115 research outputs found
BIOSORPTION OF COPPER (II) BY BROWN SEAWEED SARGASSUM ILICIFOLIUM (TURNER) C. AGARDH
The biosorption of copper (II) on Sargassum ilicifolium biomass was investigated. Batch biosorption experiments were conducted to determine the biosorption properties of the biomass and it was observed that the maximum capacity of copper uptake was around 47% at pH 4.5 during one hour with 1000 mg/L of initial concentration and 100mg algal material. Increased biomass 500 mg accelerated the rate of removal of metal to more than 90% at the similar pH value. Fourier transform infrared spectroscopy analysis of algal biomass revealed the presence of amino, carboxyl, hydroxyl and carbonyl group, which are responsible for biosorption of metal ions. SEM analysis revealed cross linkage between the copper ions and the organic functional groups of the biomass
A super-Earth-sized planet orbiting in or near the habitable zone around Sun-like star
We present the discovery of a super-earth-sized planet in or near the
habitable zone of a sun-like star. The host is Kepler-69, a 13.7 mag G4V-type
star. We detect two periodic sets of transit signals in the three-year flux
time series of Kepler-69, obtained with the Kepler spacecraft. Using the very
high precision Kepler photometry, and follow-up observations, our confidence
that these signals represent planetary transits is >99.1%. The inner planet,
Kepler-69b, has a radius of 2.24+/-0.4 Rearth and orbits the host star every
13.7 days. The outer planet, Kepler-69c, is a super-Earth-size object with a
radius of 1.7+/-0.3 Rearth and an orbital period of 242.5 days. Assuming an
Earth-like Bond albedo, Kepler-69c has an equilibrium temperature of 299 +/- 19
K, which places the planet close to the habitable zone around the host star.
This is the smallest planet found by Kepler to be orbiting in or near habitable
zone of a Sun-like star and represents an important step on the path to finding
the first true Earth analog.Comment: Accepted for publication in the Astrophysical Journa
Detection of Potential Transit Signals in Sixteen Quarters of Kepler Mission Data
We present the results of a search for potential transit signals in four
years of photometry data acquired by the Kepler Mission. The targets of the
search include 111,800 stars which were observed for the entire interval and
85,522 stars which were observed for a subset of the interval. We found that
9,743 targets contained at least one signal consistent with the signature of a
transiting or eclipsing object, where the criteria for detection are
periodicity of the detected transits, adequate signal-to-noise ratio, and
acceptance by a number of tests which reject false positive detections. When
targets that had produced a signal were searched repeatedly, an additional
6,542 signals were detected on 3,223 target stars, for a total of 16,285
potential detections. Comparison of the set of detected signals with a set of
known and vetted transit events in the Kepler field of view shows that the
recovery rate for these signals is 96.9%. The ensemble properties of the
detected signals are reviewed.Comment: Accepted by ApJ Supplemen
Planetary Candidates Observed by Kepler V: Planet Sample from Q1-Q12 (36 Months)
The Kepler mission discovered 2842 exoplanet candidates with 2 years of data.
We provide updates to the Kepler planet candidate sample based upon 3 years
(Q1-Q12) of data. Through a series of tests to exclude false-positives,
primarily caused by eclipsing binary stars and instrumental systematics, 855
additional planetary candidates have been discovered, bringing the total number
known to 3697. We provide revised transit parameters and accompanying posterior
distributions based on a Markov Chain Monte Carlo algorithm for the cumulative
catalogue of Kepler Objects of Interest. There are now 130 candidates in the
cumulative catalogue that receive less than twice the flux the Earth receives
and more than 1100 have a radius less than 1.5 Rearth. There are now a dozen
candidates meeting both criteria, roughly doubling the number of candidate
Earth analogs. A majority of planetary candidates have a high probability of
being bonafide planets, however, there are populations of likely
false-positives. We discuss and suggest additional cuts that can be easily
applied to the catalogue to produce a set of planetary candidates with good
fidelity. The full catalogue is publicly available at the NASA Exoplanet
Archive.Comment: Accepted for publication, ApJ
Planetary Candidates Observed by Kepler. VII. The First Fully Uniform Catalog Based on The Entire 48 Month Dataset (Q1-Q17 DR24)
We present the seventh Kepler planet candidate catalog, which is the first to
be based on the entire, uniformly processed, 48 month Kepler dataset. This is
the first fully automated catalog, employing robotic vetting procedures to
uniformly evaluate every periodic signal detected by the Q1-Q17 Data Release 24
(DR24) Kepler pipeline. While we prioritize uniform vetting over the absolute
correctness of individual objects, we find that our robotic vetting is overall
comparable to, and in most cases is superior to, the human vetting procedures
employed by past catalogs. This catalog is the first to utilize artificial
transit injection to evaluate the performance of our vetting procedures and
quantify potential biases, which are essential for accurate computation of
planetary occurrence rates. With respect to the cumulative Kepler Object of
Interest (KOI) catalog, we designate 1,478 new KOIs, of which 402 are
dispositioned as planet candidates (PCs). Also, 237 KOIs dispositioned as false
positives (FPs) in previous Kepler catalogs have their disposition changed to
PC and 118 PCs have their disposition changed to FP. This brings the total
number of known KOIs to 8,826 and PCs to 4,696. We compare the Q1-Q17 DR24 KOI
catalog to previous KOI catalogs, as well as ancillary Kepler catalogs, finding
good agreement between them. We highlight new PCs that are both potentially
rocky and potentially in the habitable zone of their host stars, many of which
orbit solar-type stars. This work represents significant progress in accurately
determining the fraction of Earth-size planets in the habitable zone of
Sun-like stars. The full catalog is publicly available at the NASA Exoplanet
Archive.Comment: Accepted to the Astrophysical Journal Supplement Series. 30 pages, 9
figures, 7 tables. We make the DR24 robovetter decision code publicly
available at http://github.com/JeffLCoughlin/robovetter, with input and
output examples provided using the same data as contained in the full paper's
table
Planetary Candidates Observed by Kepler VI: Planet Sample from Q1-Q16 (47 Months)
\We present the sixth catalog of Kepler candidate planets based on nearly 4
years of high precision photometry. This catalog builds on the legacy of
previous catalogs released by the Kepler project and includes 1493 new Kepler
Objects of Interest (KOIs) of which 554 are planet candidates, and 131 of these
candidates have best fit radii <1.5 R_earth. This brings the total number of
KOIs and planet candidates to 7305 and 4173 respectively. We suspect that many
of these new candidates at the low signal-to-noise limit may be false alarms
created by instrumental noise, and discuss our efforts to identify such
objects. We re-evaluate all previously published KOIs with orbital periods of
>50 days to provide a consistently vetted sample that can be used to improve
planet occurrence rate calculations. We discuss the performance of our planet
detection algorithms, and the consistency of our vetting products. The full
catalog is publicly available at the NASA Exoplanet Archive.Comment: 18 pages, to be published in the Astrophysical Journal Supplement
Serie
Fourier-Feature MLP Toolkit for GPU-Accelerated Cardiac-MRI 4DCMR Strain Analysis
This paper explores the embedding of a Fourier-Feature—enhanced multiplayer perceptron(MLP-FEE) at the heart of a newly refactored python workflow for four-dimensional cardiac-MRI strain quantification demonstrating how a single, compact network can outperform traditional convolution and spline-based methods. The original code, capable of orientation normalization, displacement tracking, and finite-difference strain computation, has been translated and consolidated into pytorch. By injecting sinusoidal positional encodings at the network’s input layer supplied a rich set of high-frequency basis functions hence enabling multilayer MLP to resolve gradients that cubic splines and conventional CNNs typically blur or struggle with. Profiling on an Apple-silicon GPU shows interactive inference without hand-tuned CUDA alongside a network has a higher precision while trimming code complexity by roughly 50%. Qualitative comparison with finite-element ground truths confirms preservation of peak systolic strain and segment-wise GLS trends. Meanwhile, the transpilation preserves domain-specific algorithms while exposing them to modern deep-learning tooling along with swappable optimisers and augmentation strategies. By showcasing the power of Fourier features inside a lightweight MLP, this work illustrates a path for researchers to migrate legacy workflows into a GPU-accelerated, open-source ecosystem to unlock higher-resolution insights across a variety of Biomedical Engineering datasets
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