We investigate the lifetime and luminescence quantum efficiency of excitons in extremely high-purity diamond grown by the chemical vapor deposition method. A clear correlation is found between the ...diffusion coefficient, lifetime, and quantum efficiency. The effect of small strain (magnitude ≈ 10−5) assessed using birefringence is also clarified thanks to the effective absence of impurity traps. A surface recombination model, extended for nonradiative recombination at dislocations due to diffusion, is proposed to explain the temperature dependence from 4 to 300 K, which facilitates the derivation of the radiative lifetime. The proposed model is generally applicable to a mixture of excitons and carriers in a wide range of materials with high exciton binding energies.
In magnetoelectric and multiferroic materials, the magnetic degree of freedom can be controlled by electric field, and vice versa. A significant amount of research has been devoted to exploiting this ...effect for magnetoelectric data storage and manipulation devices driven by d.c. electric fields1–4. Aiming at ever-faster schemes of magnetoelectric manipulation, a promising alternative approach offers similar control on a femtosecond timescale, relying on laser pulses4–6 to control both the charge7,8 and the magnetic9,10 order of solids. Here we photo-induce magnetoelectricity and multiferroicity in CuB2O4 on a sub-picosecond timescale. This process is triggered by the resonant optical generation of the highest-energy magnetic excitations—magnons with wavevectors near the edges of the Brillouin zone. The most striking consequence of the photo-excitation is that the absorption of light becomes non-reciprocal, which means that the material exhibits a different transparency for two opposite directions of propagation of light. The photo-induced magnetoelectricity does not show any decay on the picosecond timescale. Our findings uncover a path for ultrafast manipulations of the intrinsic coupling between charges and spins in multiferroics4, which may reveal unexplored magnetic configurations and unravel new functionalities in terms of femtosecond optical control of magnetism.
Antarctic minke whales, Balaenoptera bonaerensis, breed in tropical and temperate waters of the Southern Hemisphere in winter and feed in Antarctic grounds in the austral summer. These seasonal ...migrations could be less defined than those of other whale species, but the evidence is scanty. We quantitatively describe the epibiotic fauna of Antarctic minke whales and explore its potential to trace migrations. Seven species were found on 125 out of 333 examined Antarctic minke whales captured during the last Antarctic NEWREP-A expedition in the Southern Ocean: the amphipod Balaenocyamus balaenopterae (prevalence = 22.2%), the copepod Pennella balaenoptera (0.6%); three coronulid, obligate barnacles, Xenobalanus globicipitis (11.1%), Coronula reginae (8.7%), C. diadema (0.9%); and two lepadid, facultative barnacles, Conchoderma auritum (9.0%) and C. virgatum (0.3%). Species with prevalence > 8% exhibited a modest increase in their probability of occurrence with whale body length. Data indicated positive associations between coronulid barnacles and no apparent recruitment in Antarctic waters. All specimens of X. globicipitis were dead, showing progressive degradation throughout the sampling period, and a geographic analysis indicated a marked drop of occurrence where the minimum sea surface temperature is < 12 °C. Thus, field detection -with non-lethal methodologies, such as drones- of coronulid barnacles, especially X. globicipitis, on whales in the Southern Ocean could evince seasonal migration. Future investigations on geographical distribution, growth rate, and degradation (for X. globicipitis) could also assist in timing whales' migration.
Increased incidence of lifestyle diseases as side-effects of antiretroviral therapy (ART) have been reported in people living with HIV (PLWH). Few studies have evaluated obesity and hidden obesity in ...Japanese PLWH and their association with ART. In order to provide more appropriate drug selection and lifestyle guidance, we investigated the relationship between the effects of HIV infection and ART on the body composition of Japanese PLWH.
PLWH who visited the outpatient clinic and had body composition measured using the body composition analyzer InBody 570 were included in this study. Medications, comorbidities, and blood test data were obtained. Body mass index (BMI), body fat percentage, and skeletal muscle mass index (SMI) were measured.
In this study, 543 patients were included. Based on body shape, patients were classified into a thin group (13), normal weight group (14), hidden obesity group (158), apparent obesity group (14), and obesity group (218). Compared with the normal weight group, the hidden obesity group had a higher prevalence of comorbidities and a lower SMI.
PLWH are more likely to have obesity than the general population, indicating that hidden obesity is common even among those with a normal BMI. It is important to measure body fat percentage along with body weight, as hidden obesity can be missed. Further investigation of the effects of ART on body composition is needed.
The transfer of spin angular momentum to a nanomagnet from a spin polarized current provides an efficient means of controlling the magnetization direction in nanomagnets. A unique consequence of this ...spin torque is that the spontaneous oscillations of the magnetization can be induced by applying a combination of a dc bias current and a magnetic field. Here we experimentally demonstrate a different effect, which can drive a nanomagnet into spontaneous oscillations without any need of spin torque. For the demonstration of this effect, we use a nano-pillar of magnetic tunnel junction (MTJ) powered by a dc current and connected to a coplanar waveguide (CPW) lying above the free layer of the MTJ. Any fluctuation of the free layer magnetization is converted into oscillating voltage via the tunneling magneto-resistance effect and is fed back into the MTJ by the CPW through inductive coupling. As a result of this feedback, the magnetization of the free layer can be driven into a continual precession. The combination of MTJ and CPW behaves similar to a laser system and outputs a stable rf power with quality factor exceeding 10,000.
We propose and demonstrate polarization rotation of a terahertz (THz) electromagnetic wave by using two-dimensional gratings consisting of two displaced layers of gold film with complimentary chiral ...patterns with four-fold symmetry. We develop a time domain THz polarimetry method with three wire grid polarizers and distinguish optical activity from optical anisotropy. We obtain the isotropic polarization rotation of a terahertz wave free from the birefringence of the structures. Results indicate the possibility of controlling THz polarization with artificial chiral structures fabricated with thin metal films.
A
bstract
Remarkable simplification arises from considering vortex equations in the large winding limit. This was recently used 1 to display all sorts of vortex zeromodes, the orientational, ...translational, fermionic as well as semi-local, and to relate them to the apparently distinct phenomena of the Nielsen-Olesen-Ambjorn magnetic instabilities. Here we extend these analyses to more general types of BPS nonAbelian vortices, taking as a prototype a system with gauged U
0
(1) × SU
ℓ
(
N
) × SU
r
(
N
) symmetry where the VEV of charged scalar fields in the bifundamental representation breaks the symmetry to SU(
N
)
ℓ+
r
. The presence of the massless SU(
N
)
ℓ+
r
gauge fields in 4
D
bulk introduces all sorts of non-local, topological phenomena such as the nonAbelian Aharonov-Bohm effects, which in the theory with global SU
r
(
N
) group (
g
r
= 0) are washed away by the strongly fluctuating orientational zeromodes in the worldsheet. Physics changes qualitatively at the moment the right gauge coupling constant
g
r
is turned on.
The hippocampus is critical to healthy cognition, yet results in the current study show that action video game players have reduced grey matter within the hippocampus. A subsequent randomised ...longitudinal training experiment demonstrated that first-person shooting games reduce grey matter within the hippocampus in participants using non-spatial memory strategies. Conversely, participants who use hippocampus-dependent spatial strategies showed increased grey matter in the hippocampus after training. A control group that trained on 3D-platform games displayed growth in either the hippocampus or the functionally connected entorhinal cortex. A third study replicated the effect of action video game training on grey matter in the hippocampus. These results show that video games can be beneficial or detrimental to the hippocampal system depending on the navigation strategy that a person employs and the genre of the game.
Summary
Outer membrane protein PG27 is essential for secretion/maturation of conserved C‐terminal domain (CTD) proteins such as gingipains, HagA, and PG0026. To determine the binding partner(s) of ...PG27, we used a Porphyromonas gingivalis mutant strain, 83K48, which expressed functional histidine‐tagged PG27. Purification of histidine‐tagged PG27 from 83K48 found that 136‐kDa and 264‐kDa proteins accompanied histidine‐tagged PG27. Mass spectrometry revealed the 136‐kDa protein and 264‐kDa protein to be PG0026 and PG1837 (HagA), respectively. PG0026 is a C‐terminal signal peptidase which cleaves the CTDs of other CTD proteins. A cross‐linking and a native electrophoresis studies suggested the interaction between histidine‐tagged PG27 and HagA and the interaction between histidine‐tagged PG27 and PG0026. We constructed Porphyromonas gingivalis gene disrupting mutants, and characterized them. PG0026 was required for the full activities of gingipains, whereas HagA was not. A mutation disrupting PG0026 affected localization of PG27, but a mutation disrupting PG1837 showed little effect on the expression and localizations of PG27 and PG0026. To determine the functional role of HagA, we used PG1837‐disruptant 83K54 which expressed functional histidine‐tagged PG27. Histidine‐tagged PG27 in 83K54 was co‐purified with not only PG0026 but also several contaminated proteins. These results suggest that PG0026 interacts with PG27 in the absence of HagA, and that the binding state of a PG27‐PG0026 complex was affected and stabilized by HagA. Taken together, these data suggest that secreted PG0026 anchors to the cell by interacting with PG27, is stabilized by HagA, and functions in processing of other CTD proteins such as gingipains.
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