155 research outputs found
Plasticity of Foot Muscle and Cardiac Thermal Limits in the Limpet \u3cem\u3eLottia limatula\u3c/em\u3e from Locations with Differing Temperatures
Species distributions are shifting in response to increased habitat temperatures as a result of ongoing climate change. Understanding variation in physiological plasticity among species and populations is important for predicting these distribution shifts. Interspecific variation in intertidal ectotherms’ short-term thermal plasticity has been well established. However, intraspecific variation among populations from differing thermal habitats remains a question pertinent to understanding the effects of climate change on species’ ranges. In this study, we explored upper thermal tolerance limits and plasticity of those limits using a foot muscle metric and 2 cardiac metrics (Arrhenius breakpoint temperature, ABT, and flatline temperature, FLT) in adult file limpets Lottia limatula. Limpets were collected from thermally different coastal and inland-estuarine habitats and held for 2 wk at 13, 17 or 21°C prior to thermal performance assays. Compared to limpets from the warm estuary site, limpets from the cold outer coast site had similar foot muscle critical thermal maxima (CTmax; 35.2 vs. 35.6°C) but lower cardiac thermal tolerances (ABT: 30.5 vs. 35.1°C). Limpets from the cold coast site had higher acclimation responses in foot muscle CTmax (0.22°C per 1°C rise in acclimation) than those of the warm estuary site (0.07°C per 1°C rise in acclimation), but lower acclimation responses in cardiac thermal tolerance (ABT: -0.85°C per 1°C rise in acclimation) than those of the estuary site (ABT: 0.10°C per 1°C rise in acclimation). Since outer coast populations had lower cardiac plasticity and higher mortalities in the warm acclimation, we predict L. limatula from colder habitats will be more susceptible to rising temperatures. Our findings illustrate the importance of population-specific variation in short-term thermal plasticity when considering the effects of climate change on ectotherms
Blood-coated sensor for high-throughput ptychographic cytometry on a Blu-ray disc
Blu-ray drive is an engineering masterpiece that integrates disc rotation,
pickup head translation, and three lasers in a compact and portable format.
Here we integrate a blood-coated image sensor with a modified Blu-ray drive for
high-throughput cytometric analysis of various bio-specimens. In this device,
samples are mounted on the rotating Blu-ray disc and illuminated by the
built-in lasers from the pickup head. The resulting coherent diffraction
patterns are then recorded by the blood-coated image sensor. The rich spatial
features of the blood-cell monolayer help down-modulate the object information
for sensor detection, thus forming a high-resolution computational bio-lens
with a theoretically unlimited field of view. With the acquired data, we
develop a lensless coherent diffraction imaging modality termed rotational
ptychography for image reconstruction. We show that our device can resolve the
435 nm linewidth on the resolution target and has a field of view only limited
by the size of the Blu-ray disc. To demonstrate its applications, we perform
high-throughput urinalysis by locating disease-related calcium oxalate crystals
over the entire microscope slide. We also quantify different types of cells on
a blood smear with an acquisition speed of ~10,000 cells per second. For in
vitro experiment, we monitor live bacterial cultures over the entire Petri dish
with single-cell resolution. Using biological cells as a computational lens
could enable new intriguing imaging devices for point-of-care diagnostics.
Modifying a Blu-ray drive with the blood-coated sensor further allows the
spread of high-throughput optical microscopy from well-equipped laboratories to
citizen scientists worldwide
A Farm-to-Fork Quantitative Microbial Exposure Assessment of β-Lactam-Resistant \u3ci\u3eEscherichia coli\u3c/i\u3e among U.S. Beef Consumers
Integrated quantitative descriptions of the transmission of β-lactam-resistant Escherichia coli (BR-EC) from commercial beef products to consumers are not available. Here, a quantitative microbial exposure assessment model was established to simulate the fate of BR-EC in a farm-to-fork continuum and provide an estimate of BR-EC exposure among beef consumers in the U.S. The model compared the per-serving exposures from the consumption of intact beef cuts, non-intact beef cuts, and ground beef. Additionally, scenario analysis was performed to evaluate the relative contribution of antibiotic use during beef cattle production to the level of human exposure to BR-EC. The model predicted mean numbers of BR-EC of 1.7 x 10-4, 8.7 x 10-4, and 6.9 x 10-1 CFU/serving for intact beef cuts, non-intact beef cuts, and ground beef, respectively, at the time of consumption. Sensitivity analyses using the baseline model suggested that factors related to sectors along the supply chain, i.e., feedlots, processing plants, retailers, and consumers, were all important for controlling human exposure to BR-EC. Interventions at the processing and post-processing stages are expected to be most effective. Simulation results showed that a decrease in antibiotic use among beef cattle might be associated with a reduction in exposure to BR-EC from beef consumption. However, the absolute reduction was moderate, indicating that the effectiveness of restricting antibiotic use as a standalone strategy for mitigating human exposure to BR-EC through beef consumption is still uncertain. Good cooking and hygiene practices at home and advanced safety management practices in the beef processing and post-processing continuum are more powerful approaches for reducing human exposure to antibiotic-resistant bacteria in beef products
Nerfstudio: A Modular Framework for Neural Radiance Field Development
Neural Radiance Fields (NeRF) are a rapidly growing area of research with
wide-ranging applications in computer vision, graphics, robotics, and more. In
order to streamline the development and deployment of NeRF research, we propose
a modular PyTorch framework, Nerfstudio. Our framework includes plug-and-play
components for implementing NeRF-based methods, which make it easy for
researchers and practitioners to incorporate NeRF into their projects.
Additionally, the modular design enables support for extensive real-time
visualization tools, streamlined pipelines for importing captured in-the-wild
data, and tools for exporting to video, point cloud and mesh representations.
The modularity of Nerfstudio enables the development of Nerfacto, our method
that combines components from recent papers to achieve a balance between speed
and quality, while also remaining flexible to future modifications. To promote
community-driven development, all associated code and data are made publicly
available with open-source licensing at https://nerf.studio.Comment: Project page at https://nerf.studi
Chandra ACIS Survey of M33 (ChASeM33): The enigmatic X-ray emission from IC131
We present the first X-ray analysis of the diffuse hot ionized gas and the
point sources in IC131, after NGC604 the second most X-ray luminous giant HII
region in M33. The X-ray emission is detected only in the south eastern part of
IC131 (named IC131-se) and is limited to an elliptical region of ~200pc in
extent. This region appears to be confined towards the west by a hemispherical
shell of warm ionized gas and only fills about half that volume. Although the
corresponding X-ray spectrum has 1215 counts, it cannot conclusively be told
whether the extended X-ray emission is thermal, non-thermal, or a combination
of both. A thermal plasma model of kT_e=4.3keV or a single power law of
Gamma=2.1 fit the spectrum equally well. If the spectrum is purely thermal
(non-thermal), the total unabsorbed X-ray luminosity in the 0.35-8keV energy
band amounts to L_X = 6.8(8.7)x10^35erg/s. Among other known HII regions
IC131-se seems to be extreme regarding the combination of its large extent of
the X-ray plasma, the lack of massive O stars, its unusually high electron
temperature (if thermal), and the large fraction of L_X emitted above 2keV
(~40-53%). A thermal plasma of ~4keV poses serious challenges to theoretical
models, as it is not clear how high electron temperatures can be produced in
HII regions in view of mass-proportional and collisionless heating. If the gas
is non-thermal or has non-thermal contributions, synchrotron emission would
clearly dominate over inverse Compton emission. It is not clear if the same
mechanisms which create non-thermal X-rays or accelerate CRs in SNRs can be
applied to much larger scales of 200pc. In both cases the existing theoretical
models for giant HII regions and superbubbles do not explain the hardness and
extent of the X-ray emission in IC131-se.Comment: 28 pages, 7 figures and 2 tables. Accepted for publication in ApJ.
For a high resolution version of the paper see
http://hea-www.harvard.edu/vlp_m33_public/publications.htm
Biosensing for the Environment and Defence: Aqueous Uranyl Detection Using Bacterial Surface Layer Proteins
The fabrication of novel uranyl (UO22+) binding protein based sensors is reported. The new biosensor responds to picomolar levels of aqueous uranyl ions within minutes using Lysinibacillus sphaericus JG-A12 S-layer protein tethered to gold electrodes. In comparison to traditional self assembled monolayer based biosensors the porous bioconjugated layer gave greater stability, longer electrode life span and a denser protein layer. Biosensors responded specifically to UO22+ ions and showed minor interference from Ni2+, Cs+, Cd2+ and Co2+. Chemical modification of JG-A12 protein phosphate and carboxyl groups prevented UO22+ binding, showing that both moieties are involved in the recognition to UO22+
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