The 2-Factor Polynomial Detects Even Perfect Matchings

In this paper, we prove that the 2-factor polynomial, an invariant of a planar trivalent graph with a perfect matching, counts the number of 2- factors that contain the the perfect matching as a subgraph. Consequently, we show that the polynomial detects even perfect matchings.Comment: 16 pages, 17 figure

Lifting Lagrangian immersions in CPn−1\mathbb{C} P^{n-1} to Lagrangian cones in Cn\mathbb{C}^n

In this paper we show how to lift Lagrangian immersions in $\mathbb{C} P^{n-1}$ to produce Lagrangian cones in $\mathbb{C} ^n$, and use this process to produce several families of examples of Lagrangian cones and special Lagrangian cones. Moreover we show how to produce Lagrangian cones, isotopic to the Harvey-Lawson and trivial cones, whose projections to $\mathbb{C} P^{n-1}$ are immersions with few transverse double points.Comment: 28 Pages, 7 figure

Sunlight to Convert Carbon Dioxide into Transportation Fuels

The proposed plant to convert sunlight and carbon dioxide to transportation fuels will utilize a Counter-Rotating Ring Receiver Reactor Recuperator (CR5) to convert carbon dioxide into carbon monoxide gas and oxygen gas. The CR5 is a solar chemical heat engine that provides an environment for the continuous reduction/oxidation of iron oxide, which allows for the reaction of carbon dioxide to carbon monoxide and oxygen. The plant will contain 150 CR5s each attached to its own parabolic mirror dish in order to collect sunlight. A carbon dioxide feed of approximately 25,070 kg/hr will be used to produce 9,520 kg/hr carbon monoxide. The devices will then feed a mixture of carbon dioxide and carbon monoxide gas to both a water gas shift reactor and a Fischer-Tropsch reactor. The Fischer- Tropsch reactor will use the carbon monoxide along with hydrogen gas produced from the water gas shift reactor to produce a range of hydrocarbon products following an Anderson- Schulz-Flory distribution centered around octane. The FT oil products (naphtha, gasoline, diesel, heavy ends) will be sold while the light-end products will be used to meet the utility requirements of the plant itself. The plant will be located in the western part of Texas in the Mojave Desert in order to take advantage of the high solar flux in this region. Due to the necessity of sunlight to provide energy for the CR5 reaction, the production of carbon monoxide will only take place during daylight hours and 2 hours worth of carbon monoxide production along with an excess of 10% of this amount will be stored in floating roof storage tanks. The storage of some extra carbon monoxide will keep the startup and shutdown production of petrol product constant as the sun rises and sets. The water gas shift reactions and Fischer- Tropsch reactors will operate for as long as carbon monoxide is available and will shut down once the carbon monoxide is depleted. Assuming a discount rate of 13%, the project yields a -$5.5 billion NPV over a 30 year time period. Based on this negative net present value, the plant proves to be economically unattractive. This result is primarily driven by high operating costs due to the high stress put on expensive catalysts that require frequent replacement as well as daily startup/shutdown costs. The largest negative economic factors in the plant projections are related to operating expenses. Specifically, the daily startup and shutdown costs associated with the CR5, WGS and FT reactors are significant. A related factor is the replacement cost of catalysts due to the high amounts of stress associated with daily shutdown, which requires 1 the catalysts to be replaced every 5 years. Storage tanks for continuous operation were considered, which would require 134 storage tanks total. This option is potentially more economically attractive; however, continuous operation was still discounted because the cost of maintenance, piping equipment costs, and other logistical challenges associated with housing the storage tanks. In addition, this option still produces a negative NPV after 30 years. Finally, the compressor operation requires significant electricity, factoring into the economic unattractiveness of the operation of this plant. These variables all lead to a negative net present value and negative cash on hand throughout thirty years of operation. Consequently, unless technological advancements can be made to change the fundamental operations of the sunlight to transportation fuel plant, the investment is not recommended

Thermoacclimatory variations in the activities of enzymes implicated in ion transport in the rainbow trout, salmo gairdneri

Two groups of rainbow trout were acclimated to 20 , 100 , and 18 o C. Plasma sodium, potassium, and chloride levels were determined for both. One group was employed in the estimation of branchial and renal (Na+-K+)-stimulated, (HC0 3-)-stimulated, and CMg++)-dependent ATPase activities, while the other was used in the measurement of carbonic anhydrase activity in the blood, gill and kidney. Assays were conducted using two incubation temperature schemes. One provided for incubation of all preparations at a common temperature of 2S oC, a value equivalent to the upper incipient lethal level for this species. In the other procedure the preparations were incubated at the appropriate acclimation temperature of the sampled fish. Trout were able to maintain plasma sodium and chloride levels essentially constant over the temperature range employed. The different incubation temperature protocols produced different levels of activity, and, in some cases, contrary trends with respect to acclimation temperature. This information was discussed in relation to previous work on gill and kidney. The standing-gradient flow hypothesis was discussed with reference to the structure of the chloride cell, known thermallyinduced changes in ion uptake, and the enzyme activities obtained in this study. Modifications of the model of gill lon uptake suggested by Maetz (1971) were proposed; high and low temperature models resulting. In short, ion transport at the gill at low temperatures appears to involve sodium and chloride 2 uptake by heteroionic exchange mechanisms working in association w.lth ca.rbonlc anhydrase. G.l ll ( Na + -K + ) -ATPase and erythrocyte carbonic anhydrase seem to provide the supplemental uptake required at higher temperatures. It appears that the kidney is prominent in ion transport at low temperatures while the gill is more important at high temperatures. 3 Linear regression analyses involving weight, plasma ion levels, and enzyme activities indicated several trends, the most significant being the interrelationship observed between plasma sodium and chloride. This, and other data obtained in the study was considered in light of the theory that a link exists between plasma sodium and chloride regulatory mechanisms

Assessing Medical Students\u27 Competence in Obtaining Informed Consent

BACKGROUND: Medical schools increasingly place emphasis on preparing students to perform routine, ethically important clinical activities with sensitivity and acumen. A method for evaluating students skills in obtaining informed consent that was created at our institution is described. METHODS: Formal assessment of medical students\u27 professional attitudes, values, and ethics skills occurs in the context of three required and developmentally attuned comprehensive examinations. A videotaped station tested senior medical students\u27 ability to obtain informed consent from a standardized patient who expresses concern about undergoing cardiac catheterization. Two checklists were completed by the patient. Videotapes were reviewed by a faculty member, and students\u27 reactions to the assessment experience were documented. RESULTS: Seventy-one senior students participated, and all performed well. Mean scores of 6.3 out of 7 (range 5 to 7, SD 5 0.5) on the informed consent checklist and 8.7 out of 9 (range 6 to 9, SD 5 0.5) on the communication skills checklist were obtained. Students endorsed the importance of the skills tested. CONCLUSIONS: This method of examining medical students\u27 abilities to obtain informed consent has several positive features and holds promise as an ethics competence assessment tool. Am J Surg. 1999;178:351—355. \xa9 1999 by Excerpta Medica, Inc.\u2

Evolution of Software-Only-Simulation at NASA IV and V

Software-Only-Simulations have been an emerging but quickly developing field of study throughout NASA. The NASA Independent Verification Validation (IVV) Independent Test Capability (ITC) team has been rapidly building a collection of simulators for a wide range of NASA missions. ITC specializes in full end-to-end simulations that enable developers, VV personnel, and operators to test-as-you-fly. In four years, the team has delivered a wide variety of spacecraft simulations that have ranged from low complexity science missions such as the Global Precipitation Management (GPM) satellite and the Deep Space Climate Observatory (DSCOVR), to the extremely complex missions such as the James Webb Space Telescope (JWST) and Space Launch System (SLS).This paper describes the evolution of ITCs technologies and processes that have been utilized to design, implement, and deploy end-to-end simulation environments for various NASA missions. A comparison of mission simulators are discussed with focus on technology and lessons learned in complexity, hardware modeling, and continuous integration. The paper also describes the methods for executing the missions unmodified flight software binaries (not cross-compiled) for verification and validation activities

Hypogravity reduces trunk admittance and lumbar muscle activation in response to external perturbations

Reduced paraspinal muscle size and flattening of spinal curvatures have been documented after spaceflight. Assessment of trunk adaptations to hypogravity can contribute to develop specific countermeasures. In this study, parabolic flights were used to investigate spinal curvature and muscle responses to hypogravity. Data from five trials at 0.25g, 0.50g and 0.75g were recorded from six participants, positioned in a kneeling-seated position. During the first two trials, participants maintained a normal, upright posture. In the last three trials, small-amplitude perturbations were delivered in the anterior direction at the T10 level. Spinal curvature was estimated using motion capture cameras. Trunk displacement and contact force between the actuator and participant were recorded. Muscle activity responses were collected using intramuscular electromyography (iEMG) of the deep and superficial lumbar multifidus, iliocostalis lumborum, longissimus thoracis, quadratus lumborum, transversus abdominis, obliquus internus and obliquus externus muscles. The root mean square iEMG and the average spinal angles were calculated. Trunk admittance and muscle responses to perturbations were calculated as closed-loop frequency response functions. Compared with 0.75g, 0.25g resulted in: lower activation of the longissimus thoracis (P=0.002); lower responses of the superficial multifidus at low frequencies (P=0.043); lower responses of the superficial multifidus (P=0.029) and iliocostalis lumborum (P=0.043); lower trunk admittance (P=0.037) at intermediate frequencies; and stronger responses of the transversus abdominis at higher frequencies (p=0.032). These findings indicate that exposure to hypogravity reduces trunk admittance, partially compensated by weaker stabilizing contributions of the paraspinal muscles and coinciding with an apparent increase of the deep abdominal muscle activity