213 research outputs found
Effective action of a five-dimensional domain wall
We calculate the four-dimensional low-energy effective action for the
perturbations of a two-scalar domain wall model in five dimensions. Comparison
of the effective action to the Nambu-Goto action reveals the presence of an
additional coupling between the light scalar field and the massless translation
mode (branon excitation), which can be written in terms of the curvature scalar
of the induced metric. We comment on the impact of this interaction to branon
physics.Comment: 24 page
On the thin-string limit of the 6d stringlike defect model
We show that in 6d models localizing gravity on stringlike defects and
satisfying the dominant energy condition, the metric exterior to the string
inevitably depends on the string's thickness. As a consequence, in the limit of
thin string either the gravity delocalizes, or the six-dimensional Planck scale
must be much larger that the four-dimensional one.Comment: 3 pages; v2: an alternative interpretation of our results, overlooked
in the first version, is adde
The fate of the zero mode of the five-dimensional kink in the presence of gravity
We investigate what becomes of the translational zero-mode of a
five-dimensional domain wall in the presence of gravity, studying the scalar
perturbations of a thick gravitating domain wall with AdS asymptotics and a
well-defined zero-gravity limit. Our analysis reveals the presence of a wide
resonance which can be seen as a remnant of the translational zero-mode present
in the domain wall in the absence of gravity and which ensures a continuous
change of the physical quantities (such as e.g. static potential between
sources) when the Planck mass is sent to infinity. Provided that the thickness
of the wall is much smaller than the AdS radius of the space-time, the
parameters of this resonance do not depend on details of the domain wall's
structure, but solely on the geometry of the space-time.Comment: 29 pages, 4 figures; v2: 2 machine-generated typos in the
introduction correcte
Quasilocalized gravity without asymptotic flatness
We present a toy model of a generic five-dimensional warped geometry in which
the 4D graviton is not fully localized on the brane. Studying the tensor sector
of metric perturbation around this background, we find that its contribution to
the effective gravitational potential is of 4D type (1/r) at the intermediate
scales and that at the large scales it becomes 1/r^{1+alpha}, 0<alpha=< 1 being
a function of the parameters of the model (alpha=1 corresponds to the
asymptotically flat geometry). Large-distance behavior of the potential is
therefore not necessarily five-dimensional. Our analysis applies also to the
case of quasilocalized massless particles other than graviton.Comment: 9 pages, 1 figure; to be published in Phys. Rev.
Label-free cell cycle analysis for high-throughput imaging flow cytometry
Imaging flow cytometry combines the high-throughput capabilities of conventional flow cytometry with single-cell imaging. Here we demonstrate label-free prediction of DNA content and quantification of the mitotic cell cycle phases by applying supervised machine learning to morphological features extracted from brightfield and the typically ignored darkfield images of cells from an imaging flow cytometer. This method facilitates non-destructive monitoring of cells avoiding potentially confounding effects of fluorescent stains while maximizing available fluorescence channels. The method is effective in cell cycle analysis for mammalian cells, both fixed and live, and accurately assesses the impact of a cell cycle mitotic phase blocking agent. As the same method is effective in predicting the DNA content of fission yeast, it is likely to have a broad application to other cell types
TOI-1199 b and TOI-1273 b: Two new transiting hot Saturns detected and characterized with SOPHIE and TESS
We report the characterization of two planet candidates detected by the
Transiting Exoplanet Survey Satellite (TESS), TOI-1199 b and TOI-1273 b, with
periods of 3.7 and 4.6 days, respectively. Follow-up observations for both
targets, which include several ground-based light curves, confirmed the transit
events. High-precision radial velocities from the SOPHIE spectrograph revealed
signals at the expected frequencies and phases of the transiting candidates and
allowed mass determinations with a precision of and for
TOI-1199 b and TOI-1273 b, respectively. The planetary and orbital parameters
were derived from a joint analysis of the radial velocities and photometric
data. We find that the planets have masses of
and and
radii of and
, respectively. The grazing transit of
TOI-1273 b translates to a larger uncertainty in its radius, and hence also in
its bulk density, compared to TOI-1199 b. The inferred bulk densities of
and
are among the lowest known for
exoplanets in this mass range, which, considering the brightness of the host
stars (), render them particularly amenable to
atmospheric characterization via the transit spectroscopy technique. The better
constraints on the parameters of TOI-1199 b provide a transmission spectroscopy
metric of , making it the better suited of the two planets for
atmospheric studies.Comment: Accepted for publication in A&A. 20 pages, 7 tables, and 15 figure
Plant trait and vegetation data along a 1314 m elevation gradient with fire history in Puna grasslands, Per\ufa
\ua9 2024. The Author(s). Alpine grassland vegetation supports globally important biodiversity and ecosystems that are increasingly threatened by climate warming and other environmental changes. Trait-based approaches can support understanding of vegetation responses to global change drivers and consequences for ecosystem functioning. In six sites along a 1314 m elevational gradient in Puna grasslands in the Peruvian Andes, we collected datasets on vascular plant composition, plant functional traits, biomass, ecosystem fluxes, and climate data over three years. The data were collected in the wet and dry season and from plots with different fire histories. We selected traits associated with plant resource use, growth, and life history strategies (leaf area, leaf dry/wet mass, leaf thickness, specific leaf area, leaf dry matter content, leaf C, N, P content, C and N isotopes). The trait dataset contains 3,665 plant records from 145 taxa, 54,036 trait measurements (increasing the trait data coverage of the regional flora by 420%) covering 14 traits and 121 plant taxa (ca. 40% of which have no previous publicly available trait data) across 33 families
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