A linear array of periodically spaced and individually controllable skyrmions is introduced as a magnonic crystal. It is numerically demonstrated that skyrmion nucleation and annihilation can be ...accurately controlled by a nanosecond spin polarized current pulse through a nanocontact. Arranged in a periodic array, such nanocontacts allow the creation of a skyrmion lattice that causes a periodic modulation of the waveguide’s magnetization, which can be dynamically controlled by changing either the strength of an applied external magnetic field or the density of the injected spin current through the nanocontacts. The skyrmion diameter is highly dependent on both the applied field and the injected current. This implies tunability of the lowest band gap as the skyrmion diameter directly affects the strength of the pinning potential. The calculated magnonic spectra thus exhibit tunable allowed frequency bands and forbidden frequency bandgaps analogous to that of conventional magnonic crystals where, in contrast, the periodicity is structurally induced and static. In the dynamic magnetic crystal studied here, it is possible to dynamically turn on and off the artificial periodic structure, which allows switching between full rejection and full transmission of spin waves in the waveguide. These findings should stimulate further research activities on multiple functionalities offered by magnonic crystals based on periodic skyrmion lattices.
Aim
To investigate whether static magnetic fields (SMFs) have a positive effect on the migration and dentinogenesis of dental pulp stem cells (DPSCs) to promote reparative dentine formation.
...Methodology
In vitro scratch assays and a traumatic pulp exposure model were performed to evaluate the effect of 0.4‐Tesla (T) SMF on DPSC migration. The cytoskeletons of the DPSCs were identified by fluorescence immunostaining and compared with those of a sham‐exposed group. Dentinogenic evaluation was performed by analysing the expressions of DMP‐1 and DSPP marker genes using a quantitative real‐time polymerase chain reaction (qRT‐PCR) process. Furthermore, the formation of calcified deposits was examined by staining the dentinogenic DPSCs with Alizarin Red S dye. Finally, the role played by the p38 MAPK signalling pathway in the migration and dentinogenesis of DPSCs under 0.4‐T SMF was investigated by incorporating p38 inhibitor (SB203580) into the in vitro DPSC experiments. The Student's t‐test and the Kruskal–Wallis test followed by Dunn's post hoc test with a significance level of P < 0.05 were used for statistical analysis.
Results
The scratch assay results revealed that the application of 0.4‐T SMF enhanced DPSCs migration towards the scratch wound (P < 0.05). The cytoskeletons of the SMF‐treated DPSCs were found to be aligned perpendicular to the scratch wound. After 20 days of culture, the SMF‐treated group had a greater number of out‐grown cells than the sham‐exposed group (nonmagnetized control). For the SMF‐treated group, the DMP‐1 (P < 0.05) and DSPP genes (P < 0.05), analysed by qRT‐PCR, exhibited a higher expression. The distribution of calcified nodules was also found to be denser in the SMF‐treated group when stained with Alizarin Red S dye (P < 0.05). Given the incorporation of p38 inhibitor SB203580 into the DPSCs, cell migration and dentinogenesis were suppressed. No difference was found between the SMF‐treated and sham‐exposed cells (P > 0.05).
Conclusion
0.4‐T SMF enhanced DPSC migration and dentinogenesis through the activation of the p38 MAPK‐related pathway.
Magnetic skyrmions are particle-like magnetization configurations which can be found in materials with broken inversion symmetry. Their topological nature allows them to circumvent around random ...pinning sites or impurities as they move within the magnetic layer, which makes them interesting as information carriers in memory devices. However, when the skyrmion is driven by a current, a Magnus force is generated which leads to the skyrmion moving away from the direction of the conduction electron flow. The deflection poses a serious problem to the realization of skyrmion-based devices, as it leads to skyrmion annihilation at the film edges. Here, we show that it is possible to guide the movement of the skyrmion and prevent it from annihilating by surrounding and compressing the skyrmion with strong local potential barriers. The compressed skyrmion receives higher contribution from the spin transfer torque, which results in the significant increase of the skyrmion speed.
Circulating subclinical lipopolysaccharide (LPS) occurs in health and disease. Ingesting high fatty meals increases LPS that cause metabolic endotoxemia. Subclinical LPS in periodontal disease may ...impair endothelial function. The heart may be targeted as cardiac cells express TLR4, the LPS receptor. It was hypothesized that recurrent exposure to subclinical LPS increases mortality and causes cardiac fibrosis.
C57Bl/6 mice were injected with intraperitoneal saline (control), low dose LPS (0.1 or 1 mg/kg), or moderate dose LPS (10 or 20 mg/kg), once a week for 3 months. Left ventricular (LV) function (echocardiography), hemodynamics (tail cuff pressure) and electrocardiograms (telemetry) were measured. Cardiac fibrosis was assessed by picrosirius red staining and LV expression of fibrosis related genes (QRT-PCR). Adult cardiac fibroblasts were isolated and exposed to LPS.
LPS injections transiently increased heart rate and blood pressure (<6 hours) and mildly decreased LV function with full recovery by 24 hours. Mice tolerated weekly LPS for 2-3 months with no change in activity, appearance, appetite, weight, blood pressure, LV function, oximetry, or blood chemistries. Mortality increased after 60-90 days with moderate, but not low dose LPS. Arrhythmias occurred a few hours before death. LV collagen fraction area increased dose-dependently from 3.0±0.5% (SEM) in the saline control group, to 5.6±0.5% with low dose LPS and 9.7±0.9% with moderate dose LPS (P<0.05 moderate vs low dose LPS, and each LPS dose vs control). LPS increased LV expression of collagen Iα1, collagen IIIα1, MMP2, MMP9, TIMP1, periostin and IL-6 (P<0.05 moderate vs low dose LPS and vs control). LPS increased α-SMA immunostaining of myofibroblasts. LPS dose-dependently increased IL-6 in isolated adult cardiac fibroblasts.
Recurrent exposure to subclinical LPS increases mortality and induces cardiac fibrosis.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Despite the inefficiencies associated with current-induced spin torques, they remain the predominant mode of skyrmion propulsion. In this work, we demonstrate numerically that skyrmions can be ...transported much more efficiently with a voltage-controlled magnetic anisotropy (VCMA) gradient. An analytical model was developed to understand the underlying skyrmion dynamics on a track under the VCMA conditions. Our calculations reveal that the repulsive skyrmion-edge interaction not only prevents the skyrmion from annihilating but also generates most of the skyrmion propulsion. A multiplexed array of gate electrodes can be used to create discrete anisotropy gradients over a long distance, leading to the formation of a series of translatable skyrmion potential wells. Due to the strong confining potentials, skyrmions are transported at a 70% higher packing density. Finally, we demonstrated that this form of skyrmion propulsion can also be implemented on almost any 2D geometry, providing improved versatility over current-induced methods.
To systematic review and meta-analyse the association and mechanistic links between atrial fibrillation (AF) and cognitive impairment.
PubMed, EMBASE, and Cochrane Library were searched up to 27 ...March 2021 and yielded 4534 citations. After exclusions, 61 were analysed; 15 and 6 studies reported on the association of AF and cognitive impairment in the general population and post-stroke cohorts, respectively. Thirty-six studies reported on the neuro-pathological changes in patients with AF; of those, 13 reported on silent cerebral infarction (SCI) and 11 reported on cerebral microbleeds (CMB). Atrial fibrillation was associated with 39% increased risk of cognitive impairment in the general population n = 15: 2 822 974 patients; hazard ratio = 1.39; 95% confidence interval (CI) 1.25-1.53, I2 = 90.3%; follow-up 3.8-25 years. In the post-stroke cohort, AF was associated with a 2.70-fold increased risk of cognitive impairment adjusted odds ratio (OR) 2.70; 95% CI 1.66-3.74, I2 = 0.0%; follow-up 0.25-3.78 years. Atrial fibrillation was associated with cerebral small vessel disease, such as white matter hyperintensities and CMB (n = 8: 3698 patients; OR = 1.38; 95% CI 1.11-1.73, I2 = 0.0%), SCI (n = 13: 6188 patients; OR = 2.11; 95% CI 1.58-2.64, I2 = 0%), and decreased cerebral perfusion and cerebral volume even in the absence of clinical stroke.
Atrial fibrillation is associated with increased risk of cognitive impairment. The association with cerebral small vessel disease and cerebral atrophy secondary to cardioembolism and cerebral hypoperfusion may suggest a plausible link in the absence of clinical stroke. PROSPERO CRD42018109185.
Delaying intubation in patients who fail high-flow nasal cannula (HFNC) may result in increased mortality. The ROX index has been validated to predict HFNC failure among pneumonia patients with acute ...hypoxemic respiratory failure (AHRF), but little information is available for non-pneumonia causes. In this study, we validate the ROX index among AHRF patients due to both pneumonia or non-pneumonia causes, focusing on early prediction.
This was a retrospective observational study in eight Singapore intensive care units from 1 January 2015 to 30 September 2017. All patients >18 years who were treated with HFNC for AHRF were eligible and recruited. Clinical parameters and arterial blood gas values at HFNC initiation and one hour were recorded. HFNC failure was defined as requiring intubation post-HFNC initiation.
HFNC was used in 483 patients with 185 (38.3%) failing HFNC. Among pneumonia patients, the ROX index was most discriminatory in pneumonia patients one hour after HFNC initiation AUC 0.71 (95% CI 0.64-0.79), with a threshold value of <6.06 at one hour predicting HFNC failure (sensitivity 51%, specificity 80%, positive predictive value 61%, negative predictive value 73%). The discriminatory power remained moderate among pneumonia patients upon HFNC initiation AUC 0.65 (95% CI 0.57-0.72), non-pneumonia patients at HFNC initiation AUC 0.62 (95% CI 0.55-0.69) and one hour later AUC 0.63 (95% CI 0.56-0.70).
The ROX index demonstrated moderate discriminatory power among patients with either pneumonia or non-pneumonia-related AHRF at HFNC initiation and one hour later.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract Brown dwarfs (BDs) in ultra-short-period orbits around white dwarfs (WDs) offer a unique opportunity to study the properties of tidally locked, fast-rotating (1–3 hr), and highly irradiated ...atmospheres. Here we present phase-resolved spectrophotometry of the WD–BD binary SDSS 1557, which is the fifth WD–BD binary in our six-object sample. Using the Hubble Space Telescope Wide Field Camera 3 Near-infrared G141 instrument, the 1.1–1.7 μ m phase curves show rotational modulations with semiamplitudes of 10.5% ± 0.1%. We observe a wavelength-dependent amplitude, with longer wavelengths producing larger amplitudes, while no wavelength-dependent phase shifts were identified. The phase-resolved extracted BD spectra exhibit steep slopes and are nearly featureless. A simple radiative energy redistribution atmospheric model re-creates the hemisphere-integrated brightness temperatures at three distinct phases and finds evidence for weak redistribution efficiency. Our model also predicts a higher inclination than previously published. We find that SDSS 1557B, the second most irradiated BD in our sample, is likely dominated by clouds on the nightside, whereas the featureless dayside spectrum is likely dominated by H − opacity and a temperature inversion, much like the other highly irradiated BD EPIC 2122B.
Abstract
With infrared flux contrasts larger than typically seen in hot Jupiter, tidally locked white dwarf–brown dwarf binaries offer a superior opportunity to investigate atmospheric processes in ...irradiated atmospheres. NLTT5306 is such a system, with a
M
BD
= 52 ± 3
M
Jup
brown dwarf, orbiting a
T
eff
= 7756 ± 35 K white dwarf with an ultra-short period of ∼102 minutes. We present Hubble Space Telescope/Wide Field Camera 3 spectroscopic phase curves of NLTT5306, consisting of 47 spectra from 1.1 to 1.7
μ
m with an average signal-to-noise ratio ∼ 65 per wavelength. We extracted the phase-resolved spectra of the brown dwarf NLTT5306B, finding a small <100 K day–night temperature difference (∼5% of the average day-side temperature). Our best-fit model phase curves revealed a complex wavelength-dependence on amplitudes and relative phase offsets, suggesting longitudinal–vertical atmospheric structure. The night-side spectrum was well fit by a cloudy, nonirradiated atmospheric model while the day side was best matched by a cloudy, weakly irradiated model. Additionally, we created a simple radiative energy redistribution model of the atmosphere and found evidence for efficient day-to-night heat redistribution and a moderately high Bond albedo. We also discovered an internal heat flux much higher than expected given the published system age, leading to an age reassessment that resulted in NLTT5306B most likely being much younger. We find that NLTT5306B is the only known significantly irradiated brown dwarf where the global temperature structure is not dominated by external irradiation, but rather its own internal heat. Our study provides an essential insight into the drivers of global circulation and day-to-night heat transport as a function of irradiation, rotation rate, and internal heat.
An all-magnetic logic scheme has the advantages of being non-volatile and energy efficient over the conventional transistor based logic devices. In this work, we present a reconfigurable magnetic ...logic device which is capable of performing all basic logic operations in a single device. The device exploits the deterministic trajectory of domain wall (DW) in ferromagnetic asymmetric branch structure for obtaining different output combinations. The programmability of the device is achieved by using a current-controlled magnetic gate, which generates a local Oersted field. The field generated at the magnetic gate influences the trajectory of the DW within the structure by exploiting its inherent transverse charge distribution. DW transformation from vortex to transverse configuration close to the output branch plays a pivotal role in governing the DW chirality and hence the output. By simply switching the current direction through the magnetic gate, two universal logic gate functionalities can be obtained in this device. Using magnetic force microscopy imaging and magnetoresistance measurements, all basic logic functionalities are demonstrated.
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