4,866 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
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
Increased enslaving in elderly is associated with changes in neural control of the extrinsic finger muscles
No full textAging has consequences for hand motor control, among others affecting finger force enslaving during static pressing tasks. The aim of this study was to assess whether the extent of finger force enslaving changes with aging during a task that involves both static and dynamic phases. Ten right-handed young (22–30 years) and ten elderly subjects (67–79 years) were instructed to first exert a constant force (static phase) and then flex their index finger while counteracting constant resistance forces orthogonal to their fingertips (dynamic phase). The other fingers (non-instructed) were held in extension. EMG activities of the flexor digitorum superficialis (FDS) and extensor digitorum (ED) muscles in the regions corresponding to the index, middle and ring fingers together with their forces and position of index finger were measured. In both elderly and young, forces exerted by the non-instructed fingers increased (around 0.6 N for both young and elderly) during isotonic flexion of the index finger, but with a different delay of on average 100 ± 72 ms in elderly and 334 ± 101 ms in young subjects. Results also suggest different responses in activity of FDS and ED muscle regions of the non-instructed fingers to index finger flexion between elderly and young subjects. The enslaving effect was significantly higher in elderly than in young subjects both in the static (12% more) and dynamic (14% more) phases. These differences in enslaving can at least partly be explained by changes in neuromuscular control.Biomechatronics & Human-Machine Contro
Relation between vibrotactile perception thresholds and reductions in finger blood flow induced by vibration of the hand at frequencies in the range 8–250 Hz
No full textPurpose: this study investigated how the vasoconstriction induced by vibration depends on the frequency of vibration when the vibration magnitude is defined by individual thresholds for perceiving vibration [i.e. sensation levels (SL)].Methods: fourteen healthy subjects attended the laboratory on seven occasions: for six vibration frequencies (8, 16, 31.5, 63, 125, or 250 Hz) and a static control condition. Finger blood flow (FBF) was measured in the middle fingers of both hands at 30-second intervals during five successive periods: (i) no force or vibration, (ii) 2-N force, no vibration, (iii) 2-N force, vibration, (iv) 2-N force, no vibration, (v) no force or vibration. During period (iii), vibration was applied to the right thenar eminence via a 6-mm diameter probe during ten successive 3-min periods as the vibration magnitude increased in ten steps (?10 to +40 dB SL).Results: with vibration at 63, 125, and 250 Hz, there was vasoconstriction on both hands when the vibration magnitude reached 10 dB SL. With vibration at 8, 16, and 31.5 Hz, there was no significant vasoconstriction until the vibration reached 25 dB SL. At all frequencies, there was greater vasoconstriction with greater magnitudes of vibration.Conclusions: it is concluded that at the higher frequencies (63, 125, and 250 Hz), the Pacinian channel mediates vibrotactile sensations near threshold and vasoconstriction occurs when vibration is perceptible. At lower frequencies (8, 16, and 31.5 Hz), the Pacinian channel does not mediate sensations near threshold and vasoconstriction commences at greater magnitudes when the Pacinian channel is activate
Do rules control power? GATT articles and arrangements in the Uruguay Round
No full textMany complain and offer evidence that in recent years the GATT system has become more power-oriented, less stable, and less equitable. A concern to reverse this drift was one of the motives that brought the international community to agree to undertake the Uruguay Round. Rules control power, assumed the signers of the Punte del Este declaration, therefore elaborating and extending GATT rules would move the international community toward a fairer, more stable international trading system. Finger and Dhar contend that the opposite is true. Particularly in the 1980s, the elaboration and application of GATT rules has been an exercise in the application of economic and political power, not in its control. GATT rules, in theory, are there to limit national trade restrictions. Finger and Dhar contend that in fact things work the other way around: national practice comes first, and determines what the GATT rules mean. GATT's rules do not put limits on national practices, but provide international santion for these practices. Such rules are not part of the thereforelution but are part of the problem. Theirs is a situation-specific argument, say Finger and Dhar, not a generic one. Their target is not"rules", nor is it"GATT". Rather, it is the GATT rules.Rules of Origin,TF054105-DONOR FUNDED OPERATION ADMINISTRATION FEE INCOME AND EXPENSE ACCOUNT,Common Carriers Industry,Transport and Trade Logistics,Trade Policy
Response of finger circulation to energy equivalent combinations of magnitude and duration of vibration
No full textOBJECTIVES - To investigate the acute response of finger circulation to vibration with different combinations of magnitude and duration but with the same "energy equivalent" acceleration magnitude according to current standards for hand transmitted vibration.METHODS - Finger skin temperature (FST) and finger blood flow (FBF) were measured in the middle fingers of both hands of 10 healthy men who had not used hand held vibrating tools regularly. With a static load of 10 N, the right hand was exposed to 125 Hz vibration with the following unweighted root mean square (rms) acceleration magnitudes and durations of exposure: 44 m/s2 for 30 minutes; 62 m/s2 for 15 minutes; 88 m/s2 for 7.5 minutes; 125 m/s2 for 3.75 minutes; and 176 m/s2 for 1.88 minutes. These vibration exposures produce the same 8 hour energy equivalent frequency weighted acceleration magnitude (~1.4 m/s2 rms) according to international standard ISO 5349 (1986). Finger circulation was measured in both the right (vibrated) and the left (non-vibrated) middle fingers before application of the vibration, and at fixed intervals during exposure to vibration and during a 45 minute recovery period.RESULTS - The FST did not change during exposure to vibration, whereas vibration with any combination of acceleration magnitude and duration produced significant percentage reductions in the FBF of the vibrated finger compared with the FBF before exposure (from 40.1% (95% confidence interval (95% CI) 24.3% to 57.2%) to 61.4% (95% CI 45.0% to 77.8%). The reduction in FBF during vibration was stronger in the vibrated finger than in the non-vibrated finger. Across the five experimental conditions, the various vibration stimuli caused a similar degree of vasoconstriction in the vibrated finger during exposure to vibration. There was a progressive decrease in the FBF of both fingers after the end of exposure to vibration with acceleration magnitudes of 44 m/s2 for 30 minutes and 62 m/s2 for 15 minutes. Significant vasoconstrictor after effects were not found in either finger after exposure to any of the other vibration stimuli with greater acceleration magnitudes for shorter durations.CONCLUSIONS - For the range of vibration magnitudes investigated (44 to 176 m/s2 rms unweighted; 5.5 to 22 m/s2 rms when frequency weighted according to ISO 5349), the vasoconstriction during exposure to 125 Hz vibration was independent of vibration magnitude. The after effect of vibration was different for stimuli with the same energy equivalent acceleration, with greater effects after longer durations of exposure. The energy equivalent acceleration therefore failed to predict the acute effects of vibration both during and after exposure to vibration. Both central and local vasoregulatory mechanisms are likely to be involved in the response of finger circulation to acute exposures to 125 Hz vibration
Localization of the human HF.10 finger gene on a chromosome region (3p21-22) frequently deleted in human cancers
No full textThe finger motif is a tandemly repeated DNA-binding domain recently identified in the primary structure of several eukaryotic transcriptional regulatory proteins. It has been proposed that some members of the finger-gene family are implicated in both normal cell proliferation and differentiation. We isolated several human finger genes by means of hybridization with a finger motif-containing DNA probe. One of these finger genes, HF.10, is expressed at low levels in a variety of human tissues and is down-regulated during the in vitro terminal differentiation of human leukemic myeloid cell lines. By in situ hybridization experiments and analysis of interspecific somatic cell hybrids we mapped the HF.10 gene to 3p21-22, a chromosome region frequently involved in karyotypic rearrangements associated with lung and renal cancer
The measurement of vascular and neurological function in workers exposed to hand-transmitted vibration
No full textFour methods for measuring disorders of vascular function and neurological function associated with occupational exposure to hand-transmitted vibration have been defined by reference to the available literature. For measuring vascular function the methods are: i) measures of the finger systolic blood pressure (FSBP) response to local cooling and ii) measures of the finger skin temperature (FST) response to local cooling. For measuring neurological function the methods are: i) measures of vibrotactile thresholds at the fingertips and ii) measures of thermal thresholds at the fingertips.Measures of the FSBP and the FST response to cold provocation were appraised in 109 dockyard workers. The FST test did not differentiate between 82 healthy subjects and 27 subjects with vibration-induced white finger (VWF) whilst the FSBP test was found to be sensitive, specific and responsive to VWF. Vibrotactile and thermal thresholds were found to be sensitive, specific and responsive to symptoms of numbness in another study of 104 dockyard workers, of whom 67 reported neurological disorders. It was concluded that whilst the above tests could be useful for monitoring the vascular and neurological disorders, a number of improvements to the measurement methods could be worthwhile. Further experiments were carried out to investigate these improvements.The simultaneous measurement of FSBPs on multiple test fingers was developed to improve the practicality of this test when measuring FSBPs on more than one test finger. Increased central sympathetic activity was hypothesised to result from increasing the stimulus by cooling more fingers. In two experiments on 12 healthy subjects, it was found that FSBPs measured simultaneously on four test fingers gave similar results to FSBP measurements on one test finger. Simultaneous FSBP measurements on four test fingers had comparable repeatability to measurements on one test finger. It was concluded that measuring FSBPs on multiple test fingers is a useful improvement to this test.When measuring FSBPs, changing the order of presentation and the period of recovery between thermal stimuli was hypothesised to influence the results by altering central sympathetic activity. In 12 healthy subjects it was found that the order of presentation of thermal stimuli was not important but that inter-subject variability increased when recovery was allowed between thermal stimuli. It was concluded that minimising the time interval between successive applications of thermal provocation reduces undesirable inter-subject variability. Another study on 12 healthy subjects showed that different reference measurement locations give different results. It was concluded that the thumb is suitable location for making reference measurements.The FSBP test and the FST test both involve application of cold provocation. The two tests are sometimes performed in succession but multiple thermal provocations may have cumulative effects on central sympathetic activity. When the two vascular tests were performed in succession on 36 subjects, including 12 subjects with VWF, any effects of the order of test presentation were small although a test performed first tended to be more repeatable. It was concluded that if both tests are performed consecutively, greater emphasis should be placed on the test performed first. The data for the FST test were reanalysed and showed that the sensitivity and specificity to VWF of this test is improved by changing the method of interpreting the results. Three methods of interpreting the FST response to cold provocation that represent an improvement to the test are suggested.The two vascular tests have been shown in the literature to be repeatable for healthy subjects but not for subjects with VWF. The repeatability of the vascular tests was assessed in 36 subjects (12 manual workers, 12 office workers and 12 subjects with VWF). The repeatability of both tests was found to be low amongst workers with VWF; some of these subjects showed a negative test result on one occasion and a positive test result on another occasion. It was concluded that a repeat test may be required when a false negative result is obtained.For the vibrotactile threshold test, the skin-stimulus contact force is usually controlled. Controlling the skin indentation would simplify measurement equipment. An experiment on ten healthy subjects investigated the relationship between skin-stimulus contact force, skin indentation and vibrotactile thresholds. It was concluded that the vibrotactile threshold test could be improved by implementing control of skin-indentation. Skin indentations giving comparable vibrotactile thresholds to those obtained using controlled contact forces were identified.It is concluded that a test battery comprising the four test methods identified from the literature and subsequently developed during the course of this research can be used to monitor disorders of both vascular and neurological function associated with occupational exposure to hand-transmitted vibration. A number of recommendations are made for further improvements that might be achievable as a result of further work
Magnitude of acute exposures to vibration and finger circulation
No full textObjectives. Changes in finger circulation were studied during and after acute exposure to increasing magnitudes of hand-transmitted vibration. Methods. Finger skin temperature (FST) and finger blood flow (FBF) were measured in the middle fingers of both hands of 10 healthy men. The right hand was exposed for 15 minutes to 125-Hz vibration with acceleration magnitudes of either 5.5, 22, 44, or 62 m/s2 root-mean-square. The measures of finger circulation were taken before the vibration, at fixed intervals during exposure, and during a 45-minute recovery period. Results The FST did not change during vibration exposure, whereas vibration of any magnitude provoked significant reductions in the FBF of the vibrated finger when compared with the preexposure FBF and the contralateral (nonvibrated finger) FBF. Vasoconstrictor aftereffects (ie, during recovery) were observed in both fingers after the end of exposure to vibration magnitudes greater than 22 m/s2 root-mean-square. The higher the vibration magnitude, the stronger the reduction of FBF in either finger during both vibration exposure and the recovery period. This effect was stronger in the vibrated finger than in the nonvibrated finger during both periods. Conclusions. Acute exposure to 125-Hz vibration can reduce FBF in both the vibrated and the nonvibrated finger, and the degree of digital vasoconstriction is related to the magnitude of the vibration. The pattern of the hemodynamic changes during and after vibration exposure suggests that complex vasomotor mechanisms are involved in the response of digital vessels to acute vibration.</p
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