228,694 research outputs found
Zinc finger recombinases with adaptable DNA sequence specificity
No full textSite-specific recombinases have become essential tools in genetics and molecular biology for the precise excision or integration of DNA sequences. However, their utility is currently limited to circumstances where the sites recognized by the recombinase enzyme have been introduced into the DNA being manipulated, or natural 'pseudosites' are already present. Many new applications would become feasible if recombinase activity could be targeted to chosen sequences in natural genomic DNA. Here we demonstrate efficient site-specific recombination at several sequences taken from a 1.9 kilobasepair locus of biotechnological interest (in the bovine beta-casein gene), mediated by zinc finger recombinases (ZFRs), chimaeric enzymes with linked zinc finger (DNA recognition) and recombinase (catalytic) domains. In the "Z-sites" tested here, 22 bp casein gene sequences are flanked by 9 bp motifs recognized by zinc finger domains. Asymmetric Z-sites were recombined by the concomitant action of two ZFRs with different zinc finger DNA-binding specificities, and could be recombined with a heterologous site in the presence of a third recombinase. Our results show that engineered ZFRs may be designed to promote site-specific recombination at many natural DNA sequence
A finger mechanism for adaptive end effectors
No full textThis paper presents design and analysis of a rigid link finger, which may be suitable for a number of adaptive end effectors. The design has evolved from an industrial need for a tele-operated system to be used in nuclear environments. The end effector is designed to assist repair work in nuclear reactors during retrieval operation, particularly for the purpose of grasping objects of various shape, size and mass. The work is based on the University of Southampton's Whole Arm Manipulator, which has a special design consideration for safety and flexibility. The paper discusses kinematic issues associated with the finger design, and to the end of the paper specifies the limits of finger operating parameters for implementing control law
Disruption of the developmental programme of Trypanosoma brucei by genetic ablation of TbZFP1, a differentiation-enriched CCCH protein
No full textThe regulation of differentiation is particularly important in microbial eukaryotes that inhabit multiple environments. The parasite Trypanosoma brucei is an extreme example of this, requiring exquisite gene regulation during transmission from mammals to the tsetse fly vector. Unusually, trypanosomes rely almost exclusively on post-transcriptional mechanisms for regulated gene expression. Hence, RNA binding proteins are potentially of great significance in controlling stage-regulated processes. We have previously identified TbZFP1 as a trypanosome molecule transiently enriched during differentiation to tsetse midgut procyclic forms. This small protein (101 amino acids) contains the unusual CCCH zinc finger, an RNA binding motif. Here, we show that genetic ablation of TbZFP1 compromises repositioning of the mitochondrial genome, a specific event in the strictly regulated differentiation programme. Despite this, other events that occur both before and after this remain intact. Significantly, this phenotype correlates with the TbZFP1 expression profile during differentiation. This is the first genetic disruption of a developmental regulator in T. brucei. It demonstrates that programmed events in parasite development can be uncoupled at the molecular level. It also further supports the importance of CCCH proteins in key aspects of trypanosome cell function
Data on risk preferences and risk literacy for a sample of German agricultural sciences students
No full textThe data presented here contains information on risk preferences, risk literacy and personal characteristics collected from 244 German agricultural sciences students in an online survey in 2015. Two different risk preference elicitation methods have been used. First, we used an iterative multiple price list (iMPL). Second, a simple self-assessment of risk preferences was used. Moreover, we used two different frames of the iMPL (general and context specific). Inconsistent behavior within the iMPL has been documented. Finally, the dataset includes information on the participants’ risk literacy (using the Berlin Numeracy test), gender, optimism, involvement with agriculture age and mothers’ education. The data is related to the paper: Meraner M, Musshoff O, Finger R. Using involvement to reduce inconsistencies in risk preference elicitation. Journal of Behavioral and Experimental Economics. 2018 73:22–33
Vibration-induced white finger in dockyard employees
No full textVibration-induced white finger (VWF) is a vascular condition associated with occupational exposure to hand-transmitted vibration. The fingers are prone to intermittent blanching attacks which may be triggered by cold conditions and are usually accompanied by numbness and tingling or pain. VWF has been associated with the use of various tools and processes, among which are the percussive and rotary metal-working tools used in ship repair work. This thesis describes a study of dose-effect relationships for VWF in dockyard employees.A review of the literature revealed more than 40 epidemiological studies of VWF in workers using hand-held metal-working tools. Measurements of tool vibration have also been reported, but few researchers have combined epidemiological studies of VWF with measurements of the vibration exposures Involved. Some dose-effect relationships have been suggested and current standards contain tentative dose effect guidance. Some recent authors have suggested that the frequency weighting and time-dependencies assumed In current standards are inadequate.Methods for the measurement of hand-transmitted vibration were assessed. The vibration characteristics of sixteen pneumatic tools commonly used in dockyard work were measured in the laboratory. Repeated measurements were made In three axes at each hand position and analysis included the computation of narrow-band spectra, acceleration magnitudes in octave bands and overall frequency-weighted and unweighted acceleration magnitudes.A survey of vibration-exposed employees in a dockyard was conducted by questionnaire. Information related to symptoms of VWF, and the history of use of vibrating tools was obtained from each individual. The severity of blanching in each affected individual was recorded using a scoring system.The severity and prevalence of symptoms were related to various measures of vibration 'dose' (i.e. combinations of measured vibration magnitudes and reported exposure times) by logistic regression and survival analysis. A highly significant relationship between VWF severity and exposure time was demonstrated. However, the use of frequency-weighted acceleration in dose calculations reduced the goodness of fit, while unweighted acceleration gave a small improvement in some cases. This suggests that higher frequencies in the range 6.3 Hz to 1250 Hz are of greater Importance than current standards imply. The effect of vibration magnitude was found to be small compared with that of exposure time and no clear effect of vibration direction or vibration frequency was demonstrated.No evidence was found for a time-dependency of the form assumed in current standards. It is possible that the risk of VWF may not be directly related to the vibration magnitude, but that a 'threshold' magnitude exists, below which the hazard is small and above which it is proportional to a function of the exposure time. Further Investigation of this hypothesis is recommended
Cut-based abduction
No full textIn this paper we explore a generalization of traditional abduction which as simultaneously perform two different tasks: (i) given an unprovable sequent Gamma proves G, find a sentence II such that Gamma, II proves G is provable (hypothesis generation); (ii) given a provable sequent Gamma proves G, find a sentence II such that Gamma proves II and the proof of Gamma, II proves G is simpler than the proof of Gamma proves G (lemma generation). We argue that the two tasks should not be distinguished, and present a general procedure for finding suitable hypotheses or lemmas. When the original sequent is provable, the abduced formula can be seen as a cut formula with respect to Gentzen's sequent calculus, so the abduction method is cut-based. Our method is based on the tablean-like system KE and we argue for its advantages over existing adduction methods based on traditional Smullyan-style Tableaux
The Determination of Finger Flexor Critical Force in Rock Climbers
No full textPurpose: To determine if the mathematical model used for the estimation of critical force (CF) and the energy store component W’ is applicable to intermittent isometric muscle actions of the finger flexors of rock climbers, using a multi-session test. As a secondary aim, the agreement of estimates of CF and W’ from a single-session test were also determined. The CF was defined as the slope coefficient and W’ the intercept of the linear relationship between total “isometric work” (Wlim) and time to exhaustion (Tlim). Methods: Subjects performed three (separated by either 20 m or >24 h) tests to failure using intermittent isometric finger flexor contractions at 45, 60 and 80% of their maximum voluntary contraction (MVC). Results: Force plotted against Tlim displayed a hyperbolic relationship, correlation coefficients of the parameter estimates from the work–time CF model were consistently very high (R2 > 0.94). Climbers mean CF was 425.7 ± 82.8 N (41.0 ± 6.2% MVC) and W’ 30882 ± 11820 N·s. Good agreement was found between the single and multi-session protocol for CF (ICC(3,1) = 0.900, 95% Confidence Interval [CI95%] 0.616 – 0.979), but not for W’ (ICC(3,1) = 0.768, CI95% 0.190 – 0.949). Conclusions: The results demonstrated the sensitivity of a simple test for the determination of CF and W’, using equipment readily available in most climbing gyms. While further work is still necessary, the test of CF described is of value for understanding exercise tolerance and determine optimal training prescription to monitor improvements the performance of the finger flexors
Risks of occupational exposures to hand-transmitted vibration: VIBRISKS
No full textVIBRISKS seeks to improve understanding of the risk of injury from hand-transmitted vibration and whole-body vibration by means of epidemiological studies supported by fundamental laboratory
research. VIBRISKS is a consortium of six partners from six European countries (France, Germany, Italy, Sweden, The Netherlands, UK). The four-year research project, which commenced in 2003, involves three work packages devoted to hand-transmitted vibration and three work packages devoted to whole-body vibration. This paper summarizes the hand-transmitted vibration research. Work package 1 defines methods to be used in studies of disorders caused by hand-transmitted
vibration in work package 2 and integrates the results of the epidemiological studies in work package 2 with the results of experimental and modeling studies in WP3 so as to define procedures that can be applied by occupational health workers for minimizing risk, screening exposed individuals and managing individuals with symptoms. Work package 2 involves longitudinal studies in workers
exposed to hand-transmitted vibration. Work package 3 involves experimental studies of the acute effects of hand-transmitted vibration on vascular and neurological function and the development of a finite element model of the biodynamic responses of the finger to vibration and force
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