2,192 research outputs found
Adsorbate Electric Fields on a Cryogenic Atom Chip
We investigate the behaviour of electric fields originating from adsorbates
deposited on a cryogenic atom chip as it is cooled from room temperature to
cryogenic temperature. Using Rydberg electromagnetically induced transparency
we measure the field strength versus distance from a 1 mm square of YBCO
patterned onto a YSZ chip substrate. We find a localized and stable dipole
field at room temperature and attribute it to a saturated layer of chemically
adsorbed rubidium atoms on the YBCO. As the chip is cooled towards 83 K we
observe a change in sign of the electric field as well as a transition from a
localized to a delocalized dipole density. We relate these changes to the onset
of physisorption on the chip surface when the van der Waals attraction
overcomes the thermal desorption mechanisms. Our findings suggest that, through
careful selection of substrate materials, it may be possible to reduce the
electric fields caused by atomic adsorption on chips, opening up experiments to
controlled Rydberg-surface coupling schemes.Comment: 5 pages, 4 figure
Trapped ion mobility spectrometry and PASEF enable in-depth lipidomics from minimal sample amounts
A comprehensive characterization of the lipidome from limited starting material remains very challenging. Here we report a high-sensitivity lipidomics workflow based on nanoflow liquid chromatography and trapped ion mobility spectrometry (TIMS). Taking advantage of parallel accumulation-serial fragmentation (PASEF), we fragment on average 15 precursors in each of 100 ms TIMS scans, while maintaining the full mobility resolution of co-eluting isomers. The acquisition speed of over 100 Hz allows us to obtain MS/MS spectra of the vast majority of isotope patterns. Analyzing 1 mu L of human plasma, PASEF increases the number of identified lipids more than three times over standard TIMS-MS/MS, achieving attomole sensitivity. Building on high intra- and inter-laboratory precision and accuracy of TIMS collisional cross sections (CCS), we compile 1856 lipid CCS values from plasma, liver and cancer cells. Our study establishes PASEF in lipid analysis and paves the way for sensitive, ion mobility-enhanced lipidomics in four dimensions
Textural and Microstructural Properties of Frozen Fish Mince as Affected by the Addition of Nonfish Proteins and Sorbitol
Changes in textural and microstructural properties of washed and unwashed frozen fish mince were studied as affected by the addition of non fish proteins (soy protein isolate, milk protein isolate, egg white, and wheat gluten at 2 , 4 or 6%) and 6% crystalline sorbitol. Soy and milk proteins and sorbitol reduced the hardness of frozen fish mince, while egg white and wheat gluten made the texture firmer without rubberiness developing after frozen storage. All nonfish proteins and sorbitol stabilized the myofibrillar organization by reducing freeze-induced contraction of myofibrils.
The mechanisms of reducing texture hardening appear to be different between sorbitol and nonfish proteins. Water binding properties and dispersibility made the difference among nonfish proteins in reducing freeze-contraction of myofibrils. Nonfish proteins not only reduced texture hardening during frozen storage, but also modified texture during cooki ng as they underwent thermal gelation specific to each protein used
Composition of zooplankton assemblages along the Zagyva River
The species composition, longitudinal distribution and seasonal dynamics of zooplankton were
studied in the Zagyva River, Hungary. A total of 108 taxa was recorded from which 61 were new for the
river. Rotatoria was the most abundant group, microcrustaceans were less important, only nauplii and
copepodites were represented in similar individual numbers. Frequent species included Anuraeopsis fissa,
Pompholyx spp., Keratella cochlearis, Brachionus angularis, Bdelloida sp., Bosmina longirostris.
Dominance of cosmopolitan species was observed both in the river and its reservoir, and species
characteristic of eutrophic waters were of major importance in the latter. There was a downstream
decrease in zooplankton densities, which was explained by modified conditions. The relatively large
number of individuals in autumn months, and the characteristic large number of individuals in the upper
section contrasted general findings of potamoplankton dynamics. On the basis of the species abundance
matrix, three river sections can be distinguished (upper, middle, lower section). Due to waste water
discharges - received from the Tarján Stream - we found extremely high number of individuals and the
lowest diversity at the sampling site Nagybátony (148 rkm)
A new life for sterile neutrino dark matter after the pandemic
We propose a novel mechanism to generate sterile neutrinos in theearly Universe, by converting ordinary neutrinos in scatteringprocesses . After initial production byoscillations, this leads to an exponential growth in the abundance. Weshow that such a production regime naturally occurs for self-interacting, and that this opens up significant new parameter space where make up all of the observed dark matter. Our results provide strong motivationto further push the sensitivity of X-ray line searches, and to improve onconstraints from structure formation.<br
A new life for sterile neutrino dark matter after the pandemic
We propose a novel mechanism to generate sterile neutrinos in theearly Universe, by converting ordinary neutrinos in scatteringprocesses . After initial production byoscillations, this leads to an exponential growth in the abundance. Weshow that such a production regime naturally occurs for self-interacting, and that this opens up significant new parameter space where make up all of the observed dark matter. Our results provide strong motivationto further push the sensitivity of X-ray line searches, and to improve onconstraints from structure formation.<br
Cut mowing and grazing effects with grey cattle on plant species composition in case of Pannon wet grasslands
Examined area can be found at Balaton Uplands National Park (Hungary). 5 sample areas were
examined in Badacsonytördemic: 1: 32 hectare under-grazed pasture, 2: 38 hectare overgrazed pasture, 3:
34 hectare hayfield, 4: trampled area, 5: beaten track. Livestock population was 118 in the monitored
pastures. Sampling was executed along five 52m long circular transects, within 5cm × 5cm interlocking
quadrates. Based on the data we can state that the curve of the drinking area was the highest of speciesarea
examinations however weed appeared because of degradation which provided more species.
According to species-area examinations overgrazed areas were richer in species then other examined
areas. Based on diversity data drinking area considered degraded, while meadow and overgrazed areas
was considered as proper state. Diversity of meadow was larger, but dominance of economically useful
species was smaller. The amount of less valuable species – Carex hirta – increased
A new life for sterile neutrino dark matter after the pandemic
We propose a novel mechanism to generate sterile neutrinos in the early Universe, by converting ordinary neutrinos in scattering processes . After initial production by oscillations, this leads to an exponential growth in the abundance. We show that such a production regime naturally occurs for self-interacting , and that this opens up significant new parameter space where make up all of the observed dark matter. Our results provide strong motivation to further push the sensitivity of X-ray line searches, and to improve on constraints from structure formation
Mechanical Stress Inference for Two Dimensional Cell Arrays
Many morphogenetic processes involve mechanical rearrangement of epithelial
tissues that is driven by precisely regulated cytoskeletal forces and cell
adhesion. The mechanical state of the cell and intercellular adhesion are not
only the targets of regulation, but are themselves likely signals that
coordinate developmental process. Yet, because it is difficult to directly
measure mechanical stress {\it in vivo} on sub-cellular scale, little is
understood about the role of mechanics of development. Here we present an
alternative approach which takes advantage of the recent progress in live
imaging of morphogenetic processes and uses computational analysis of high
resolution images of epithelial tissues to infer relative magnitude of forces
acting within and between cells. We model intracellular stress in terms of bulk
pressure and interfacial tension, allowing these parameters to vary from cell
to cell and from interface to interface. Assuming that epithelial cell layers
are close to mechanical equilibrium, we use the observed geometry of the two
dimensional cell array to infer interfacial tensions and intracellular
pressures. Here we present the mathematical formulation of the proposed
Mechanical Inverse method and apply it to the analysis of epithelial cell
layers observed at the onset of ventral furrow formation in the {\it
Drosophila} embryo and in the process of hair-cell determination in the avian
cochlea. The analysis reveals mechanical anisotropy in the former process and
mechanical heterogeneity, correlated with cell differentiation, in the latter
process. The method opens a way for quantitative and detailed experimental
tests of models of cell and tissue mechanics
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