2,486 research outputs found
Re-examination of the Effects of Food Abundance on Jaw Plasticity in Purple Sea Urchins
Morphological plasticity is a critical mechanism that animals use to cope with variations in resource availability. During periods of food scarcity, sea urchins demonstrate an increase in jaw length relative to test diameter. This trait is thought to be reversible and adaptive by yielding an increase in feeding efficiency. We directly test the hypotheses that (1) there are reversible shifts in jaw length to test diameter ratios with food abundance in individual urchins, and (2) these shifts alter feeding efficiency. Purple sea urchins, Strongylocentrotus purpuratus, were collected and placed in either high or low food treatments for 3 months, after which treatments were switched for two additional months between February and September, 2015 in La Jolla, CA (32.8674°N, 117.2530°W). Measurements of jaw length to test diameter ratios were significantly higher in low compared to high food urchins, but this was due to test growth in the high food treatments. Ratios of low food urchins did not change following a switch to high food conditions, indicating that this trait is not reversible within the time frame of this study. Relatively longer jaws were also not correlated with increased feeding efficiency. We argue that jaw length plasticity is not adaptive and is simply a consequence of exposure to high food availability, as both jaw and test growth halt when food is scarce
The Stress Distribution on the Zygapophyseal Joint of Lumbar Vertebra by ANSYS Program
Zygapophyseal joints (or facet joints), are a plane synovial joint which located between the articular facet processes of the vertebral arch which is freely guided movable joints. Ten dried vertebrae were used for the lumbar region and taking (L4) as a sample to reveal stress pathways across the joints by using ANSYS program under different loading conditions which used Finite Elements Analysis model. Results obtained from the ANSYS program are important in understanding the boundary conditions for load analysis and the points of stress concentration which explained from the anatomical point of view and linked to muscle and ligament attachments. This model used as a computational tool to joint biomechanics and to prosthetic implant analysis
Evaluation of a method for fusing LIDAR data and multispectral images for building detection
In this paper, we describe the evaluation of a method for building detection by the Dempster-Shafer fusion of LIDAR data and multispectral images. For that purpose, ground truth was digitised for two test sites with quite different characteristics. Using these data sets, the heuristic model for the probability mass assignments of the method is validated, and rules for the tuning of the parameters of this model are discussed. Further we evaluate the contributions of the individual cues used in the classification process to the quality of the classification results. Our results show the degree to which the overall correctness of the results can be improved by fusing LIDAR data with multispectral images
Oil recovery through deemulsification research : separation of water from emulsified oil
In an effort to improve the environment, there is a need to recover and reuse the oil and water components of lubricating emulsions used in copper drawing and rolling processes. The Freeport-McMoRan Copper and Gold Inc. copper rod mill located in El Paso, TX was chosen as the site location for this project. It is one of the largest rolling and drawing operation facilities in the world, and it meets the established criteria set by Project ORDER. A large facility generates an average of 8,400 gallons of spent lubricant per day. The WERC emulsion sample contains 98 v% water and 2 v% lubricating oil and contains metal debris that would negatively impact water quality if it were discharged into surface waters. Oil and water are valuable resources and their maximum recoveries are desired. Project ORDER successfully recovers more than 90 v% of the water and essentially all of the oil. The recovered water could be recycled for fresh lubricant production within the facility, eliminating almost all water discharge and reducing water intake. The recovered oil will be sent to oil recyclers, lowering discharge expenses. Project ORDER has carefully evaluated several water recovery, oil recovery, and metal recovery technologies to design the commercial process. The first processing step of Project ORDER is an ultrafiltration (UF) membrane that recovers 90 v% of the water in the spent emulsion sample. As water permeates the membrane, the concentration of oil in the emulsion increases from about 2 v% to 30 v%. The second processing step removes essentially all of the water from the UF concentrate using an evaporator, which operates by passing low pressure steam through a jacketed, agitated vessel. The third processing step removes metal debris from the oil using a depth filter. The fourth processing step utilizes a reverse osmosis (RO) membrane to purify the UF permeate water for recycle. The fifth processing step reduces the amount of waste from the RO reject using an evaporator, which also operates by passing low pressure steam through a jacketed, agitated vessel. The evaporator removes essentially all of the water in the RO reject and the remaining waste is sent for disposal. The evaporated water from both evaporation units is condensed and combined with the RO permeate to be recycled. Based on a spent emulsion production rate of 8,400 gal/day, it costs 899,000, the yearly operating cost is 413,000 with a 24% discounted rate of return. After the initial investment is recovered, Project ORDER results in a net savings of $265,000 per year. This project is a promising process to achieve all the goals of Task 5. It produces oil with less than 3% water content, produces maximum water yield, minimizes waste solution, avoids the use of harmful materials and is cost and energy efficient. The health and safety of all individuals involved and the environmental impact of Project ORDER is of utmost importance throughout the construction and life of the project. The facility will ensure that all processes will comply with regulations outlined by the Environmental Protection Agency (EPA), Occupational Safety and Health Administration (OSHA), the Resource Conservation and Recovery Act (RCRA), and Texas State and El Paso County regulations. All operations and company procedures will comply with The Emergency Planning and Community Right-to-Know Act of 1986. The following report provides a detailed proposal for an oil and water recovery system, including experimental research results, process optimization, full-scale design, economic analysis, and environmental, health and safety considerations
A Detect and Avoid System in the Context of Multiple-Unmanned Aircraft Systems Operations
NASA's Unmanned Aircraft Systems Integration into the National Airspace System (UAS in the NAS) project examines the technical barriers associated with the operation of UAS in civil airspace. For UAS, the removal of the pilot from onboard the aircraft has eliminated the ability of the ground-based pilot in command (PIC) to use out-the-window visual information to make judgements about a potential threat of a loss of well clear with another aircraft. NASA's Phase 1 research supported the development of a Detect and Avoid (DAA) system that supports the ground-based pilot's ability to detect potential traffic conflicts and determine a resolution maneuver, but existing display/alerting requirements did not account for multiple UAS control (1:N). Demands for increased scalability of UAS in the NAS operations are expected to create a need for simultaneous control of UAs, and thus, a new DAA HMI design will likely be necessary. Previous research, however, has found performance degradations as the number of vehicles under operator control has increased. The purpose of the current human-in-the-loop (HITL) simulation was to examine the viability of 1:N operations with the Phase 1 DAA alerting and guidance. Sixteen UAS pilots flew three scenarios with varying number of UAs under their control (1:1, 1:3, 1:5). In addition to their supervisory and sensor mission responsibilities, pilots were to utilize the DAA system to remain DAA well clear (DWC) during scripted conflicts of mixed severity. Measured response times, separation performance, mission task data, and subjective feedback were collected to assess how the multi-UAS control configuration impacted pilots' ability to maintain DAA well clear and perform the mission tasks. Overall, the DAA system proved surprisingly adaptive to multi-UAS control for preventing losses of DAA well clear (LoDWC). The findings suggest that, while multi-UAS operators are able to maintain safe separation (DWC) from other traffic, their ability to efficiently perform missions drastically decreases with their number of controlled vehicles. Pilot feedback indicated that, for this context, the use of automation support tools for completing and managing mission tasks would be appropriate and desired, especially for ensuring efficient use of assets. Finally, human-machine interface (HMI) design considerations for multi-UAS operations are discussed
Optical Breath Gas Sensor for Extravehicular Activity Application
The function of the infrared gas transducer used during extravehicular activity in the current space suit is to measure and report the concentration of carbon dioxide (CO2) in the ventilation loop. The next generation portable life support system (PLSS) requires next generation CO2 sensing technology with performance beyond that presently in use on the Space Shuttle/International Space Station extravehicular mobility unit (EMU). Accommodation within space suits demands that optical sensors meet stringent size, weight, and power requirements. A laser diode spectrometer based on wavelength modulation spectroscopy is being developed for this purpose by Vista Photonics, Inc. Two prototype devices were delivered to NASA Johnson Space Center (JSC) in September 2011. The sensors incorporate a laser diode-based CO2 channel that also includes an incidental water vapor (humidity) measurement and a separate oxygen channel using a vertical cavity surface emitting laser. Both prototypes are controlled digitally with a field-programmable gate array/microcontroller architecture. The present development extends and upgrades the earlier hardware to the Advanced PLSS 2.0 test article being constructed and tested at JSC. Various improvements to the electronics and gas sampling are being advanced by this project. The combination of low power electronics with the performance of a long wavelength laser spectrometer enables multi-gas sensors with significantly increased performance over that presently offered in the EMU
Increased circulating ANG II and TNF-α represents important risk factors in obese Saudi adults with hypertension irrespective of diabetic status and BMI
Central adiposity is a significant determinant of obesity-related hypertension risk, which may arise due to the pathogenic inflammatory nature of the abdominal fat depot. However, the influence of pro-inflammatory adipokines on blood pressure in the obese hypertensive phenotype has not been well established in Saudi subjects. As such, our study investigated whether inflammatory factors may represent useful biomarkers to delineate hypertension risk in a Saudi cohort with and without hypertension and/or diabetes mellitus type 2 (DMT2). Subjects were subdivided into four groups: healthy lean controls (age: 47.9±5.1 yr; BMI: 22.9±2.1 Kg/m2), non-hypertensive obese (age: 46.1±5.0 yr; BMI: 33.7±4.2 Kg/m2), hypertensive obese (age: 48.6±6.1 yr; BMI: 36.5±7.7 Kg/m2) and hypertensive obese with DMT2 (age: 50.8±6.0 yr; BMI: 35.3±6.7 Kg/m2). Anthropometric data were collected from all subjects and fasting blood samples were utilized for biochemical analysis. Serum angiotensin II (ANG II) levels were elevated in hypertensive obese (p<0.05) and hypertensive obese with DMT2 (p<0.001) compared with normotensive controls. Systolic blood pressure was positively associated with BMI (p<0.001), glucose (p<0.001), insulin (p<0.05), HOMA-IR (p<0.001), leptin (p<0.01), TNF-α (p<0.001) and ANG II (p<0.05). Associations between ANG II and TNF-α with systolic blood pressure remained significant after controlling for BMI. Additionally CRP (p<0.05), leptin (p<0.001) and leptin/adiponectin ratio (p<0.001) were also significantly associated with the hypertension phenotype. In conclusion our data suggests that circulating pro-inflammatory adipokines, particularly ANG II and, TNF-α, represent important factors associated with a hypertension phenotype and may directly contribute to predicting and exacerbating hypertension risk
SURVEY OF THE DEPENDENCE ON TEMPERATURE OF THE COERCIVITY OF GARNET-FILMS
The temperature dependence of the domain-wall coercive field of epitaxial magnetic garnets films
has been investigated in the entire temperature range of the ferrimagnetic phase, and has been found
to be described by a set of parametric exponents. In subsequent temperature regions different slopes
were observed, with breaking points whose position was found to be sample dependent. A survey
ba.ed on literature Data as well as on a large number of our own samples shows the general
existence of this piecewise exponential dependence and the presence of the breaking points. This
type of domain-wall coercive field temperature dependence was found in all samples in the large
family of the epitaxial garnets (about 30 specimens of more than ten chemical compositionsj and
also in another strongly anisotropic material (TbFeCo)
Comparing community structure identification
We compare recent approaches to community structure identification in terms
of sensitivity and computational cost. The recently proposed modularity measure
is revisited and the performance of the methods as applied to ad hoc networks
with known community structure, is compared. We find that the most accurate
methods tend to be more computationally expensive, and that both aspects need
to be considered when choosing a method for practical purposes. The work is
intended as an introduction as well as a proposal for a standard benchmark test
of community detection methods.Comment: 10 pages, 3 figures, 1 table. v2: condensed, updated version as
appears in JSTA
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