Influence of MgO overlayers on the electronic states of bct Co(001) thin film grown on bcc Fe(001)/GaAs(001

The spin polarization of the valence band electronic states of strained bcc Co(001) and MgO/Co(001) thin films grown onto a bcc Fe(001) seed layer on GaAs(001) are investigated by employing spin-resolved photoemission spectroscopy. The experimental results are compared with the calculated energy band structure of bcc and bct Co(001), and discussed in the framework of the interband transition model, which allows one to ascribe the observed spectral features to bands of given spin and spatial symmetry. In contrast to the positive spin polarization observed at the MgO/Fe(001) interface, a large negative spin polarization of the electronic states at the Fermi level is observed for the MgO/Co/Fe/GaAs(001) system. Such a large negative spin polarization is attributed to a change in the energy band structure at the bct Co/bcc Fe(001) interface

Kinetic models with randomly perturbed binary collisions

We introduce a class of Kac-like kinetic equations on the real line, with general random collisional rules, which include as particular cases models for wealth redistribution in an agent-based market or models for granular gases with a background heat bath. Conditions on these collisional rules which guarantee both the existence and uniqueness of equilibrium profiles and their main properties are found. We show that the characterization of these stationary solutions is of independent interest, since the same profiles are shown to be solutions of different evolution problems, both in the econophysics context and in the kinetic theory of rarefied gases

Potent inhibitory activity of chimeric oligonucleotides targeting two different sites of human telomerase

Suppression of telomerase activity in tumor cells has been considered as a new anticancer strategy. Here, we present chimeric oligonucleotides (chimeric ODNs) as a new type of telomerase inhibitor that contains differently modified oligomers to address two different sites of telomerase: the RNA template and a suggested protein motif. We have shown previously that phosphorothioate-modified oligonucleotides (PS ODNs) interact in a length-dependent rather than in a sequence-dependent manner, presumably with the protein part of the primer-binding site of telomerase, causing strong inhibition of telomerase. In the present study, we demonstrate that extensions of these PS ODNs at their 3'-ends with an antisense oligomer partial sequence covering 11 bases of the RNA template cause significantly increased inhibitory activity, with IC(50) values between 0.60 and 0.95 nM in a Telomeric Repeat Amplification Protocol (TRAP) assay based on U-87 cell lysates. The enhanced inhibitory activity is observed regardless of whether the antisense part is modified (phosphodiester, PO; 2'-O-methylribosyl, 2'-OMe/PO; phosphoramidate, PAM). However, inside intact U-87 cells, these modifications of the antisense part proved to be essential for efficient telomerase inhibition 20 hours after transfection. In particular, the chimeric ODNs containing PAM or 2'-OMe/PO modifications, when complexed with lipofectin, were most efficient telomerase inhibitors (ID(50) = 0.04 and 0.06 microM, respectively). In conclusion, ODNs of this new type emerged as powerful inhibitors of human telomerase and are, therefore, promising candidates for further investigations of the anticancer strategy of telomerase inhibition

The representation of solar cycle signals in stratospheric ozone – Part 1: A comparison of satellite observations

Changes in incoming solar ultraviolet radiation over the 11-year solar cycle affect stratospheric ozone abundances. It is important to quantify the magnitude, structure, and seasonality of the associated solar-ozone response (SOR) to understand the impact of the 11-year solar cycle on climate. Part 1 of this two-part study uses multiple linear regression analysis to extract the SOR in a number of recently updated satellite ozone datasets covering different periods within the epoch 1970 to 2013. The annual mean SOR in the updated version 7.0 (v7.0) Stratospheric Aerosol and Gas Experiment (SAGE) II number density dataset (1984–2004) is very consistent with that found in the previous v6.2. In contrast, we find a substantial decrease in the magnitude of the SOR in the tropical upper stratosphere in the SAGE II v7.0 mixing ratio dataset (∼ 1 %) compared to the v6.2 (∼ 4 %). This difference is shown to be largely attributable to the change in the independent stratospheric temperature dataset used to convert SAGE II ozone number densities to mixing ratios. Since these temperature records contain substantial uncertainties, we suggest that datasets based on SAGE II number densities are currently most reliable for evaluating the SOR. We further analyse three extended ozone datasets that combine SAGE II v7.0 number densities with more recent GOMOS (Global Ozone Monitoring by Occultation of Stars) or OSIRIS (Optical Spectrograph and Infrared Imager System) measurements. The extended SAGE–OSIRIS dataset (1984–2013) shows a smaller and less statistically significant SOR across much of the tropical upper stratosphere compared to the SAGE II data alone. In contrast, the two SAGE–GOMOS datasets (1984–2011) show SORs that are in closer agreement with the original SAGE II data and therefore appear to provide a more reliable estimate of the SOR. We also analyse the SOR in the recent Solar Backscatter Ultraviolet Instrument (SBUV) Merged Ozone Dataset (SBUVMOD) version 8.6 (VN8.6) (1970–2012) and SBUV Merged Cohesive VN8.6 (1978–2012) datasets and compare them to the previous SBUVMOD VN8.0 (1970–2009). Over their full lengths, the three records generally agree in terms of the broad magnitude and structure of the annual mean SOR. The main difference is that SBUVMOD VN8.6 shows a smaller and less significant SOR in the tropical upper stratosphere and therefore more closely resembles the SAGE II v7.0 mixing ratio data than does the SBUV Merged Cohesive VN8.6, which has a more continuous SOR of ∼ 2 % in this region. The sparse spatial and temporal sampling of limb satellite instruments prohibits the extraction of sub-annual variations in the SOR from SAGE-based datasets. However, the SBUVMOD VN8.6 dataset suggests substantial month-to-month variations in the SOR, particularly in the winter extratropics, which may be important for the proposed high-latitude dynamical response to the solar cycle. Overall, the results highlight substantial uncertainties in the magnitude and structure of the observed SOR from different satellite records. The implications of these uncertainties for understanding and modelling the effects of solar variability on climate should be explored

The 3D structure of lipidic fibrils of alpha-synuclein

α-synuclein misfolding and aggregation into fibrils is a common feature of α-synucleinopathies, such as Parkinson’s disease, in which α-synuclein fibrils are a characteristic hallmark of neuronal inclusions called Lewy bodies. Studies on the composition of Lewy bodies extracted postmortem from brain tissue of Parkinson’s patients revealed that lipids and membranous organelles are also a significant component. Interactions between α-synuclein and lipids have been previously identified as relevant for Parkinson’s disease pathology, however molecular insights into their interactions have remained elusive. Here we present cryo-electron microscopy structures of six α-synuclein fibrils in complex with lipids, revealing specific lipid-fibril interactions. We observe that phospholipids promote an alternative protofilament fold, mediate an unusual arrangement of protofilaments, and fill the central cavities of the fibrils. Together with our previous studies, these structures also indicate a mechanism for fibril-induced lipid extraction, which is likely to be involved in the development of α-synucleinopathies. Specifically, one potential mechanism for the cellular toxicity is the disruption of intracellular vesicles mediated by fibrils and oligomers, and therefore the modulation of these interactions may provide a promising strategy for future therapeutic interventions

Content in fatty acids and carotenoids in phytoplankton blooms during the seasonal sea ice retreat in Hudson Bay complex, Canada.

The Hudson Bay complex (HBC) is home to numerous indigenous communities that traditionally have relied heavily on its marine resources. The nutritional quality and stocks of the entire HBC food web depend in large part on the phytoplankton production of bioactive molecules (long chain polyunsaturated fatty acids and carotenoids) and their transfer through trophic levels. The purpose of this study was thus to determine which molecules were produced during spring phytoplankton blooms, as well as the environmental factors driving this production. We investigated 21 stations in 5 sub-regions of the HBC. At the time of sampling, the sub-regions studied had different environmental settings (e.g., ice cover, nutrients, seawater salinity and temperature) conditioning their bloom stages. Pre- and post-bloom stages were associated with relatively low concentrations of bioactive molecules (either fatty acids or carotenoids). In contrast, the highest concentrations of bioactive molecules (dominated by eicosapentaenoic acid and fucoxanthin) were associated with the diatom bloom that typically occurs at the ice edge when silicates remain available. Interestingly, the large riverine inputs in eastern Hudson Bay led to a change in protist composition (larger contribution of Dinophyceae), resulting in lower while more diverse content of bioactive molecules, whether fatty acids (e.g., aa-linolenic acid) or carotenoids (e.g., peridinin). As greater stratification of the HBC is expected in the future, we suggest that a mixotrophic/heterotrophic flagellate-based food web would become more prevalent, resulting in a smaller supply of bioactive molecules for the food web

The role of body height as a co-factor of excess weight in Switzerland.

OBJECT Excess weight (Body Mass Index [BMI] ≥25.0 kg/m2 ) is a major health issue worldwide, including in Switzerland. For high-income countries, little attention has been paid to body height in context of excess weight. The aim of this study is to assess the importance of body height as a co-factor for excess weight in multiple large nationwide data sets. DATA AND METHODS In this comparative study, we included the largest nationwide and population-based studies in the fields of public health, nutrition and economics for Switzerland, as well as data of the medical examination during conscription for the Swiss Armed Forces, which contained information on BMI and, if possible, waist-to-height-ratio (WHtR) and waist-to-hip-ratio (WHR). RESULTS The multinomial logistic regressions show that the probability of belonging to the excess weight category (BMI ≥25.0 kg/m2 ) decreased with increasing height in both sexes inall contemporary data sets. This negative association was shown to be constant, only among conscripts measured in the 1870s the association was positive, when increasing height was associated with a higher BMI. The negative association not only emerge in BMI, but also in WHtR and WHR. CONCLUSION Our results emphasize the importance of body height as a co-factor of excess weight, suggesting a clear negative association between height and BMI, WHtR and WHR. Evidence indicates that both early-life environmental exposures and alleles associated with height may contribute to these associations. This knowledge could serve as further starting points for prevention programs in the field of public health

The role of body height as a co-factor of excess weight in Switzerland

OBJECT: Excess weight (Body Mass Index [BMI] ≥25.0 kg/m2 ) is a major health issue worldwide, including in Switzerland. For high-income countries, little attention has been paid to body height in context of excess weight. The aim of this study is to assess the importance of body height as a co-factor for excess weight in multiple large nationwide data sets. DATA AND METHODS: In this comparative study, we included the largest nationwide and population-based studies in the fields of public health, nutrition and economics for Switzerland, as well as data of the medical examination during conscription for the Swiss Armed Forces, which contained information on BMI and, if possible, waist-to-height-ratio (WHtR) and waist-to-hip-ratio (WHR). RESULTS: The multinomial logistic regressions show that the probability of belonging to the excess weight category (BMI ≥25.0 kg/m2 ) decreased with increasing height in both sexes inall contemporary data sets. This negative association was shown to be constant, only among conscripts measured in the 1870s the association was positive, when increasing height was associated with a higher BMI. The negative association not only emerge in BMI, but also in WHtR and WHR. CONCLUSION: Our results emphasize the importance of body height as a co-factor of excess weight, suggesting a clear negative association between height and BMI, WHtR and WHR. Evidence indicates that both early-life environmental exposures and alleles associated with height may contribute to these associations. This knowledge could serve as further starting points for prevention programs in the field of public health

Approximation of conformal mappings by circle patterns

A circle pattern is a configuration of circles in the plane whose combinatorics is given by a planar graph G such that to each vertex of G corresponds a circle. If two vertices are connected by an edge in G, the corresponding circles intersect with an intersection angle in $(0,\pi)$. Two sequences of circle patterns are employed to approximate a given conformal map $g$ and its first derivative. For the domain of $g$ we use embedded circle patterns where all circles have the same radius decreasing to 0 and which have uniformly bounded intersection angles. The image circle patterns have the same combinatorics and intersection angles and are determined from boundary conditions (radii or angles) according to the values of $g'$ ($|g'|$ or $\arg g'$). For quasicrystallic circle patterns the convergence result is strengthened to $C^\infty$-convergence on compact subsets.Comment: 36 pages, 7 figure