Individual skyrmion manipulation by local magnetic field gradients

Magnetic skyrmions are topologically protected spin textures, stabilised in systems with strong Dzyaloshinskii-Moriya interaction (DMI). Several studies have shown that electrical currents can move skyrmions efficiently through spin-orbit torques. While promising for technological applications, current-driven skyrmion motion is intrinsically collective and accompanied by undesired heating effects. Here we demonstrate a new approach to control individual skyrmion positions precisely, which relies on the magnetic interaction between sample and a magnetic force microscopy (MFM) probe. We investigate perpendicularly magnetised X/CoFeB/MgO multilayers, where for X = W or Pt the DMI is sufficiently strong to allow for skyrmion nucleation in an applied field. We show that these skyrmions can be manipulated individually through the local field gradient generated by the scanning MFM probe with an unprecedented level of accuracy. Furthermore, we show that the probe stray field can assist skyrmion nucleation. Our proof-of-concepts results pave the way towards achieving current-free skyrmion control

Mat á alvarleika persónuleikavandamála : athugun á spurningalistanum Severity Indices of Personality Problems (SIPP) í úrtaki íslenskra háskólanema

Neðst á síðunni er hægt að nálgast greinina í heild sinni með því að smella á hlekkinn View/OpenSpurningalistinn Severity Indices of Personality Problems eða SIPP er nýr spurningalisti sem metur alvarleika vandamála sem oft tengjast persónuleikaröskunum. Listinn er til í tveimur útgáfum og inniheldur önnur 118 atriði (SIPP- 118) sem skiptast á alls 16 undirþætti sem tilheyra fimm yfirþáttum. Hin útgáfan er styttri og inniheldur 60 atriði (SIPP-60) sem notuð eru til að reikna út skor þátttakenda á yfirþáttunum fimm. Tilgangur þessarar rannsóknar var að kanna próffræðilega eiginleika íslenskrar þýðingar á SIPP listunum í úrtaki 634 háskólanema. Niðurstöður sýndu að áreiðanleiki 13 af 16 undirþáttum SIPP-118 var ásættanlegur eða góður ( 0,70). Í leitandi þátttagreiningu voru þrír af fimm þáttum sambærilegir við niðurstöður erlendrar rannsóknar á SIPP-118. Skor á yfirþáttum SIPP-60 höfðu miðlungs til sterka fylgni við skor á spurningalista um lífsánægju þannig að meiri alvarleiki persónuleikavanamála tengdist minni lífsánægju. Marktækur munur var á meðaltölum á öllum yfirþáttum SIPP-60 milli hópa sem höfðu lág, miðlungs eða há skor á skimunarlista fyrir persónuleikaraskanir. Fyrstu niðurstöður á íslenskri þýðingu SIPP spurningalistans benda til að próffræðilegir eiginleikar listans séu góðir en kanna þarf betur þátttabyggingu listans. Áframhaldandi rannsóknir ættu einnig að beinast að notagildi listans við greiningu og mat á árangri meðferðar við persónuleikaröskunum

Pollen exposure is associated with risk of respiratory symptoms during the first year of life

BACKGROUND: Pollen exposure is associated with respiratory symptoms in children and adults. However, the association of pollen exposure with respiratory symptoms during infancy, a particularly vulnerable period, remains unclear. We examined whether pollen exposure is associated with respiratory symptoms in infants and whether maternal atopy, infant's sex or air pollution modifies this association. METHODS: We investigated 14,874 observations from 401 healthy infants of a prospective birth cohort. The association between pollen exposure and respiratory symptoms, assessed in weekly telephone interviews, was evaluated using generalized additive mixed models (GAMMs). Effect modification by maternal atopy, infant's sex, and air pollution (NO$_{2}$ , PM$_{2.5}$ ) was assessed with interaction terms. RESULTS: Per infant, 37 ± 2 (mean ± SD) respiratory symptom scores were assessed during the analysis period (January through September). Pollen exposure was associated with increased respiratory symptoms during the daytime (RR [95% CI] per 10% pollen/m$^{3}$ : combined 1.006 [1.002, 1.009]; tree 1.005 [1.002, 1.008]; grass 1.009 [1.000, 1.23]) and nighttime (combined 1.003 [0.999, 1.007]; tree 1.003 [0.999, 1.007]; grass 1.014 [1.004, 1.024]). While there was no effect modification by maternal atopy and infant's sex, a complex crossover interaction between combined pollen and PM$_{2.5}$ was found (p-value 0.003). CONCLUSION: Even as early as during the first year of life, pollen exposure was associated with an increased risk of respiratory symptoms, independent of maternal atopy and infant's sex. Because infancy is a particularly vulnerable period for lung development, the identified adverse effect of pollen exposure may be relevant for the evolvement of chronic childhood asthma

Is there an association between social determinants and care dependency risk? A multi‐state model analysis of a longitudinal study

Despite a growing body of knowledge about the morbidities and functional impairment that frequently lead to care dependency, the role of social determinants is not yet well understood. The purpose of this study was to examine the effect of social determinants on care dependency onset and progression. We used data from the Berlin Initiative Study, a prospective, population-based cohort study including 2,069 older participants living in Berlin. Care dependency was defined as requiring substantial assistance in at least two activities of daily living for 90 min daily (level 1) or 3+ hours daily (level 2). Multi-state time to event regression modeling was used to estimate the effects of social determinants (partnership status, education, income, and sex), morbidities, and health behaviors, characteristics, and conditions. During the study period, 556 participants (27.5%) changed their status of care dependency. Participants without a partner at baseline were at a higher risk to become care-dependent than participants with a partner (hazard ratio [HR], 95% confidence interval [CI]: 1.24 (1.02-1.51)). After adjustment for other social determinants, morbidities and health behaviors, characteristics, and conditions the risk decreased to a HR of 1.19 (95% CI: 0.79-1.79). Results indicate that older people without a partner may tend to be at higher risk of care dependency onset but not at higher risk of care dependency progression. Clinicians should inquire about and consider patients' partnership status as they evaluate care needs

Seasonality in bacterial diversity in north-west Mediterranean coastal waters: assessment through clone libraries, fingerprinting and FISH

We combined denaturing gradient gel electrophoresis (DGGE), catalysed reporter deposition-FISH (CARD-FISH) and clone libraries to investigate the seasonality of the bacterial assemblage composition in north-west Mediterranean coastal waters. DGGE analysis indicated that bacterial diversity changed gradually throughout the year, although with a clear distinction of the summer period. Alphaproteobacteria were the dominant group on an annual basis [29% of the DAPI (4′,6-diamidino-2-phenylindole) counts by CARD-FISH, and 70% of the bacterial clones]. The SAR11 clade was most abundant during spring and summer (>20% of DAPI counts), while the Roseobacter clade was abundant primarily in winter and spring (up to 7% of DAPI counts). The phylum Bacteroidetes constituted the second most important group and was quantitatively uniform throughout the year (average 11% of the DAPI counts). Gammaproteobacteria showed a peak during summer (8% of DAPI counts), when most of them belonged to the NOR5 cluster. Clone libraries and CARD-FISH showed reasonable agreement in the quantitative proportions of Bacteroidetes and Gammaproteobacteria, but Alphaproteobacteria were overrepresented in clone libraries. Sequencing of the most predominant DGGE bands failed to detect the SAR11 group despite their high abundance. The combination of the three molecular approaches allowed a comprehensive assessment of seasonal changes in bacterial diversit

Fast Predictions of Lattice Energies by Continuous Isometry Invariants of Crystal Structures

Crystal Structure Prediction (CSP) aims to discover solid crystalline materials by optimizing periodic arrangements of atoms, ions or molecules. CSP takes weeks of supercomputer time because of slow energy minimizations for millions of simulated crystals. The lattice energy is a key physical property, which hints at thermodynamic stability of a crystal but has no simple analytic expression. Past machine learning approaches to predict the lattice energy used slow crystal descriptors depending on manually chosen parameters. The new area of Periodic Geometry offers much faster isometry invariants that are also continuous under perturbations of atoms. Our experiments on simulated crystals confirm that a small distance between the new invariants guarantees a small difference of energies. We compare several kernel methods for invariant-based predictions of energy and achieve the mean absolute error of less than 5 kJ/mole or 0.05 eV/atom on a dataset of 5679 crystals

Tocotrienol Affects Oxidative Stress, Cholesterol Homeostasis and the Amyloidogenic Pathway in Neuroblastoma Cells: Consequences for Alzheimer’s Disease

One of the characteristics of Alzheimer´s disease (AD) is an increased amyloid load and an enhanced level of reactive oxidative species (ROS). Vitamin E has known beneficial neuroprotective effects, and previously, some studies suggested that vitamin E is associated with a reduced risk of AD due to its antioxidative properties. However, epidemiological studies and nutritional approaches of vitamin E treatment are controversial. Here, we investigate the effect of α-tocotrienol, which belongs to the group of vitamin E, on AD-relevant processes in neuronal cell lines. In line with the literature, α-tocotrienol reduced the ROS level in SH-SY5Y cells. In the presence of tocotrienols, cholesterol and cholesterol esters, which have been shown to be risk factors in AD, were decreased. Besides the unambiguous positive effects of tocotrienol, amyloid-β (Aβ) levels were increased accompanied by an increase in the activity of enzymes responsible for Aβ production. Proteins and gene expression of the secretases and their components remained unchanged, whereas tocotrienol accelerates enzyme activity in cell-free assays. Besides enhanced Aβ production, tocotrienols inhibited Aβ degradation in neuro 2a (N2a)-cells. Our results might help to understand the controversial findings of vitamin E studies and demonstrate that besides the known positive neuroprotective properties, tocotrienols also have negative characteristics with respect to AD

Differences in autophagy marker levels at birth in preterm vs. term infants.

BACKGROUND Preterm infants are susceptible to oxidative stress and prone to respiratory diseases. Autophagy is an important defense mechanism against oxidative-stress-induced cell damage and involved in lung development and respiratory morbidity. We hypothesized that autophagy marker levels differ between preterm and term infants. METHODS In the prospective Basel-Bern Infant Lung Development (BILD) birth cohort we compared cord blood levels of macroautophagy (Beclin-1, LC3B), selective autophagy (p62) and regulation of autophagy (SIRT1) in 64 preterm and 453 term infants. RESULTS Beclin-1 and LC3B did not differ between preterm and term infants. However, p62 was higher (0.37, 95% confidence interval (CI) 0.05;0.69 in log2-transformed level, p = 0.025, padj = 0.050) and SIRT1 lower in preterm infants (-0.55, 95% CI -0.78;-0.31 in log2-transformed level, padj < 0.001). Furthermore, p62 decreased (padj-value for smoothing function was 0.018) and SIRT1 increased (0.10, 95% CI 0.07;0.13 in log2-transformed level, padj < 0.001) with increasing gestational age. CONCLUSION Our findings suggest differential levels of key autophagy markers between preterm and term infants. This adds to the knowledge of the sparsely studied field of autophagy mechanisms in preterm infants and might be linked to impaired oxidative stress response, preterm birth, impaired lung development and higher susceptibility to respiratory morbidity in preterm infants. IMPACT To the best of our knowledge, this is the first study to investigate autophagy marker levels between human preterm and term infants in a large population-based sample in cord blood plasma This study demonstrates differential levels of key autophagy markers in preterm compared to term infants and an association with gestational age This may be linked to impaired oxidative stress response or developmental aspects and provide bases for future studies investigating the association with respiratory morbidity

Vitamin D and Its Analogues Decrease Amyloid-β (Aβ) Formation and Increase Aβ-Degradation

Alzheimer’s disease (AD) is characterized by extracellular plaques in the brain, mainly consisting of amyloid-β (Aβ), as derived from sequential cleavage of the amyloid precursor protein. Epidemiological studies suggest a tight link between hypovitaminosis of the secosteroid vitamin D and AD. Besides decreased vitamin D level in AD patients, an effect of vitamin D on Aβ-homeostasis is discussed. However, the exact underlying mechanisms remain to be elucidated and nothing is known about the potential effect of vitamin D analogues. Here we systematically investigate the effect of vitamin D and therapeutically used analogues (maxacalcitol, calcipotriol, alfacalcidol, paricalcitol, doxercalciferol) on AD-relevant mechanisms. D2 and D3 analogues decreased Aβ-production and increased Aβ-degradation in neuroblastoma cells or vitamin D deficient mouse brains. Effects were mediated by affecting the Aβ-producing enzymes BACE1 and γ-secretase. A reduced secretase activity was accompanied by a decreased BACE1 protein level and nicastrin expression, an essential component of the γ-secretase. Vitamin D and analogues decreased β-secretase activity, not only in mouse brains with mild vitamin D hypovitaminosis, but also in non-deficient mouse brains. Our results further strengthen the link between AD and vitamin D, suggesting that supplementation of vitamin D or vitamin D analogues might have beneficial effects in AD prevention