Temporal Modification Research Articles

Isolation, characterization and heterologous expression of a novel chitosanase from Janthinobacterium sp. strain 4239

BackgroundChitosanases (EC 3.2.1.132) hydrolyze the polysaccharide chitosan, which is composed of partially acetylated β-(1,4)-linked glucosamine residues. In nature, chitosanases are produced by a number of Gram-positive and Gram-negative bacteria, as well as by fungi, probably with the primary role of degrading chitosan from fungal and yeast cell walls for carbon metabolism. Chitosanases may also be utilized in eukaryotic cell manipulation for intracellular delivery of molecules formulated with chitosan as well as for transformation of filamentous fungi by temporal modification of the cell wall structures.However, the chitosanases used so far in transformation and transfection experiments show optimal activity at high temperature, which is incompatible with most transfection and transformation protocols. Thus, there is a need for chitosanases, which display activity at lower temperatures.ResultsThis paper describes the isolation of a chitosanase-producing, cold-active bacterium affiliated to the genus Janthinobacterium. The 876 bp chitosanase gene from the Janthinobacterium strain was isolated and characterized. The chitosanase was related to the Glycosyl Hydrolase family 46 chitosanases with Streptomyces chitosanase as the closest related (64% amino acid sequence identity). The chitosanase was expressed recombinantly as a periplasmic enzyme in Escherichia coli in amounts about 500 fold greater than in the native Janthinobacterium strain. Determination of temperature and pH optimum showed that the native and the recombinant chitosanase have maximal activity at pH 5-7 and at 45°C, but with 30-70% of the maximum activity at 10°C and 30°C, respectively.ConclusionsA novel chitosanase enzyme and its corresponding gene was isolated from Janthinobacterium and produced recombinantly in E. coli as a periplasmic enzyme. The Janthinobacterium chitosanase displayed reasonable activity at 10°C to 30°C, temperatures that are preferred in transfection and transformation experiments.

BK Channels Control Cerebellar Purkinje and Golgi Cell Rhythmicity In Vivo

Calcium signaling plays a central role in normal CNS functioning and dysfunction. As cerebellar Purkinje cells express the major regulatory elements of calcium control and represent the sole integrative output of the cerebellar cortex, changes in neural activity- and calcium-mediated membrane properties of these cells are expected to provide important insights into both intrinsic and network physiology of the cerebellum. We studied the electrophysiological behavior of Purkinje cells in genetically engineered alert mice that do not express BK calcium-activated potassium channels and in wild-type mice with pharmacological BK inactivation. We confirmed BK expression in Purkinje cells and also demonstrated it in Golgi cells. We demonstrated that either genetic or pharmacological BK inactivation leads to ataxia and to the emergence of a beta oscillatory field potential in the cerebellar cortex. This oscillation is correlated with enhanced rhythmicity and synchronicity of both Purkinje and Golgi cells. We hypothesize that the temporal coding modification of the spike firing of both Purkinje and Golgi cells leads to the pharmacologically or genetically induced ataxia.

Validation of Temporal Optimization Effects for a Single Fraction of Radiation In Vitro

To experimentally validate how temporal modification of the applied dose pattern within a single fraction of radiation therapy affects cell survival. Using the linear-quadratic model, we have previously demonstrated that the greatest difference in cell survival results from comparing a temporal dose pattern delivering the highest doses during the middle of a fraction and the lowest at the beginning and end ("Triangle") to one with the lowest doses at the middle and the highest at the beginning and end ("V-shaped"). Also, these differences would be greatest in situations with low alpha/beta and large dose/fraction and fraction length. Two low (WiDr, PC-3) and one high (SQ-20B) alpha/beta cell lines were irradiated in six-well plates with 900 cGy over 20 min (900 cGy/20 min), one each with a Triangle and V-shaped dose pattern. WiDr cells were subjected to the same experiments with first 180 cGy/20 min, then 900 cGy/5 min. Cell survival was assessed using the clonogenic assay. At 900 cGy/20 min, irradiation with a V-shaped pattern resulted in an increased survival compared with use of a Triangle pattern of 21.2% for WiDr (p < 0.01), 18.6% for PC-3 (p < 0.025), and 4.7% for SQ-20B cells (p > 0.05). For WiDr cells at 180 cGy/20 min, this increase reduced to 2.7% (p > 0.05) and to -0.8% (p > 0.05) at 900 cGy/5 min. These results verify the assertions of the modeling study in vitro, and imply that the temporal pattern of applied dose should be considered in treatment planning and delivery.

Temporal modification in Greek adverbial clauses: The role of aspect and negation

The aim of this paper is to provide a formal account of the differences between adverbial clauses introduced by the Greek temporal connectives kathos, eno and afu. Based on Haegeman's (2003, this issue) criteria for distinguishing between central and peripheral clauses, we examine the ‘external’ and ‘internal’ syntax of Greek adverbials introduced by these connectives. Although Haegeman's proposal aims to cover not only English but also cross-linguistic properties of central vs. peripheral clauses, we would like to argue that there are certain language-specific criteria, namely aspect and negation, which could be used as additional support for the structural distinction proposed and which call for some modifications of the structural differences suggested for English adverbials. The Greek connectives are shown to be aspectually dependent in the sense that they are specified for [boundedness] as part of their lexical entry. This property affects their structural position in central vs. peripheral adverbials, on one hand, and the possibilities of temporal anchoring onto the matrix clause, on the other. Finally, the language-specific criteria discussed, namely aspect and negation, are tested through an interpretation task with native speakers of Greek in order to establish the preference for the temporal over the non-temporal readings when aspect and negation are controlled for.

Invited Commentary: Heterogeneity of Particulate Matter Health Risks

Ambient particulate matter varies in composition and toxicity; therefore, some heterogeneity in risk per unit mass can be anticipated. In this issue of the Journal (Am J Epidemiol 2007;166:880-888), Dominici et al. explore temporal and spatial effect modification of particulate matter potency with the goal of gaining insights about how differences in the mixture may affect toxicity of the particulate matter, and they propose that it may be a useful tool in assessing the net impact of regulatory activity. Their approach is fresh and creative and yields provocative results. Such assessments will, of course, be constrained by limited power to detect the expected small degree of effect modification, as well as an abundance of possible explanations for observed differences in risk per unit mass. The utility for accountability assessment is further limited because regulatory actions impacting particulate matter levels do not necessarily target the most toxic species within the mixture and may confer benefits by reducing population exposure to particles and components of lesser toxicity. Used cautiously, however, this new methodology may provide a complementary approach to more direct assessments in shedding light on the characteristics of ambient particulate matter predictive of health effects.

Modulation of biting procedures induced by the sensory evaluation of cheese hardness with different definitions

This study seeks to clarify the bite process in individuals who assess cheese hardness to confirm the relationships among hardness definitions, their causative bite procedures, targeted intra-oral mechanical events, and judgment. Subjects were required to bite and evaluate samples using two different definitions of hardness. We measured an intra-oral bite time–force profile using a tactile pressure-measurement system with a sheet sensor unobtrusively inserted into the subject's mouth along with a sample. The first bite profile was an exploratory procedure adjusted to optimize perception of the designated textural attribute. From the temporal modification of the bite profile, we could estimate the bite parameter that was targeted as the sensory information for a particular texture attribute. We examined inter-definition and inter-subject variations in the relationship between hardness judgment and its sensory source estimated from the bite procedure. We demonstrated that the bite measurement could elucidate both the bite procedures and sensory information for hardness evaluation. Different definitions induced different bite procedures that resulted in a change in the sensory signal. The definition also affected inter-subject variability in bite procedures and sensory–judgment correspondence.

SU‐FF‐T‐02: In Vitro Validation of Temporal Optimization Effects On Cell Survival for a Single Fraction of Radiation

Purpose: To experimentally validate how temporal modification of the applied dose pattern within a single fraction of radiation therapy affects cell survival. Method and Materials: The linear quadratic (LQ) repair‐time model predicts that, for a single fraction of dose, the degree of cell kill is dependent on the pattern of dose applied over a period of irradiation. Previously, we demonstrated that: (1) maximum cell kill is achieved using a “triangular” temporal dose pattern (delivering the highest doses during the middle of a fraction and the lowest at the beginning and end), and (2) minimum cell kill is achieved with a “V‐shaped” pattern (delivering the lowest doses at the middle of a fraction and the highest at the beginning and end). Furthermore, the model also predicted that cells with low α/β values will have a larger difference in survival based on the applied pattern of dose. Two cells lines with low α/β values (PC‐3, WiDr) and one with a high α/β value (SQ‐20b) were chosen for this study. For each cell line, one group of cells in a six‐well plate received 9 Gy in a triangular dose pattern, and the same dose was delivered to a second plate using a V‐shaped pattern. The delivery time for each dose pattern was 20 min. Cell survival was assessed using a clonogenic assay. Results: For the SQ‐20b cells, irradiation with both dose patterns resulted in only a 4.5% relative difference in cell survival (p&gt;0.25). However, the triangle and V‐shaped patterns resulted in relative cell survival differences of 15.2% and 18.6% for both the PC‐3 (p&lt;0.025) and WiDr (p&lt;0.01) cell lines, respectively. Conclusion: These results verify the assertions of the modeling study in vitro, and imply that the temporal pattern of applied dose is another variable to be considered in treatment planning and delivery.

Electrostatic coherent structures generation by local heating in a collisionless plasma

Abstract We propose a new mechanism for the generation of electrostatic coherent structures and Langmuir fluctuations in a stratified plasma. The model is base on open boundary 1D Vlasov simulations where heated electrons are injected by applying a temporal continuous periodic modification of the width of the electron distribution function at one boundary of the simulation box. To our knowledge, that is the first time that a “localized heating” mechanism is studied as a driver for the development of bi(multi)polar electric field with their associated electron density holes and vortices in the phase space. After the development of many electrostatic coherent structures, the injected fast particles are free to move along their ballistic limit, while electrons moving at nearly, or less than, the thermal speed are diffused in phase space by the local fields.

On the generation and perception characteristics of Japanese timing control

We have been studying temporal characteristics of Japanese for decades. Not only acoustic measurements but also perceptual studies on temporal modification have revealed the control principles lying behind manifestation of segmental duration characteristics. This talk tries to introduce familiar generation principles such as ‘‘mora‐timing’’ and phrasal tempo reset from the viewpoint of humans temporal organization through the understanding of duration statistics. Moreover, by showing perceptual characteristics including sentential factors, we would like to propose how linguistic units relate to temporal perception and what kind of information form can be considered in temporal cognition process. Some of our recent efforts will also be presented to investigate language‐dependent temporal characteristics by observing non‐native learners temporal control characteristics. We really expect that we will be able to have a better picture of generation and perception mechanism through the cross check of their characteristic differences between natives and non‐natives. [Work supported by Waseda Univ. RISE research project of ‘‘Analysis and modeling of human mechanism in speech and language processing’’ and Grant‐in‐Aid for and Scientific Research A‐2, No. 16200016 of JSPS.]

The Blindness Hypothesis and Individual Level Predicates

No abstract.

Plurality and Temporal Modification

A semantics with plural entitles and plural times accounts for cumulative relations between plural arguments and temporal expressions. The semantics equips nominal, verbal and sentential meanings with temporal context variables and treats temporal modifiers as temporal generalized quantifiers; cumulative conjunction, however, takes place at types lower than generalized quantifiers. The mediation of temporal context variables allows cumulative relations to percolate between an argument in a main clause and one in a temporal clause, in apparent violation of locality restrictions. Plural times form a semilattice structure imposed on the set of intervals; no interaction is observed between this and the internal temporal structure of intervals.

The effects of temporal modification of second speech signals on stuttering inhibition at two speech rates in adults

The recovery of ‘gestural’ speech information via the engagement of mirror neurons has been suggested to be the key agent in stuttering inhibition during the presentation of exogenous second speech signals. Based on this hypothesis, we expect the amount of stuttering inhibition to depend on the ease of recovery of exogenous speech gestures. To examine this possibility, linguistically non-congruent second speech signals were temporally compressed and expanded in two experiments. In Experiment 1, 12 participants who stutter read passages aloud at normal and fast speech rates while listening to second speech signals that were 0, 40, 80% compressed, and 40 and 80% expanded. Except for the 80% compressed speech signal, all other stimuli induced significant stuttering inhibition relative to the control condition. The 80% compressed speech signal was the first exogenously presented speech signal that failed to significantly reduce stuttering frequency by 60–70% that has been the case in our research over the years. It was hypothesized that at a compression ratio of 80%, exogenous speech signals generated too many gestures per unit time to allow for adequate gestural recovery via mirror neurons. However, considering that 80% compressed signal was also highly unintelligible, a second experiment was conducted to further examine whether the effects of temporal compression on stuttering inhibition are mediated by speech intelligibility. In Experiment 2, 10 participants who stutter read passages at a normal rate while listening to linguistically non-congruent second speech signals that were compressed by 0, 20, 40, 60, and 80%. Results revealed that 0 and 20% compressed speech signals induced approximately 52% stuttering inhibition. In contrast, compression ratios of 40% and beyond induced only 27% stuttering inhibition although 40 and 60% compressed signals were perceptually intelligible. Our findings suggest that recovery of gestural information is affected by temporal compression before intelligibility starts to decrease.

Temporal correlation modification by microbubbles injection in a channel flow

In an effort to achieve a better understanding of the drag reduction mechanism by microbubbles injection, the structure of flow turbulence in a water channel with microbubbles is studied using particle image velocimetry technique (PIV) at Re h = 5128. Full field of the two-dimensional velocity components (streamwise and normal) within a location close to the wall was measured. The effects of several values of local void fraction upon the drag reduction are investigated.

Functional differences between vowel onsets and offsets in temporal perception of speech: local-change detection and speaking-rate discrimination.

To provide a perceptual framework for the objective evaluation of durational rules in speech synthesis, two experiments were conducted to investigate the differences between vowel (V) onsets and V-offsets in their functions of marking the perceived temporal structure of speech. The first experiment measured the detectability of temporal modifications given in four-mora (CVCVCVCV) Japanese words. In the V-onset condition, the inter-onset intervals of vowels were uniformly changed (either expanded or reduced) while their inter-offset intervals were preserved. In the V-offset condition, this was reversed. These manipulations did not change the duration of the entire word. Each of the modified words was paired with its unmodified counterpart, and the pair was given to listeners, who were asked to rate the difference between the paired words. The results show that there were no significant differences in the listeners' abilities to detect the temporal modification between the V-onset and V-offset conditions. In the second experiment, the listeners were asked to estimate the differences they perceived in speaking rates for the same stimulus set as that of the first experiment. Interestingly, the results show a clear difference in the listeners' performance between the V-onset and V-offset conditions. Specifically, changing the V-onset intervals changed the perceived speaking rates, which showed a linear relation (r = -0.9) despite the fact that the duration of the entire word remained unchanged. In contrast, modifying the V-offset intervals produced no clear relation with the perceived speaking rates. The second experiment also showed that the listeners performed well in speaking rate discrimination (3.5%-5% in the change ratio). These results are discussed in relation to the differences in the listeners' temporal processing range (local or global) between the two experiments.

Numerical simulation of the fouling process

Fouling of heat transfer surfaces causes serious technical and economic problems in industry. The goal of this work is to simulate the aforementioned fouling process using the CFD code FLUENT. The obtained numerical results assist in designing and running heat exchangers. Based on models for the calculation of deposition and removal mass rates [S. Krause, Internat. Chem. Engrg. 33 (1993)], the crystallization fouling of calcium sulfate on flat heat transfer surfaces was simulated. The induction period, which occurs with almost all fouling processes, was therefore not considered. The simulation of real crystal growth requires a continuous variation of the geometric flow model and therefore considerable computational effort. For that reason fictitious crystal growth was simulated instead. This numerical simplification enabled an unsteady simulation to be obtained, of the fouling process and a realistic description of the temporal modification of both the flow and temperature field due to the continuous crystal growth. Based on experimental results of Hirsch [M. Bohnet et al., in: T.R. Bott et al. (Eds.), Understanding Heat Exchanger Fouling and its Mitigation, United Engineering Foundation and Begell House, New York, 1997, pp. 201–208], a model was developed which enables the calculation of the density of the fouling layer not only as a function of the local position within the fouling layer, but also as a function of the time-dependent total thickness of the fouling layer. In addition a model was developed, that enables a realistic distribution of the heat flux along the heat transfer surface during the simulation. Both models provide a more exact description of the complicated fouling process. Results of the numerical simulation are the prediction of the fouling resistance as a function of time and the calculation of the temperature distribution within the fouling layer. In view of the complexity of the fouling process during the incrustation of heat transfer surfaces and the fact that not all influences from the used models could be considered the agreement between calculated and experimentally obtained data is satisfactory.

Acceptability for temporal modification of single vowel segments in isolated words.

Few perceptual studies of the temporal aspects of speech have investigated the influence of changes in segmental durations in terms of acceptability. Aiming to contribute to the assessment of rules for assigning segmental durations in speech synthesis, the current study measured the perceptual acceptability of changes in the segmental duration of vowels as a function of the segment attributes or context, such as base duration, temporal position in a word, vowel quality, and voicing of the following segment. Seven listeners estimated the acceptability of word stimuli in which one of the vowels was subjected to a temporal modification from -50 ms (for shortening) to +50 ms (for lengthening) in 5-ms steps. The temporal modification was applied to vowel segments in 70 word contexts; their durations ranged from 35-145 ms, the mora position in the word was first or third, the vowel quality was /a/ or /i/, and the following segment was a voiced or an unvoiced consonant. The experimental results showed that the listeners' acceptable range of durational modification was narrower for vowels in the first moraic position in the word than for those in the third moraic position. The acceptable range was also narrower for the vowel /a/ than for the vowel /i/, and similarly narrower for vowels followed by unvoiced consonants than for those followed by voiced consonants. The vowel that fell into the least vulnerable class (the third /i/, followed by a voiced consonant) required 140% of the modification of that which fell into the most vulnerable class (the first /a/, followed by an unvoiced consonant) to yield the same acceptability decrement. In contrast, the effect of the original vowel duration on the acceptability of temporal modifications was not significant despite its wide variation (35-145 ms).

Aspectual Shift as Type Coercion

The phenomenon of aspectual shift has been discussed by several people over the last ten years using an analogy with type coercion in programming languages. This paper tries to take the analogy literally and to spell out the details for an analysis of some common kinds of aspectual shift in English under the influence of some types of temporal modification. A model‐theoretic basis for this kind of type coercion is supplied, and an illustrative fragment is worked out.

Acceptability for temporal modification of consecutive segments in isolated words.

Perceptual sensitivity to temporal modification in two consecutive speech segments was measured in word contexts to explore the following two questions: (1) whether there is an interaction between multiple segmental durations, and (2) what aspect of the stimulus context determines the perceptually salient temporal markers? Experiment 1 obtained acceptability ratings for words with temporal modifications. The results showed that the compensatory change in duration of a vowel (V) and its adjacent consonant (C) is not perceptually so salient as expected for the simultaneous modifications in the two segments. This finding suggests the presence of a time perception range wider than a single segment (V or C). The results of experiment 1 also showed that rating scores for compensatory modification between V and C do not depend on the temporal order of modified pairs (VC or CV), but rather on the loudness difference between V and C; the acceptability decreased when the loudness difference between V and C became high. This suggests that perceptually salient markers locate around major jumps in loudness. The second finding, the dependence on the loudness jump, was replicated in experiment 2, which utilized a detection task for temporal modifications on nonspeech stimuli modeling the time-loudness features of the speech stimuli. Experiment 3 further investigated the influence of the temporal order of V and C by utilizing the detection task for the speech stimuli instead of the acceptability ratings.

A model of nematode dynamics in the Westerschelde Estuary

We developed a time dynamic model to investigate the temporal dynamics of nematode community in the brackish zone of the Westerschelde Estuary. The biomass of four nematode feeding groups observed from March 1991 to February 1992 is used to calibrate the model. Using environmental data as the input, the model predicts the temporal modification and interrelation of four nematode feeding groups. Nematodes achieve a dominant position in the community because of their lower loss rate (in respiration, excretion and natural death). Predators which are deposit-feeding macrobenthos control the variations of dominant nematodes, such as omnivores and non-selective deposit feeders. Food availability causes modification only for rare nematodes such as epigrowth feeders and selective deposit feeders. Temperature is a factor affecting both predation death and a loss including respiration, excretion and natural death. Overall, the modification of nematode community by food availability is much lower than by predator. The macrobenthos in the Westerschelde Estuary decrease from upstream to the estuarine mouth. The stability and standing stock of nematode population follow the opposite gradient of their predators. They increase from upstream to the estuarine mouth.

Time-based operators for relational algebra query languages

We present a new approach for historical relational algebra languages based upon generalized logic for Boolean and comparison operators and a temporal modification of the standard relational algebra operators. Historical versions of standard (snapshot) relational algebra operators based upon this generalized logic are presented. The temporal modification employs a logic that operates on sets of value/time-interval pairs and which can be applied to snapshot as well as historical databases. Our emphasis is that the generalized operators can be used to enrich existing historical query languages and to provide an easier and more natural time-based interface. Using the generalized operators, users can express their queries more naturally, succinctly and elegantly. Examples are presented which illustrate that the modified operators offer a good degree of flexibility in expressing different temporal requirements.