Detection of the evolutionary stages of variables in M3

The large number of variables in M3 provides a unique opportunity to study an extensive sample of variables with the same apparent distance modulus. Recent, high accuracy CCD time series of the variables show that according to their mean magnitudes and light curve shapes, the variables belong to four separate groups. Comparing the properties of these groups (magnitudes and periods) with horizontal branch evolutionary models, we conclude that these samples can be unambiguously identified with different stages of the horizontal branch stellar evolution. Stars close to the zero age horizontal branch (ZAHB) show Oosterhoff I type properties, while the brightest stars have Oosterhoff II type statistics regarding their mean periods and RRab/RRc number ratios. This finding strengthens the earlier suggestion of Lee et al. (1990) connecting the Oosterhoff dichotomy to evolutionary effects, however, it is unexpected to find large samples of both of the Oosterhoff type within a single cluster, which is, moreover, the prototype of the Oosterhoff I class globular clusters. The very slight difference between the Fourier parameters of the stars (at a given period) in the three fainter samples spanning over about 0.15 mag range in M_V points to the limitations of any empirical methods which aim to determine accurate absolute magnitudes of RR Lyrae stars solely from the Fourier parameters of the light curves.Comment: 4 pages, 4 figures. Submitted to Astrophys. J. Letter

Integrin α_IIbβ₃ activation and clustering in minimal synthetic cells

Platelet adhesion and activation are mediated by integrin αIIbβ3 clustering, which is crucial for the hemostatic function of platelets. In an activated state, integrins provide the connection between the extracellular matrix and the actin cytoskeleton through a variety of cytoplasmic proteins, such as talin. Here, droplet-based microfluidics is applied to generate cell-sized giant unilamellar vesicles (GUVs) with a defined molecular composition to quantify the adhesion of integrin αIIbβ3-containing protocells in relation to the number of integrin–talin head domain (THD) complexes. Furthermore, it is shown that THD induces integrin clustering in protocells adhering to fibrinogen. The formation of this molecular link, which has, so far, only been observed in vivo, is an essential step in synthetic cell design to recapitulate integrin-mediated bidirectional signaling across the membrane. These results pave the way for further quantitative investigations of protein–protein interactions between integrins and associated proteins and their assembly within such defined, but complex, synthetic cells. An essential future step to mimic the complex interaction between cells and their environment will be to combine synthetic approaches with peptide chemistry to guide the molecular mechanisms involved in integrin binding and activation

Short-Term Forecasting of GDP Using Large Monthly Datasets: A Pseudo Real-Time Forecast Evaluation Exercise

This paper evaluates different models for the short-term forecasting of real GDP growth in ten selected European countries and the euro area as a whole. Purely quarterly models are compared with models designed to exploit early releases of monthly indicators for the nowcast and forecast of quarterly GDP growth. Amongst the latter, we consider small bridge equations and forecast equations in which the bridging between monthly and quarterly data is achieved through a regression on factors extracted from large monthly datasets. The forecasting exercise is performed in a simulated real-time context, which takes account of publication lags in the individual series. In general, we find that models that exploit monthly information outperform models that use purely quarterly data and, amongst the former, factor models perform best.Bridge models, Dynamic factor models, real-time data flow model

Short-term forecasting of GDP using large monthly datasets: a pseudo real-time forecast evaluation exercise.

This paper evaluates different models for the short-term forecasting of real GDP growth in ten selected European countries and the euro area as a whole. Purely quarterly models are compared with models designed to exploit early releases of monthly indicators for the nowcast and forecast of quarterly GDP growth. Amongst the latter, we consider small bridge equations and forecast equations in which the bridging between monthly and quarterly data is achieved through a regression on factors extracted from large monthly datasets. The forecasting exercise is performed in a simulated real-time context, which takes account of publication lags in the individual series. In general, we find that models that exploit monthly information outperform models that use purely quarterly data and, amongst the former, factor models perform best.Bridge models ; Dynamic factor models ; real-time data flow.

Towards Full Field-of-View Fourier Ptychography for Extreme Ultraviolet Microscope

We evaluate various Fourier ptychographic microscopy (FPM) reconstruction algorithms using both simulated and experimental data acquired from an Extreme Ultraviolet (EUV, 13.5 nm wavelength) microscope. We specifically focus on the algorithms' ability to robustly address field-dependent aberrations, which enables increased spatial resolution and quantitative phase imaging across an expanded field of view. We systematically compare the algorithms' performance under aberrations for a single zoneplate imaging system, utilizing Fourier Ring Correlation (FRC) as a systematic metric for assessing reconstruction quality. Furthermore, we explore the impact of systematic errors on the reconstruction of experimental data, aiming to increase the effective field of view by 25-fold, from the nominal 5x5 um2 diffraction-limited area. Additionally, our evaluation incorporates innovative FPM-adjacent methodologies, including the Angular Ptychographic Imaging with Closed-form method (APIC), for reconstructing EUV images

Lignin Dimers as Potential Markers for 14C-young Terrestrial Dissolved Organic Matter in the Critical Zone

The origin, molecular composition and fate of dissolved organic matter (DOM) provides essential information that links surface and subsurface processes and explores the functioning of the Critical Zone. Therefore it is important to identify specific marker compounds that provide information on the temporal and spatial linkages in the Critical Zone. Here, we used ultra-high resolution mass spectrometry and accelerator mass spectrometry in order to identify markers for fast transport of surface-derived DOM through the Critical Zone. We assessed the molecular composition and radiocarbon age of solid phase extracted DOM (SPE-DOM) from forest top soils. The 14C ages of SPE-DOM in our study were similar to that of bulk DOM. Calibrated ages ranged from 0 to 49 years and the within-site variability was larger than between sampling sites. Spearman rank correlation between the 14C ages and the DOM composition identified 129 sum formulae that were significantly correlated to 14C age. We found that molecular entities with younger 14C ages had lower molecular weight, higher unsaturation and less oxygen and heteroatoms than those associated with older 14C ages. A chemical library search suggested that phenylpropanoids and compounds, which are known to be lignin derived, are key molecular species for terrestrial DOM with young 14C ages. Among them, lignin dimers emerged as prominent surface-derived compounds that can potentially be used as markers for fast transport of water and DOM into the subsurface and groundwater

Большие числа П. Дирака и альтернативный анализ

Soft x-ray microscopy is well suited to investigation of nanoparticles in liquid media. Using a table-top microscope based on a gas-discharge source emitting at 2.88 nm, dried CdTe nanowires and dried PbS hyperbranched nanocrystals are investigated. These structures are the result of the assembly of nanoparticles in a liquid environment. Soft x-ray microscopy is aiming at a better understanding of underlying parameters that affect the self assembly to the desired final structures. It is shown that the presented setup is able to image these particles with a resolution of about 50 nm with exposure times in the range of tens of seconds. The discharge source has a photon flux of more than 109photons/(srsm2) at a photon energy of 430 eV with a bandwidth of /=840. The repetition rate of the source is up to 1000 Hz. With the current setup a photon flux of 5×10 6photons/(m2s) at the sample is achieved

Natural formation of chloro- and bromoacetone in salt lakes of Western Australia

Western Australia is a semi-/arid region known for saline lakes with a wide range of geochemical parameters (pH 2.5-7.1, Cl- 10-200 g L-1. This study reports on the haloacetones chloro- and bromoacetone in air over 6 salt lake shorelines. Significant emissions of chloroacetone (up to 0.2 µmol m-2 h-1) and bromoacetone (up to 1. 5 µmol m-2 h-1) were detected, and a photochemical box model was employed to evaluate the contribution of their atmospheric formation from the olefinic hydrocarbons propene and methacrolein in the gas phase. The measured concentrations could not explain the photochemical halogenation reaction, indicating a strong hitherto unknown source of haloacetones. Aqueous-phase reactions of haloacetones, investigated in the laboratory using humic acid in concentrated salt solutions, were identified as alternative formation pathway by liquid-phase reactions, acid catalyzed enolization of ketones, and subsequent halogenation. In order to verify this mechanism, we made measurements of the Henry's law constants, rate constants for hydrolysis and nucleophilic exchange with chloride, UV-spectra and quantum yields for the photolysis of bromoacetone and 1,1-dibromoacetone in the aqueous phase. We suggest that heterogeneous processes induced by humic substances in the quasi-liquid layer of the salt crust, particle surfaces and the lake water are the predominating pathways for the formation of the observed haloacetones