79 research outputs found
Laser-induced Precession of Magnetization in GaMnAs
We report on the photo-induced precession of the ferromagnetically coupled Mn
spins in (Ga,Mn)As, which is observed even with no external magnetic field
applied. We concentrate on various experimental aspects of the time-resolved
magneto-optical Kerr effect (TR-MOKE) technique that can be used to clarify the
origin of the detected signals. We show that the measured data typically
consist of several different contributions, among which only the oscillatory
signal is directly connected with the ferromagnetic order in the sample.Comment: 4 pages, 5 figure
Super-resolution provided by the arbitrarily strong superlinearity of the blackbody radiation
Blackbody radiation is a fundamental phenomenon in nature, and its explanation by Planck marks a cornerstone in the history of Physics. In this theoretical work, we show that the spectral radiance given by Planck's law is strongly superlinear with temperature, with an arbitrarily large local exponent for decreasing wavelengths. From that scaling analysis, we propose a new concept of super-resolved detection and imaging: if a focused beam of energy is scanned over an object that absorbs and linearly converts that energy into heat, a highly nonlinear thermal radiation response is generated, and its point spread function can be made arbitrarily smaller than the excitation beam focus. Based on a few practical scenarios, we propose to extend the notion of super-resolution beyond its current niche in microscopy to various kinds of excitation beams, a wide range of spatial scales, and a broader diversity of target objects
Light-induced magnetization precession in GaMnAs
We report dynamics of the transient polar Kerr rotation (KR) and of the
transient reflectivity induced by femtosecond laser pulses in ferromagnetic
(Ga,Mn)As with no external magnetic field applied. It is shown that the
measured KR signal consist of several different contributions, among which only
the oscillatory signal is directly connected with the ferromagnetic order in
(Ga,Mn)As. The origin of the light-induced magnetization precession is
discussed and the magnetization precession damping (Gilbert damping) is found
to be strongly influenced by annealing of the sample.Comment: 6 pages, 4 figures. accepted in Applied Physics Letter
Picosecond transfer from short-term to long-term memory in analog antiferromagnetic memory device
Experiments in materials with a compensated ordering of magnetic moments have
demonstrated a potential for approaching the thermodynamic limit of the fastest
and least-dissipative operation of a digital memory bit. In addition, these
materials are very promising for a construction of energy-efficient analog
devices with neuromorphic functionalities, which are inspired by
computing-in-memory capabilities of the human brain. In this paper, we report
on experimental separation of switching-related and heat-related resistance
signal dynamics in memory devices microfabricated from CuMnAs antiferromagnetic
metal. We show that the memory variable multilevel resistance can be used as a
long-term memory (LTM), lasting up to minutes at room temperature. In addition,
ultrafast reflectivity change and heat dissipation from nanoscale-thickness
CuMnAs films, taking place on picosecond to hundreds of nanoseconds time
scales, can be used as a short-term memory (STM). Information about input
stimuli, represented by femtosecond laser pulses, can be transferred from STM
to LTM after rehearsals at picosecond to nanosecond times in these memory
devices, where information can be retrieved at times up to 10^15 longer than
the input pulse duration. Our results open a route towards ultra-fast low-power
implementations of spiking neuron and synapse functionalities using a resistive
analog antiferromagnetic memory.Comment: 21 pages, 4 figure
The effect of urban green spaces on house prices in Warsaw
In the paper, we analysed the impact of proximity to urban green areas on apartment prices in Warsaw. The data-set contained in 43 075 geo-coded apartment transactions for the years 2010 to 2015. In this research, the hedonic method was used in Ordinary Least Squares (OLS), Weighted Least Squares (WLS) and Median Quantile Regression (Median QR) models. We found substantial evidence that proximity to an urban green area is positively linked with apartment prices. On an average presence of a green area within 100 meters from an apartment increases the price of a dwelling by 2,8% to 3,1%. The effect of park/forest proximity on house prices is more significant for newer apartments than those built before 1989. We found that proximity to a park or a forest is particularly important (and has a higher implicit price as a result) in the case of buildings constructed after 1989. The impact of an urban green was particularly high in the case of a post-transformation housing estate. Close vicinity (less than 100 m distance) to an urban green increased the sales prices of apartments in new residential buildings by 8,0–8,6%, depending on a model
Inertial displacement of a domain wall excited by ultra-short circularly polarized laser pulses.
Domain wall motion driven by ultra-short laser pulses is a pre-requisite for envisaged low-power spintronics combining storage of information in magnetoelectronic devices with high speed and long distance transmission of information encoded in circularly polarized light. Here we demonstrate the conversion of the circular polarization of incident femtosecond laser pulses into inertial displacement of a domain wall in a ferromagnetic semiconductor. In our study, we combine electrical measurements and magneto-optical imaging of the domain wall displacement with micromagnetic simulations. The optical spin-transfer torque acts over a picosecond recombination time of the spin-polarized photo-carriers that only leads to a deformation of the initial domain wall structure. We show that subsequent depinning and micrometre-distance displacement without an applied magnetic field or any other external stimuli can only occur due to the inertia of the domain wall
Prevalence of JC Virus in Chinese Patients with Colorectal Cancer
BACKGROUND: JCV is a DNA polyomavirus very well adapted to humans. Although JCV DNA has been detected in colorectal cancers (CRC), the association between JCV and CRC remains controversial. In China, the presence of JCV infection in CRC patients has not been reported. Here, we investigated JCV infection and viral DNA load in Chinese CRC patients and to determine whether the JCV DNA in peripheral blood (PB) can be used as a diagnostic marker for JCV-related CRC. METHODOLOGY/PRINCIPAL FINDINGS: Tumor tissues, non-cancerous tumor-adjacent tissues and PB samples were collected from 137 CRC patients. In addition, 80 normal colorectal tissue samples from patients without CRC and PB samples from 100 healthy volunteers were also harvested as controls. JCV DNA was detected by nested PCR and glass slide-based dot blotting. Viral DNA load of positive samples were determined by quantitative real-time PCR. JCV DNA was detected in 40.9% (56/137) of CRC tissues at a viral load of 49.1 to 10.3×10(4) copies/µg DNA. Thirty-four (24.5%) non-cancerous colorectal tissues (192.9 to 4.4×10(3) copies/µg DNA) and 25 (18.2%) PB samples (81.3 to 4.9×10(3) copies/µg DNA) from CRC patients were positive for JCV. Tumor tissues had higher levels of JCV than non-cancerous tissues (P = 0.003) or PB samples (P<0.001). No correlation between the presence of JCV and demographic or medical characteristics was observed. The JCV prevalence in PB samples was significantly associated with the JCV status in tissue samples (P<0.001). Eleven (13.8%) normal colorectal tissues and seven (7.0%) PB samples from healthy donors were positive for JCV. CONCLUSIONS/SIGNIFICANCE: JCV infection is frequently present in colorectal tumor tissues of CRC patients. Although the association between JCV presence in PB samples and JCV status in tissue samples was identified in this study, whether PB JCV detection can serve as a marker for JCV status of CRC requires further study
Hypoxic Epithelial Necrosis Triggers Neutrophilic Inflammation via IL-1 Receptor Signaling in Cystic Fibrosis Lung Disease
Rationale: In many organs, hypoxic cell death triggers sterile neutrophilic inflammation via IL-1R signaling. Although hypoxia is common in airways from patients with cystic fibrosis (CF), its role in neutrophilic inflammation remains unknown. We recently demonstrated that hypoxic epithelial necrosis caused by airway mucus obstruction precedes neutrophilic inflammation in Scnn1b-transgenic (Scnn1b-Tg) mice with CF-like lung disease
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