Search results for "Light"
showing 10 items of 3575 documents
The N-terminal domain of the light-harvesting chlorophyll a/b-binding protein complex (LHCII) is essential for its acclimative proteolysis.
2000
AbstractVariations in the amount of the light-harvesting chlorophyll a/b-binding protein complex (LHCII) is essential for regulation of the uptake of light into photosystem II. An endogenous proteolytic system was found to be involved in the degradation of LHCII in response to elevated light intensities and the proteolysis was shown to be under tight regulation [Yang, D.-H. et al. (1998) Plant Physiol. 118, 827–834]. In this study, the substrate specificity and recognition site towards the protease were examined using reconstituted wild-type and mutant recombinant LHCII. The results show that the LHCII apoprotein and the monomeric form of the holoprotein are targeted for proteolysis while t…
NuSTAR and NICER reveal IGR J17591-2342 as a new accreting millisecond X-ray pulsar
2018
We report the discovery by the Nuclear Spectroscopic Telescope Array (NuSTAR) and the Neutron Star Interior Composition Explorer (NICER) of the accreting millisecond X-ray pulsar IGR J17591-2342. Coherent X-ray pulsations around 527.4 Hz (1.9 ms) with a clear Doppler modulation were detected. This implies an orbital period of ∼8.8 h and a projected semi-major axis of ∼1.23 lt-s. With the binary mass function, we estimate a minimum companion mass of 0.42 M, obtained assuming a neutron star mass of 1.4[subscript ⊙] and an inclination angle lower than 60°, as suggested by the absence of eclipses or dips in the light curve of the source. The broad-band energy spectrum, obtained by combining NuS…
Aperiodic variability of low-mass X-ray binaries at very low frequencies
2003
We have obtained discrete Fourier power spectra of a sample of persistent low-mass neutron-star X-ray binaries using long-term light curves from the All Sky Monitor on board the Rossi X-ray Timing Explorer. Our aim is to investigate their aperiodic variability at frequencies in the range 1 x 10^{-7}-5 x 10^{-6} Hz and compare their properties with those of the black-hole source Cyg X-1. We find that the classification scheme that divides LMXBs into Z and atoll sources blurs at very low frequencies. Based on the long-term (~ years) pattern of variability and the results of power-law fits (P ~ v^{-a}) to the 1 x 10^{-7}-5 x 10^{-6} Hz power density spectra, low-mass neutron-star binaries fall…
3D reconstruction of hot metallic surfaces for industrial part characterization
2009
During industrial forging of big hot metallic shells, it is necessary to regularly measure the dimensions of the parts, especially the inner and outer diameters and the thickness of the walls, in order to decide when to stop the forging process. The inner and outer diameters of the shells range from 4 to 6 meters and to measure them a large ruler is placed horizontally at the end of the shell. Two blacksmiths standing on each side of the ruler at about ten meters from it visually reads the graduations on the ruler in order to determine the inner and outer diameters from which the thickness of the wall is determined. This operation is carried out several times during a forging process and it…
Objective Amplitude of Accommodation Computed from Optical Quality Metrics Applied to Wavefront Outcomes
2009
Purpose: We studied the accuracy and precision of 32 objective wavefront methods for finding the amplitude of accommodation obtained in 180 eyes. Methods: Ocular accommodation was stimulated with 0.5 D steps in target vergence spanning the full range of accommodation for each subject. Subjective monocular amplitude of accommodation was measured using two clinical methods, using negative lenses and with a custom Badal optometer. Results: Both subjective methods gave similar results. Results obtained from the Badal optometer where used to test the accuracy of the objective methods. All objective methods showed lower amplitude of accommodation that the subjective ones by an amount that varied …
Response of pineal serotonin N-acetyltransferase activity in male guinea pigs exposed to light pulses at night.
1988
Serotonin N-acetyltransferase (NAT), which is crucial for the formation of melatonin, undergoes a typical day/night rhythm in the pineal gland with low levels during daytime and high levels at night. Short pulses of light given at night have been shown to rapidly depress NAT activity in some species, but not in others, the reasons for this difference being unclear. As diurnality and nocturnality of the experimental animals may play a role and since diurnally active animals have been little investigated in this respect, in the present study the diurnally active guinea pig was investigated. Male guinea pigs kept under a lighting regimen of LD 12:12 (lights off at 1700 hrs) were killed between…
Poly(ethylene oxide)-block-poly(n-butyl acrylate)-block-poly(acrylic acid) triblock terpolymers with highly asymmetric hydrophilic blocks: synthesis …
2013
The synthesis and aggregation behaviour in aqueous media of novel amphiphilic poly(ethylene oxide)-block-poly(n-butyl acrylate)-block-poly(acrylic acid) (PEO–PnBA–PAA) triblock terpolymers were studied. Terpolymers composed of two highly asymmetric hydrophilic PEO (113 monomer units) and PAA (10–17 units) blocks, and a longer soft hydrophobic PnBA block (163 or 223 units) were synthesized by atom transfer radical polymerisation (ATRP) of n-butyl acrylate and tert-butyl acrylate (tBA), followed by selective hydrolysis of the PtBA blocks. These terpolymers are not directly soluble in water but form defined spherical micelles by employing the dialysis method as confirmed by dynamic light scatt…
Aequorin-expressing yeast emits light under electric control
2011
In this study, we show the use of direct external electrical stimulation of a jellyfish luminescent calcium-activated protein, aequorin, expressed in a transgenic yeast strain. Yeast cultures were electrically stimulated through two electrodes coupled to a standard power generator. Even low (1.5. V) electric pulses triggered a rapid light peak and serial light pulses were obtained after electric pulses were applied periodically, suggesting that the system is re-enacted after a short refraction time. These results open up a new scenario, in the very interphase between synthetic biology and cybernetics, in which complex cellular behavior might be subjected to electrical control.
Contra la patologización intensiva en términos de derechos humanos: Activismo gordo en Argentina
2020
This work addresses the way in which Argentine Fat Activism has developed, in recent years, the demand for depathologization of fatness, taking elements from critical discourses on the health of fat people to frame them in a perspective typical of the Human Rights. First, the contemporary fat body is described in terms of stigma and discrimination, especially in the health field. Then, they refer to a series of critical positions on the pathologization and medicalization of fatness from the biomedical perspective, Fat Studies and Fat Activism. Lastly, a series of interventions that the Argentine activist collective Taller Hacer la Vista Gorda produced between 2017 and 2020 were considered, …