical evidence for both a single major locus and polygenic component for persistent and recovered stuttering.This study was supported by grant #R01-DC00459 from the National Institute of Deafness and Other Communication Disorders, National Institutes of Health, Principal Investigator: Ehud Yairi.Made available in DSpace on 2011-05-07T12:49:38Z (GMT). No. of bitstreams: 2
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Previous issue date: 1996Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding ([email protected]) on 2011-05-07T14:46:21Z
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Structure of blocks with normal defect and abelian p′ inertial quotient
No full textOpen Access via the CUP Agreement Funding Information: The first author is grateful to City, University of London for its hospitality during the research for this paper, and to Ehud Meir for conversations about the proof of Theorem . The second author acknowledges support from EPSRC grant EP/T004592/1.Peer reviewe
Recognition by functional parts
No full textWe present an approach to function-based object recognition that reasons about the functionality of an object's intuitive parts. We extend the popular ``recognition by parts'' shape recognition framework to support ``recognition by functional parts'', by combining a set of functional primitives and their relations with a set of abstract volumetric shape primitives and their relations. Previous approaches have relied on more global object features, often ignoring the problem of object segmentation and thereby restricting themselves to range images of unoccluded scenes. We show how these shape primitives and relations can be easily recovered from superquadric ellipsoids which, in turn, can be recovered from either range or intensity images of occluded scenes. Furthermore, the proposed framework supports both unexpected (bottom-up) object recognition and expected (top-down) object recognition. We demonstrate the approach on a simple domain by recognizing a restricted class of hand-tools from 2-D images.Technical report lcsr-tr-24
Acoustic and physiologic analyses of hyperfunctional voice disorders
No full text"This study investigated the acoustic and physiologic correlates of vocal fatigue in 10 speakers with vocal nodules and 10 normal speakers in a natural environment and during an experimentally induced vocal fatigue speaking task. All subjects were examined by an otolaryngologist for the presence or absence of vocal nodules. Furthermore, experimental subjects' voices were rated as ""abnormal"" while the normal subjects' voices were rated as ""normal"" by three independent listeners.""Acoustic (fundamental frequency, jitter, shimmer and signal-to-noise ratio) and physiologic (closed-to-open ratios of electroglottograph waveforms) measures were obtained for each subject over three consecutive days at three target times: ""morning"" or two hours after waking; ""afternoon"" or seven hours after waking; and ""evening"" or twelve hours after waking. On the fourth consecutive day two hours after waking, subjects read orally for 60 minutes using a loud voice (75-80 dB SPL at 30 cm microphone-to-mouth distance). Every twenty minutes subjects were interrupted to obtain acoustic and electroglottographic data."The results showed no significant differences between the groups regarding a pattern of change in the measures across time in a natural environment. Only fundamental frequency and signal-to-noise ratio varied from morning to evening over the three days for individual subjects in both groups. During the prolonged reading task, both groups tended to increase fundamental frequency from baseline to 60 minutes. Signal-to-noise ratio increased from baseline to 60 minutes in the experimental group, but remained relatively stable across time in the normal group. With this exception, no other differences between the groups were found regarding a pattern of change in the acoustic or physiologic measures.It was interesting that the closed-to-open ratio was the only measure that clearly differentiated the experimental from the control group. Specifically, the experimental subjects demonstrated lower closed-to-open ratios than the control subjects. The lack of significant changes over time in the voices of the two groups, or differences between them, both in a natural and controlled conditions, suggests a need to re-evaluate the traditional assumptions regarding the dynamics of vocal fatigue.Made available in DSpace on 2011-05-07T14:07:45Z (GMT). No. of bitstreams: 2
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Previous issue date: 1991Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding ([email protected]) on 2011-05-07T15:03:15Z
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Descent, fields of invariants, and generic forms via symmetric monoidal categories
No full textThe author was supported by the Danish National Research Foundation (DNRF) through the Centre for Symmetry and Deformation. The author is grateful to Eli Aljadeff, Apostolos Beligiannis, Julien Bichon, Pavel Etingof, Gaston Garcia, Christian Kassel, Bernhard Keller, Henning Krause, Akira Masuoka and Jan Stovicek for guidance and for fruitful discussions.Peer reviewe
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