3,000 research outputs found
Tracking Pacific bluefin tuna (Thunnus thynnus orientalis) in the northeastern Pacific with an automated algorithm that estimates latitude by matching sea-surface-temperature data from satellites with temperature data from tags on fish
Data recovered from 11 popup satellite archival tags and 3
surgically implanted archival tags were used to analyze the movement patterns of juvenile northern bluefin tuna (Thunnus thynnus orientalis) in the eastern Pacific. The light sensors on archival and pop-up satellite transmitting
archival tags (PSATs) provide data on the time of sunrise
and sunset, allowing the calculation of an approximate geographic position of the animal. Light-based estimates
of longitude are relatively robust but latitude estimates are prone to large degrees of error, particularly near the times of the equinoxes and when the tag is at low latitudes. Estimating latitude remains a problem for
researchers using light-based geolocation algorithms and it has been suggested that sea surface temperature data from satellites may be a useful tool for refining latitude estimates. Tag data from bluefin tuna were subjected to a newly developed algorithm, called “PSAT Tracker,” which automatically matches sea surface temperature data from the tags with sea surface temperatures recorded by satellites.
The results of this algorithm compared favorably to the estimates of latitude calculated with the lightbased
algorithms and allowed for estimation of fish positions during times of the year when the lightbased algorithms failed. Three near one-year tracks produced by PSAT tracker showed that the fish range from the California−Oregon border
to southern Baja California, Mexico, and that the majority of time is spent off the coast of central Baja Mexico. A seasonal movement pattern was evident; the fish spend winter and spring off central Baja California, and summer through fall is spent moving northward to Oregon and returning to Baja California
Reward-Predictive Clustering
Recent advances in reinforcement-learning research have demonstrated
impressive results in building algorithms that can out-perform humans in
complex tasks. Nevertheless, creating reinforcement-learning systems that can
build abstractions of their experience to accelerate learning in new contexts
still remains an active area of research. Previous work showed that
reward-predictive state abstractions fulfill this goal, but have only be
applied to tabular settings. Here, we provide a clustering algorithm that
enables the application of such state abstractions to deep learning settings,
providing compressed representations of an agent's inputs that preserve the
ability to predict sequences of reward. A convergence theorem and simulations
show that the resulting reward-predictive deep network maximally compresses the
agent's inputs, significantly speeding up learning in high dimensional visual
control tasks. Furthermore, we present different generalization experiments and
analyze under which conditions a pre-trained reward-predictive representation
network can be re-used without re-training to accelerate learning -- a form of
systematic out-of-distribution transfer
Hybrid Thermal Lance
The Hybrid Thermal Lance (HTL) is a device used to burn through landmines to destroy them safely. Designed for the team’s client, The HALO Trust, the HTL has proven to work well in destroying explosives, which has been demonstrated by field trials conducted in a number of countries including but not limited to Afghanistan and the Republic of Georgia. The HTL works by igniting acrylic burn tubes, which act as a fuel source and also focus the flame on a specific location on an explosive device. The system is controlled via a user-friendly, rugged control box that can run the HTL automatically and allow the device to burn for different lengths of time upon user command. The team was asked by HALO to make the HTL as user-friendly as possible. In order to do this, the team has been researching ways to make the ignition system as reliable as possible so the device works every time. The team plans to move forward in testing and refining the ignition system and the control circuit in order to give the client a trouble-free device. Future plans include designing a fixture that can be fitted over the end of the HTL burn tube which can focus the heat of the flame for a more concentrated burn.https://mosaic.messiah.edu/engr2020/1022/thumbnail.jp
Towards an embedding of Graph Transformation in Intuitionistic Linear Logic
Linear logics have been shown to be able to embed both rewriting-based
approaches and process calculi in a single, declarative framework. In this
paper we are exploring the embedding of double-pushout graph transformations
into quantified linear logic, leading to a Curry-Howard style isomorphism
between graphs and transformations on one hand, formulas and proof terms on the
other. With linear implication representing rules and reachability of graphs,
and the tensor modelling parallel composition of graphs and transformations, we
obtain a language able to encode graph transformation systems and their
computations as well as reason about their properties
The lower mass function of the young open cluster Blanco 1: from 30 Mjup to 3 Mo
We performed a deep wide field optical survey of the young (~100-150 Myr)
open cluster Blanco1 to study its low mass population well down into the brown
dwarf regime and estimate its mass function over the whole cluster mass
range.The survey covers 2.3 square degrees in the I and z-bands down to I ~ z ~
24 with the CFH12K camera. Considering two different cluster ages (100 and 150
Myr), we selected cluster member candidates on the basis of their location in
the (I,I-z) CMD relative to the isochrones, and estimated the contamination by
foreground late-type field dwarfs using statistical arguments, infrared
photometry and low-resolution optical spectroscopy. We find that our survey
should contain about 57% of the cluster members in the 0.03-0.6 Mo mass range,
including 30-40 brown dwarfs. The candidate's radial distribution presents
evidence that mass segregation has already occured in the cluster. We took it
into account to estimate the cluster mass function across the
stellar/substellar boundary. We find that, between 0.03Mo and 0.6Mo, the
cluster mass distribution does not depend much on its exact age, and is well
represented by a single power-law, with an index alpha=0.69 +/- 0.15. Over the
whole mass domain, from 0.03Mo to 3Mo, the mass function is better fitted by a
log-normal function with m0=0.36 +/- 0.07Mo and sigma=0.58 +/- 0.06. Comparison
between the Blanco1 mass function, other young open clusters' MF, and the
galactic disc MF suggests that the IMF, from the substellar domain to the
higher mass part, does not depend much on initial conditions. We discuss the
implications of this result on theories developed to date to explain the origin
of the mass distribution.Comment: 18 pages, 15 figures and 5 tables accepted in A&
Early assisted discharge with generic community nursing for chronic obstructive pulmonary disease exacerbations: Results of a randomised controlled tri
Objectives: To determine the effectiveness of early assisted discharge for chronic obstructive pulmonary disease (COPD) exacerbations, with home care provided by generic community nurses, compared with usual hospital care. Design: Prospective, randomised controlled and multicentre trial with 3-month follow-up. Setting: Five hospitals and three home care organisations in the Netherlands. Participants: Patients admitted to the hospital with an exacerbation of COPD. Patients with no or limited improvement of respiratory symptoms and patients with severe unstable comorbidities, social problems or those unable to visit the toilet independently were excluded. Intervention: Early discharge from hospital after 3 days inpatient treatment. Home visits by generic community nurses. Primary outcome measure was change in health status measured by the Clinical COPD Questionnaire (CCQ). Treatment failures, readmissions, mortality and change in generic health-related quality of life (HRQL) were secondary outcome measures. Results: 139 patients were randomised. No difference between groups was found in change in CCQ score at day 7 (difference in mean change 0.29 (95% CI -0.03 to 0.61)) or at 3 months (difference in mean change 0.04 (95% CI -0.40 to 0.49)). No difference was found in secondary outcomes. At day 7 there was a significant difference in change in generic HRQL, favouring usual hospital care. Conclusions: While patients' disease-specific health status after 7-day treatment tended to be somewhat better in the usual hospital care group, the difference was small and not clinically relevant or statistically significant. After 3 months, the difference had disappeared. A significant difference in generic HRQL at the end of the treatment had disappeared after 3 months and there was no difference in treatment failures, readmissions or mortality. Early assisted discharge with community nursing is feasible and an alternative to usual hospital care for selected patients with an acute COPD exacerbation
Natural Nuclear Reactor Oklo and Variation of Fundamental Constants Part 1: Computation of Neutronics of Fresh Core
Using modern methods of reactor physics we have performed full-scale
calculations of the natural reactor Oklo. For reliability we have used recent
version of two Monte Carlo codes: Russian code MCU REA and world wide known
code MCNP (USA). Both codes produce similar results. We have constructed a
computer model of the reactor Oklo zone RZ2 which takes into account all
details of design and composition. The calculations were performed for three
fresh cores with different uranium contents. Multiplication factors,
reactivities and neutron fluxes were calculated. We have estimated also the
temperature and void effects for the fresh core. As would be expected, we have
found for the fresh core a significant difference between reactor and Maxwell
spectra, which was used before for averaging cross sections in the Oklo
reactor. The averaged cross section of Sm-149 and its dependence on the shift
of resonance position (due to variation of fundamental constants) are
significantly different from previous results.
Contrary to results of some previous papers we find no evidence for the
change of the fine structure constant in the past and obtain new, most accurate
limits on its variation with time:
-4 10^{-17}year^{-1} < d alpha/dt/alpha < 3 10^{-17} year^{-1}
A further improvement in the accuracy of the limits can be achieved by taking
account of the core burnup. These calculations are in progress.Comment: 25 pages, 14 figures, 12 tables, minor corrections, typos correcte
Scn8a Antisense Oligonucleotide Is Protective in Mouse Models of SCN8A Encephalopathy and Dravet Syndrome
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154348/1/ana25676.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154348/2/ana25676_am.pd
Ab-initio structural, elastic, and vibrational properties of carbon nanotubes
A study based on ab initio calculations is presented on the estructural,
elastic, and vibrational properties of single-wall carbon nanotubes with
different radii and chiralities. We use SIESTA, an implementation of
pseudopotential-density-functional theory which allows calculations on systems
with a large number of atoms per cell. Different quantities like bond
distances, Young moduli, Poisson ratio and the frequencies of different phonon
branches are monitored versus tube radius. The validity of expectations based
on graphite is explored down to small radii, where some deviations appear
related to the curvature effects. For the phonon spectra, the results are
compared with the predictions of the simple zone-folding approximation. Except
for the known defficiencies of this approximation in the low-frequency
vibrational regions, it offers quite accurate results, even for relatively
small radii.Comment: 13 pages, 7 figures, submitted to Phys. Rev. B (11 Nov. 98
Food color is in the eye of the beholder: the role of human trichromatic vision in food evaluation
Non-human primates evaluate food quality based on brightness of red and green shades of color, with red signaling higher energy or greater protein content in fruits and leafs. Despite the strong association between food and other sensory modalities, humans, too, estimate critical food features, such as calorie content, from vision. Previous research primarily focused on the effects of color on taste/flavor identification and intensity judgments. However, whether evaluation of perceived calorie content and arousal in humans are biased by color has received comparatively less attention. In this study we showed that color content of food images predicts arousal and perceived calorie content reported when viewing food even when confounding variables were controlled for. Specifically, arousal positively co-varied with red-brightness, while green-brightness was negatively associated with arousal and perceived calorie content. This result holds for a large array of food comprising of natural food - where color likely predicts calorie content - and of transformed food where, instead, color is poorly diagnostic of energy content. Importantly, this pattern does not emerged with nonfood items. We conclude that in humans visual inspection of food is central to its evaluation and seems to partially engage the same basic system as non-human primates
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