The focus wave mode (FWM), which is a time-dependent beam field that propagates at the speed of light without dispersion and retains its shape in space, is an interesting wave object with possible implications for syn...
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The focus wave mode (FWM), which is a time-dependent beam field that propagates at the speed of light without dispersion and retains its shape in space, is an interesting wave object with possible implications for synthesizing focused fields under transient conditions. To explore this potential, it is necessary to understand fully the properties of this wave field. It is already known that the FWM is a homogeneous solution of the wave equation, which is related in a special way to the field of a source moving on a complex trajectory parallel to the real axis of propagation. This suggests that there may be a connection between the FWM and the conventional free-space Green’s function. It is shown here that the FWM is related, in fact, to a source-free combination of causal and anticausal free-space Green’s functions and that one can formulate a bilateral transform pair relating these solutions. This new representation is then analyzed by using the spectral theory of transients to establish the properties of the FWM in terms of a distribution of transient plane waves. The spectral decomposition in the spatial wave-number domain reveals that the FWM is synthesized by both forward- and backward-propagating plane waves that are restricted to the visible spectrum. Asymptotic considerations show that the dominant mechanism is constructive interference of the backward-propagating waves. Taken together, the Green’s-function and spectral approaches grant further insight into the physical and spectral properties of the FWM. The conclusions cast doubt on the possibility of embedding the FWM within a causal excitation scheme.
Background: Polyglutamine expansion of the ataxin-7 protein, a subunit of the SAGA (Spt-Ada-Gcn5-acetyltransferase) complex, causes spinocerebellar ataxia type 7. Results: Polyglutamine-expanded ataxin-7 aberrantly bi...
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Background: Polyglutamine expansion of the ataxin-7 protein, a subunit of the SAGA (Spt-Ada-Gcn5-acetyltransferase) complex, causes spinocerebellar ataxia type 7. Results: Polyglutamine-expanded ataxin-7 aberrantly binds to SAGA, affecting Gcn5 acetyltransferase activity at SAGA-regulated genes. Conclusion: Ataxin-7 exhibits a dominant-negative effect on Gcn5 catalytic activity in vivo. Significance: We show a direct dominant effect of polyglutamine-expanded ataxin-7 on SAGA acetyltransferase function. Spinocerebellar ataxia type 7 (SCA7) is a neurodegenerative disease caused by polyglutamine (polyQ) expansion within the N-terminal region of the ataxin-7 protein, a known subunit of the SAGA complex. Although the mechanisms of SCA7 pathogenesis remain poorly understood, previous studies have shown perturbations in SAGA histone acetyltransferase function and transcriptional alterations. We sought to determine whether and how polyQ-expanded ataxin-7 affects SAGA catalytic activity. Here, we determined that polyQ-expanded ataxin-7 directly bound the Gcn5 catalytic core of SAGA while in association with its regulatory proteins, Ada2 and Ada3. This caused a significant decrease in Gcn5 histone acetyltransferase activity in vitro and in vivo at two SAGA-regulated galactose genes, GAL1 and GAL7. However, Gcn5 occupancy at the GAL1 and GAL7 promoters was increased in these cells, revealing a dominant-negative phenotype of the polyQ-expanded ataxin-7-incorporated, catalytically inactive SAGA. These findings suggest a dominant mechanism of polyQ-mediated SAGA inhibition that potentially contributes to SCA7 disease pathogenesis.
Arrays of vertically aligned Fe-filled multi-wall carbon nanotubes (MWNTs) on oxidized silicon substrates were prepared by pyrolysis of ferrocene in a dual furnace system and characterized by electron microscopy and m...
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Arrays of vertically aligned Fe-filled multi-wall carbon nanotubes (MWNTs) on oxidized silicon substrates were prepared by pyrolysis of ferrocene in a dual furnace system and characterized by electron microscopy and magnetometry measurement. The effect of the growth temperature on both the filled nanotube morphology and their magnetic behavior was studied. Increasing the growth temperature in the range of 845-1035 degrees C the nanotube alignment becomes worse and the diameter of the encapsulated Fe nanowires increases from 10 to 40 nm. Both the coercivity and the remanence ratio of the arrays of Fe-filled MNVNTs decrease with the increase of the growth temperature. Factors causing the observed magnetic behavior are discussed.
Deinococcus radiodurans (Dr) has a significantly more robust DNA repair response than Escherichia coil (Ec), which helps it survive extremely high doses of ionizing radiation and prolonged periods of desiccation. DrRe...
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Deinococcus radiodurans (Dr) has a significantly more robust DNA repair response than Escherichia coil (Ec), which helps it survive extremely high doses of ionizing radiation and prolonged periods of desiccation. DrRecA protein plays an essential part in this DNA repair capability. In this study we directly compare the binding of DrRecA and EcRecA to the same set of short, defined single (ss) and double stranded (ds) DNA oligomers. In the absence of cofactors (ATP gamma S or ADP), DrRecA binds to dsDNA oligomers more than 20 fold tighter than EcRecA, and binds ssDNA up to 9 fold tighter. Binding to dsDNA oligomers in the absence of cofactor presumably predominantly monitors DNA end binding, and thus suggests a significantly higher affinity of DrRecA for ds breaks. Upon addition of ATP gamma S, this species-specific affinity difference is nearly abolished, as ATP gamma S significantly decreases the affinity of DrRecA for DNA. Other findings include that: (I) both proteins exhibit a dependence of binding affinity on the length of the ssDNA oligomer, but not the dsDNA oligomer;(2) the salt dependence of binding is modest for both species of RecA, and (3) in the absence of DNA, DrRecA produces significantly shorter and/or fewer free-filaments in solution than does EcRecA. The results suggest intrinsic biothermodynamic properties of DrRecA contribute directly to the more robust DNA repair capabilities of D. radiodurans. (C) 2015 Elsevier B.V. All rights reserved.
One hundred female patients scheduled for elective breast surgery (mean age 60 +/- 11 years) were randomly assigned to receive one of two premedications: ketobemidone (Ketogan(R)) 1-1.5 ml or midazolam 4-5 mg, intramu...
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One hundred female patients scheduled for elective breast surgery (mean age 60 +/- 11 years) were randomly assigned to receive one of two premedications: ketobemidone (Ketogan(R)) 1-1.5 ml or midazolam 4-5 mg, intramuscularly. The effects on preoperative anxiety and postoperative emetic sequelae were studied. All patients were anaesthetised with thiopentone, fentanyl and atracurium, and ventilated with a mixture of nitrous oxide in oxygen with supplementary isoflurane. Sixty-nine percent of the midazolam- and 50% of the ketobemidone-premedicated patients experienced a reduction in anxiety. Midazolam was found to be more effective than ketobemidone in reducing anxiety among more tense patients - those with a VAS grading before premedication of 2 or more (P < 0.05). Midazolam-premedicated patients were also assessed by observers as being more relaxed (P < 0.05). No difference was seen in the frequency of emetic sequelae: 20 patients in the midazolam group and 14 patients in the ketobemidone group vomited once or more during the 24-h observation period. There was no difference between the two groups in time until an analgetic was required. In conclusion, midazolam seemed more effective in reducing preoperative anxiety than ketobemidone without any negative effects on postoperative emesis or time until an analgetic was required.
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