533 research outputs found
Modified Gravity Away from a CDM Background
Within the effective field theory approach to cosmic acceleration, the
background expansion can be specified separately from the gravitational
modifications. We explore the impact of modified gravity in a background
different from a cosmological constant plus cold dark matter (CDM) on
the stability and cosmological observables, including covariance between
gravity and expansion parameters. In No Slip Gravity the more general
background allows more gravitational freedom, including both positive and
negative Planck mass running. We examine the effects on cosmic structure
growth, as well as showing that a viable positive integrated Sachs-Wolfe effect
crosscorrelation easily arises from this modified gravity theory. Using current
data we constrain parameters with a Monte Carlo analysis, finding a maximum
running . We provide the modified {\tt hi\_class} code
publicly on GitHub, now enabling computation and inclusion of the redshift
space distortion observable as well as the No Slip Gravity
modifications.Comment: 14 pages, 13 figures. Matches published version in JCAP, LCDM
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Raman-spectroscopy based cell identification on a microhole array chip
Circulating tumor cells (CTCs) from blood of cancer patients are valuable prognostic markers and enable monitoring responses to therapy. The extremely low number of CTCs makes their isolation and characterization a major technological challenge. For label-free cell identification a novel combination of Raman spectroscopy with a microhole array platform is described that is expected to support high-throughput and multiplex analyses. Raman spectra were registered from regularly arranged cells on the chip with low background noise from the silicon nitride chip membrane. A classification model was trained to distinguish leukocytes from myeloblasts (OCI-AML3) and breast cancer cells (MCF-7 and BT-20). The model was validated by Raman spectra of a mixed cell population. The high spectral quality, low destructivity and high classification accuracy suggests that this approach is promising for Raman activated cell sorting
Structural analysis and corrosion studies on an ISO 5832-9 biomedical alloy with TiO2 sol–gel layers
The aim of this study was to demonstrate the
relationship between the structural and corrosion properties
of an ISO 5832-9 biomedical alloy modified with titanium
dioxide (TiO2) layers. These layers were obtained via the
sol–gel method by acid-catalyzed hydrolysis of titanium
isopropoxide in isopropanol solution. To obtain TiO2 layers
with different structural properties, the coated samples
were annealed at temperatures of 200, 300, 400, 450, 500,
600 and 800 C for 2 h. For all the prepared samples,
accelerated corrosion measurements were performed in
Tyrode’s physiological solution using electrochemical
methods. The most important corrosion parameters were
determined: corrosion potential, polarization resistance,
corrosion rate, breakdown and repassivation potentials.
Corrosion damage was analyzed using scanning electron
microscopy. Structural analysis was carried out for selected
TiO2 coatings annealed at 200, 400, 600 and 800 C. In
addition, the morphology, chemical composition, crystallinity,
thickness and density of the deposited TiO2 layers
were determined using suitable electron and X-ray measurement
methods. It was shown that the structure and
character of interactions between substrate and deposited
TiO2 layers depended on annealing temperature. All the
obtained TiO2 coatings exhibit anticorrosion properties, but
these properties are related to the crystalline structure and
character of substrate–layer interaction. From the point of
view of corrosion, the best TiO2 sol–gel coatings for stainless steel intended for biomedical applications seem to
be those obtained at 400 C.This study was supported by Grant No. N N507
501339 of the National Science Centre. The authors wish to express
their thanks to J. Borowski (MEDGAL, Poland) for the Rex 734 alloy
Design, Development, and In-flight Testing of a Pointer/tracker for In-flight Experiments to Measure Aero-optical Effects over a Scaled Turret
We address the design, development, and testing of a pointer/tracker as a probe beam for the purpose of making high-speed, aero-optical measurements of the flow over a scaled beam director turret. The tracker uses retro-reflection of the probe beam off of a Reflexite annulus surrounding the turret. The constraints of the design required a near-total-commercial off the shelf system that could be quickly installed and removed in a rented aircraft. Baseline measurements of environmental vibrations are used to predict pointing performance; mitigation of line-of-sight jitter on the probe beam is achieved through passive isolation and the design of relay optics. Accommodation of ambient light is made with the use of wavelength filters and track algorithms. Postanalysis of measured data is compared to design estimates
Effects of serum proteins on corrosion behavior of ISO 5832–9 alloy modified by titania coatings
Stainless steel ISO 5832–9 type is often used to
perform implants which operate in protein-containing physiological
environments. The interaction between proteins and
surface of the implant may affect its corrosive properties. The
aim of this work was to study the effect of selected serum
proteins (albumin and γ-globulins) on the corrosion of ISO
5832–9 alloy (trade name M30NW) which surface was modified
by titania coatings. These coatings were obtained by sol–
gel method and heated at temperatures of 400 and 800 °C. To
evaluate the effect of the proteins, the corrosion tests were
performed with and without the addition of proteins with
concentration of 1 g L−1 to the physiological saline solution
(0.9 % NaCl, pH 7.4) at 37 °C. The tests were carried out
within 7 days. The following electrochemical methods were
used: open circuit potential, linear polarization resistance, and
electrochemical impedance spectroscopy. In addition, surface
analysis by optical microscopy and X-ray photoelectron spectroscopy
(XPS) method was done at the end of weekly corrosion
tests. The results of corrosion tests showed that M30NW
alloy both uncoated and modified with titania coatings exhibits
a very good corrosion resistance during weekly exposition
to corrosion medium. The best corrosion resistance in
0.9 % NaCl solution is shown by alloy samples modified by
titania coating annealed at 400 °C. The serumproteins have no
significant effect onto corrosion of investigated biomedical
steel. The XPS results confirmed the presence of proteins on
the alloy surface after 7 days of immersion in proteincontaining
solutions.The investigations were supported by the National Science Centre project No. N N507 501339. The authors gratefully acknowledge Dr. Janusz
Sobczak and Dr. hab. Wojciech Lisowski from Institute of Physical
Chemistry of PAS for XPS surface analyses
X‐ray microtomography and phylogenomics provide insights into the morphology and evolution of an enigmatic mesozoic insect larva
Fossils sometimes show unusual morphological features absent in living organisms, making it difficult to reconstruct both their affinity and their function. We describe here a new lacewing larva, Ankyloleon caudatus gen. et sp.n. (Neuroptera) from the Cretaceous amber of Myanmar, characterized by an abdomen unique among insects, with ‘tail-like’ terminal segments bearing a ventral pair of vesicles. Phase-contrast X-ray microtomography reveals that these structures were dense and equipped with a median duct, suggesting that they were likely pygopods used for locomotion, holding the position through adhesive secretions. Our phylogenetic analyses, combining genomic and morphological data from both living and fossil lacewings, proved critical to placing Ankyloleon gen.n. on the lacewing tree of life as an early representative of the antlion clade, Myrmeleontiformia. These results corroborate the view that derived myrmeleontiform lacewings ‘experimented’ with unusual combinations of features and specializations during their evolutionary history, some of which are now lost
Sympathetic Background in Tolkien’s Prose
Considering Tolkien’s poetic sensitivity and love of nature, it is no wonder that his fiction abounds with natural images and landscape descriptions. More often than not, these references to the environment seem to be in harmony with the events or the structure of the story. In other words, Tolkien seems to resort to this old universal literary device usually referred to as “sympathetic background” whereby nature mirrors, mimics or reacts to the characters’ deeds, emotions or state of mind. As a contribution to previous and current studies on nature in Middle-earth, this paper examines Tolkien’s art in portraying nature — whether it be the immediate environment (geography, plants, animals …) , or the workings of the elements (the forces constituting the weather) — in an attempt to unveil a subtext under the prism of “sympathetic background”.
Passive phloem loading and long-distance transport in a synthetic tree-on-a-chip
Vascular plants rely on differences of osmotic pressure to export sugars from
regions of synthesis (mature leaves) to sugar sinks (roots, fruits). In this
process, known as M\"unch pressure flow, the loading of sugars from
photosynthetic cells to the export conduit (the phloem) is crucial, as it sets
the pressure head necessary to power long-distance transport. Whereas most
herbaceous plants use active mechanisms to increase phloem concentration above
that of the photosynthetic cells, in most tree species, for which transport
distances are largest, loading seems to occur via passive symplastic diffusion
from the mesophyll to the phloem. Here, we use a synthetic microfluidic model
of a passive loader to explore the nonlinear dynamics that arise during export
and determine the ability of passive loading to drive long-distance transport.
We first demonstrate that in our device, phloem concentration is set by the
balance between the resistances to diffusive loading from the source and
convective export through the phloem. Convection-limited export corresponds to
classical models of M\"unch transport, where phloem concentration is close to
that of the source; in contrast, diffusion-limited export leads to small phloem
concentrations and weak scaling of flow rates with the hydraulic resistance. We
then show that the effective regime of convection-limited export is predominant
in plants with large transport resistances and low xylem pressures. Moreover,
hydrostatic pressures developed in our synthetic passive loader can reach
botanically relevant values as high as 10 bars. We conclude that passive
loading is sufficient to drive long-distance transport in large plants, and
that trees are well suited to take full advantage of passive phloem loading
strategies
Dye molecules in electrolytes: new approach for suppression of dye-desorption in dye-sensitized solar cells
The widespread commercialization of dye-sensitized solar cells remains limited because of the poor long-term stability. We report on the influence of dye-molecules added in liquid electrolyte on long-term stability of dye-sensitized solar cells. Dye-desorption from the TiO2 surface during long-term cycling is one of the decisive factors that degrade photocurrent densities of devices which in turn determine the efficiencies of the devices. For the first time, desorption of dye from the TiO2 surface could be suppressed by controlling thermodynamic equilibrium; by addition of dye molecules in the electrolyte. The dye molecules in the electrolyte can suppress the driving forces for the adsorbed dye molecules to be desorbed from TiO2 nanoparticles. As a result, highly enhanced device stabilities were achieved due to the reduction of dye-desorption although there was a little decrease in the initial efficiencies.open4
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