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In recent years, an increasing number of mutations in what would appear to be 'housekeeping genes' have been identified as having unexpectedly specific defects in multicellular organogenesis. This is also the case for organogenesis in seed plants. Although it is not surprising that loss-of-function mutations in 'housekeeping' genes result in lethality or growth retardation, it is surprising when (1) the mutant phenotype results from the loss of function of a 'housekeeping' gene and (2) the mutant phenotype is specific. In this review, by defining housekeeping genes as those encoding proteins that work in basic metabolic and cellular functions, we discuss unexpected links between housekeeping genes and specific developmental processes. In a surprising number of cases housekeeping genes coding for enzymes or proteins with functions in basic cellular processes such as transcription, post-transcriptional modification, and translation affect plant development.
In aquatic food webs, consumers, such as daphnids and copepods, differ regarding their accumulation of polyunsaturated fatty acids (PUFAs). We tested if the accumulation of PUFAs in a seston size fraction containing different consumers and in Daphnia as a separate consumer is subject to seasonal changes in a large deep lake due to changes in the dietary PUFA supply and specific demands of different consumers. We found that the accumulation of arachidonic acid (ARA) in Daphnia increased from early summer to late summer and autumn. However, ARA requirements of Daphnia appeared to be constant throughout the year, because the accumulation of ARA increased when the dietary ARA supply decreased. In the size fraction 140 m, we found an increased accumulation of docosahexaenoic acid (DHA) during late summer and autumn. These seasonal changes in DHA accumulation were linked to changes in the proportion of copepods in this size fraction, which may have increasingly accumulated DHA for active overwintering. We show that consumer-specific PUFA demands can result in seasonal changes in PUFA accumulation, which may influence the trophic transfer of PUFAs within the food web.
Background: In behavioural tests of sentence comprehension in aphasia, correct and incorrect responses are often randomly distributed. Such a pattern of chance performance is a typical trait of Broca's aphasia, but can be found in other aphasic syndromes as well. Many researchers have argued that chance behaviour is the result of a guessing strategy, which is adopted in the face of a syntactic breakdown in sentence processing. Aims: Capitalising on new evidence from recent studies investigating online sentence comprehension in aphasia using the visual world paradigm, the aim of this paper is to review the concept of chance performance as a reflection of a syntactic impairment in sentence processing and to re-examine the conventional interpretation of chance performance as a guessing behaviour. Main Contribution: Based on a review of recent evidence from visual world paradigm studies, we argue that the assumption of chance performance equalling guessing is not necessarily compatible with actual real-time parsing procedures in people with aphasia. We propose a reinterpretation of the concept of chance performance by assuming that there are two distinct processing mechanisms underlying sentence comprehension in aphasia. Correct responses are always the result of normal-like parsing mechanisms, even in those cases where the overall performance pattern is at chance. Incorrect responses, on the other hand, are the result of intermittent deficiencies of the parser. Hence the random guessing behaviour that persons with aphasia often display does not necessarily reflect a syntactic breakdown in sentence comprehension and a random selection between alternatives. Instead it should be regarded as a result of temporal deficient parsing procedures in otherwise normal-like comprehension routines. Conclusion: Our conclusion is that the consideration of behavioural offline data alone may not be sufficient to interpret a performance in language tests and subsequently draw theoretical conclusions about language impairments. Rather it is important to call on additional data from online studies that look at language processing in real time in order to gain a comprehensive picture about syntactic comprehension abilities of people with aphasia and possible underlying deficits.
The purpose of this study was to investigate the association between variables of lower extremity muscle strength, balance, and mobility assessed under various task conditions.
Twenty-one healthy children (mean age: 9 +/- 1 years) were tested for their isometric and dynamic strength as well as for their steady-state, proactive, and reactive balance and mobility. Balance and mobility tests were conducted under single and dual task conditions.
Significant positive correlations were detected between measures of isometric and dynamic leg muscle strength. Hardly any significant associations were observed between variables of strength and balance/mobility and between measures of steady-state, proactive, and reactive balance. Additionally, no significant correlations were detected between balance/mobility tests performed under single and dual task conditions.
The predominately non-significant correlations between different balance components and mobility imply that balance and mobility performance is task specific. Further, strength and balance/mobility as well as balance under single and dual task conditions seem to be independent of each other and may have to be tested and trained complementarily.
Poststroke spasticity (PSS)-related disability is emerging as a significant health issue for stroke survivors. There is a need for predictors and early identification of PSS in order to minimize complications and maladaptation from spasticity. Reviewing the literature on stroke and upper motor neuron syndrome, spasticity, contracture, and increased muscle tone measured with the Modified Ashworth Scale and the Tone Assessment Scale provided data on the dynamic time course of PSS. Prevalence estimates of PSS were highly variable, ranging from 4% to 42.6%, with the prevalence of disabling spasticity ranging from 2% to 13%. Data on phases of the PSS continuum revealed evidence of PSS in 4% to 27% of those in the early time course (1-4 weeks poststroke), 19% to 26.7% of those in the postacute phase (1-3 months poststroke), and 17% to 42.6% of those in the chronic phase (>3 months poststroke). Data also identified key risk factors associated with the development of spasticity, including lower Barthel Index scores, severe degree of paresis, stroke-related pain, and sensory deficits. Although such indices could be regarded as predictors of PSS and thus enable early identification and treatment, the different measures of PSS used in those studies limit the strength of the findings. To optimize evaluation in the different phases of care, the best possible assessment of PSS would make use of a combination of indicators for clinical impairment, motor performance, activity level, quality of life, and patient-reported outcome measures. Applying these recommended measures, as well as increasing our knowledge of the physiologic predictors of PSS, will enable us to perform clinical and epidemiologic studies that will facilitate identification and early, multimodal treatment.
This article presents the results of a study on the interpretation and acceptance of adjectival resultatives of German children between 6 and 9 years of age and adults. These results brought to light significant differences, due to age, in the interpretation and acceptance of these resultatives, that is to say, sentences with an adjective in the final position. The youngest participants were prone to accept ungrammatical sentences by assigning a resultative meaning. The ungrammaticality of the sentences in question was not due to semantic inconsistencies but to violations of the selectional properties of verbs, as for instance in *die Kinder erschrecken die Katze angstlich 'the children frighten the cat scared'. In contrast, the adults rejected or amended those sentences. The conclusion is (a) that the children seemed to rely on the sentence structure as a primary cue to compute the meaning of an utterance and (b) that, in contrast with adults, the youngest children in particular had not yet learned the relevant semantic properties of verbs that determine the selectional restrictions and thus the syntactic options of verbs. This means that differences in interpretation and acceptance of sentences are due to differences in knowledge of semantic verb properties between adults and children. The relevant semantic knowledge increases in gradual stages during language acquisition.
In this article, it will be argued that the concept of functional layering - an extension of Hopper's (1991) concept of layering - can be fruitfully applied to understand the mechanisms behind the sometimes large and messy looking synchronic picture of diverse meanings which one and the same construction can fulfill at a particular point in time. The concept will be used to account for the meaning spectrum of the present-day English progressive, which, it will be argued, no monosemic approach to date can account for. Taking a look at the diachrony of the construction will help to reveal that the various "exceptions" found in the use of the progressive can be understood as reflections of different stages in its development. Older, less grammaticalized or less well-defined usage patterns thus often survive in certain restricted niches next to the newer, more grammaticalized or more clear-cut functions, representing different diachronic layers. In addition to this diachronic motivation for synchronic meaning variety, the article will also address the crucial question of how a present-day hearer of a progressive form is able to decode the specific meaning intended by the speaker based on contextual clues. The article ends with some suggestions for further applications of the concept of functional layering.
Nowadays, an increasing amount of seismic data is collected by daily observatory routines. The basic step for successfully analyzing those data is the correct detection of various event types. However, the visually scanning process is a time-consuming task. Applying standard techniques for detection like the STA/LTAtrigger still requires the manual control for classification. Here, we present a useful alternative. The incoming data stream is scanned automatically for events of interest. A stochastic classifier, called hidden Markov model, is learned for each class of interest enabling the recognition of highly variable waveforms. In contrast to other automatic techniques as neural networks or support vector machines the algorithm allows to start the classification from scratch as soon as interesting events are identified. Neither the tedious process of collecting training samples nor a time-consuming configuration of the classifier is required. An approach originally introduced for the volcanic task force action allows to learn classifier properties from a single waveform example and some hours of background recording. Besides a reduction of required workload this also enables to detect very rare events. Especially the latter feature provides a milestone point for the use of seismic devices in alpine warning systems. Furthermore, the system offers the opportunity to flag new signal classes that have not been defined before. We demonstrate the application of the classification system using a data set from the Swiss Seismological Survey achieving very high recognition rates. In detail we document all refinements of the classifier providing a step-by-step guide for the fast set up of a well-working classification system.
The knowledge of the local soil structure is important for the assessment of seismic hazards. A widespread, but time-consuming technique to retrieve the parameters of the local underground is the drilling of boreholes. Another way to obtain the shear wave velocity profile at a given location is the inversion of surface wave dispersion curves. To ensure a good resolution for both superficial and deeper layers, the used dispersion curves need to cover a wide frequency range. This wide frequency range can be obtained using several arrays of seismic sensors or a single array comprising a large number of sensors. Consequently, these measurements are time-consuming. A simpler alternative is provided by the use of the ellipticity of Rayleigh waves. The frequency dependence of the ellipticity is tightly linked to the shear wave velocity profile. Furthermore, it can be measured using a single seismic sensor. As soil structures obtained by scaling of a given model exhibit the same ellipticity curve, any inversion of the ellipticity curve alone will be ambiguous. Therefore, additional measurements which fix the absolute value of the shear wave velocity profile at some points have to be included in the inversion process. Small-scale spatial autocorrelation measurements or MASW measurements can provide the needed data. Using a theoretical soil structure, we show which parts of the ellipticity curve have to be included in the inversion process to get a reliable result and which parts can be omitted. Furthermore, the use of autocorrelation or high-frequency dispersion curves will be highlighted. The resulting guidelines for inversions including ellipticity data are then applied to real data measurements collected at 14 different sites during the European NERIES project. It is found that the results are in good agreement with dispersion curve measurements. Furthermore, the method can help in identifying the mode of Rayleigh waves in dispersion curve measurements.
Cell-free protein synthesis (CFPS) is a valuable method for the fast expression of difficult-to-express proteins as well as posttranslationally modified proteins. Since cell-free systems circumvent possible cytotoxic effects caused by protein overexpression in living cells, they significantly enlarge the scale and variety of proteins that can be characterized. We demonstrate the high potential of eukaryotic CFPS to express various types of membrane proteins covering a broad range of structurally and functionally diverse proteins. Our eukaryotic cell-free translation systems are capable to provide high molecular weight membrane proteins, fluorescent-labeled membrane proteins, as well as posttranslationally modified proteins for further downstream analysis.