Multiferroics, where (anti-) ferromagnetic, ferroelectric and ferroelastic order parameters coexist, enable manipulation of magnetic ordering by an electric field through switching of the electric ...polarization. It has been shown that realization of magnetoelectric coupling in a single-phase multiferroic such as BiFeO3 requires ferroelastic (71 , 109 ) rather than ferroelectric (180 ) domain switching. However, the control of such ferroelastic switching in a single-phase system has been a significant challenge as elastic interactions tend to destabilize small switched volumes, resulting in subsequent ferroelastic back-switching at zero electric field, and thus the disappearance of non-volatile information storage. Guided by our phase-field simulations, here we report an approach to stabilize ferroelastic switching by eliminating the stress-induced instability responsible for back-switching using isolated monodomain BiFeO3 islands. This work demonstrates a critical step to control and use non-volatile magnetoelectric coupling at the nanoscale. Beyond magnetoelectric coupling, it provides a framework for exploring a route to control multiple order parameters coupled to ferroelastic order in other low-symmetry materials.
SN 2013dy is a Type Ia supernova (SN Ia) for which we have compiled an extraordinary data set spanning from 0.1 to ∼ 500 d after explosion. We present 10 epochs of ultraviolet (UV) through ...near-infrared (NIR) spectra with Hubble Space Telescope/Space Telescope Imaging Spectrograph, 47 epochs of optical spectra (15 of them having high resolution), and more than 500 photometric observations in the BVrRiIZYJH bands. SN 2013dy has a broad and slowly declining light curve (Δm
15(B) = 0.92 mag), shallow
$\mathrm{Si}\,\small {II}\,\lambda 6355$
absorption, and a low velocity gradient. We detect strong C ii in our earliest spectra, probing unburned progenitor material in the outermost layers of the SN ejecta, but this feature fades within a few days. The UV continuum of SN 2013dy, which is strongly affected by the metal abundance of the progenitor star, suggests that SN 2013dy had a relatively high-metallicity progenitor. Examining one of the largest single set of high-resolution spectra for an SN Ia, we find no evidence of variable absorption from circumstellar material. Combining our UV spectra, NIR photometry, and high-cadence optical photometry, we construct a bolometric light curve, showing that SN 2013dy had a maximum luminosity of
$10.0^{+4.8}_{-3.8} \times 10^{42}$
erg s−1. We compare the synthetic light curves and spectra of several models to SN 2013dy, finding that SN 2013dy is in good agreement with a solar-metallicity W7 model.
In patients with Parkinson's disease (PD), the associated pathology follows a characteristic pattern involving inter alia the enteric nervous system (ENS), the dorsal motor nucleus of the vagus ...(DMV), the intermediolateral nucleus of the spinal cord and the substantia nigra, providing the basis for the neuropathological staging of the disease. Here we report that intragastrically administered rotenone, a commonly used pesticide that inhibits Complex I of the mitochondrial respiratory chain, is able to reproduce PD pathological staging as found in patients. Our results show that low doses of chronically and intragastrically administered rotenone induce alpha-synuclein accumulation in all the above-mentioned nervous system structures of wild-type mice. Moreover, we also observed inflammation and alpha-synuclein phosphorylation in the ENS and DMV. HPLC analysis showed no rotenone levels in the systemic blood or the central nervous system (detection limit rotenone<20 nM) and mitochondrial Complex I measurements showed no systemic Complex I inhibition after 1.5 months of treatment. These alterations are sequential, appearing only in synaptically connected nervous structures, treatment time-dependent and accompanied by inflammatory signs and motor dysfunctions. These results strongly suggest that the local effect of pesticides on the ENS might be sufficient to induce PD-like progression and to reproduce the neuroanatomical and neurochemical features of PD staging. It provides new insight into how environmental factors could trigger PD and suggests a transsynaptic mechanism by which PD might spread throughout the central nervous system.
The formation of two-dimensional electron gases (2DEGs) at complex oxide interfaces is directly influenced by the oxide electronic properties. We investigated how local electron correlations control ...the 2DEG by inserting a single atomic layer of a rare-earth oxide (RO) (R is lanthanum (La), praseodymium (Pr), neodymium (Nd), samarium (Sm), or yttrium (Y) into an epitaxial strontium titanate oxide (SrTiO₃) matrix using pulsed-laser deposition with atomic layer control. We find that structures with La, Pr, and Nd ions result in conducting 2DEGs at the inserted layer, whereas the structures with Sm or Y ions are insulating. Our local spectroscopic and theoretical results indicate that the interfacial conductivity is dependent on electronic correlations that decay spatially into the SrTiO₃ matrix. Such correlation effects can lead to new functionalities in designed heterostructures.
The merging neutron star gravitational-wave event GW170817 has been observed throughout the entire electromagnetic spectrum from radio waves to γ-rays. The resulting energetics, variability, and ...light curves are shown to be consistent with GW170817 originating from the merger of two neutron stars, in all likelihood followed by the prompt gravitational collapse of the massive remnant. The available γ-ray, X-ray, and radio data provide a clear probe for the nature of the relativistic ejecta and the non-thermal processes occurring within, while the ultraviolet, optical, and infrared emission are shown to probe material torn during the merger and subsequently heated by the decay of freshly synthesized r-process material. The simplest hypothesis, that the non-thermal emission is due to a low-luminosity short γ-ray burst (sGRB), seems to agree with the present data. While low-luminosity sGRBs might be common, we show here that the collective prompt and multi-wavelength observations are also consistent with a typical, powerful sGRB seen off-axis. Detailed follow-up observations are thus essential before we can place stringent constraints on the nature of the relativistic ejecta in GW170817.
Leptin alleviates metabolic conditions such as insulin resistance and obesity, although the precise mechanism of action is unclear. Mitochondrial fusion/fission states affect energy balance, but the ...association between mitochondrial fusion and lipid metabolism is also unknown. The aim of this study was to determine whether mitochondrial fusion/fission state regulates lipid accumulation and to understand the role of leptin in mitochondrial function and its mechanism of action in metabolic regulation.
Primary mouse hepatocytes were isolated from C57BL/6J mice and treated with leptin (25 ng ml(-1)) for 3 days before determinations of mitochondrial morphology and fatty acid accumulation. Hyperglycemia in C57BL/6J mice was induced by providing a 30% fructose-rich diet (FRD) for 6 months, followed by intraperitoneal injections of leptin (1 mg kg(-1) per body weight) for 6 weeks (twice per week).
Leptin triggered mitochondrial fusion and alleviated high glucose-induced fatty acid accumulation in primary hepatocytes by promoting mitochondrial fusion-associated transcription factor peroxisome proliferative-activated receptor-α and co-activator peroxisome proliferative-activated receptor-γ co-activator (PGC)-1α. In turn, these activate the fusion protein mitofusin 1 (Mfn-1). RNA silencing of Mfn-1 or PGC-1 blocked the inhibitory effect of leptin. Leptin treatment also elevated liver Mfn-1 and PGC-1α and improved lipid profiles in FRD mice.
Mitochondrial fusion has a critical role in alleviating hepatic fatty acid accumulation. Leptin switches mitochondrial morphology via a PGC-1α-dependent pathway to improve hyperlipidemia.
We aimed to establish the prevalence, characteristics, and outcomes of intracranial atherosclerosis (ICAS) in China by a large, prospective, multicenter study.
We evaluated 2864 consecutive patients ...who experienced an acute cerebral ischemia<7 days after symptom onset in 22 Chinese hospitals. All patients underwent magnetic resonance angiography, with measurement of diameter of the main intracranial arteries. ICAS was defined as ≥50% diameter reduction on magnetic resonance angiography.
The prevalence of ICAS was 46.6% (1335 patients, including 261 patients with coexisting extracranial carotid stenosis). Patients with ICAS had more severe stroke at admission and stayed longer in hospitals compared with those without intracranial stenosis (median National Institutes of Health Stroke Scale score, 3 versus 5; median length of stay, 14 versus 16 days; both P<0.0001). After 12 months, recurrent stroke occurred in 3.27% of patients with no stenosis, in 3.82% for those with 50% to 69% stenosis, in 5.16% for those with 70% to 99% stenosis, and in 7.27% for those with total occlusion. Cox proportional hazards regression analyses showed that the degree of arterial stenosis, age, family history of stroke, history of cerebral ischemia or heart disease, complete circle of Willis, and National Institutes of Health Stroke Scale score at admission were independent predictors for recurrent stroke at 1 year. The highest rate of recurrence was observed in patients with occlusion with the presence of ≥3 additional risk factors.
ICAS is the most common vascular lesion in patients with cerebrovascular disease in China. Recurrent stroke rate in our study was lower compared with those of previous clinical trials but remains unacceptably high in a subgroup of patients with severe stenosis.
Because angiotensin-converting enzyme (ACE) activity is implicated widely in biological systems, we aimed to identify its novel quantitative trait loci for the purposes of understanding ACE activity ...regulation and pharmacogenetics relating to ACE inhibitor (ACEI). We performed a two-stage genome-wide association study: (1) from 400 young-onset hypertension (YOH) subjects and (2) a confirmation study with an additional 623 YOH subjects. In the first stage, eight single nucleotide polymorphisms (SNPs) of the ACE structural gene and one SNP of ABO genes were significantly associated with ACE activity. SNP rs4343 in exon17 near the well-known insertion/deletion polymorphism had the strongest association. We confirmed in the second stage that three SNPs: rs4343 in ACE gene (P=3.0 x 10⁻²⁵), rs495828 (P=3.5 x 10⁻⁸) and rs8176746 (P=9.3 x 10⁻⁵) in ABO gene were significantly associated with ACE activity. We further replicated the association between ABO genotype/blood types and ACE activity in an independent YOH family study (428 hypertension pedigrees), and showed a potential differential blood pressure response to ACEI in subjects with varied numbers of ACE-activity-raising alleles. These findings may broaden our understanding of the mechanisms controlling ACE activity and advance our pharmacogenetic knowledge on ACEI.
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