1,794 research outputs found
Adaptation of time line analysis program to single pilot instrument flight research
A data base was developed for SPIFR operation and the program was run. The outputs indicated that further work was necessary on the workload models. In particular, the workload model for the cognitive channel should be modified as the output workload appears to be too small. Included in the needed refinements are models to show the workload when in turbulence, when overshooting a radial or glideslope, and when copying air traffic control clearances
Individual recognition between mother and infant bats (Myotis)
The recognition process and the basis for that recognition, in brown bats, between mother and infant are analyzed. Two parameters, ultrasonic communication and olfactory stimuli, are investigated. The test animals were not allowed any visual contact. It was concluded that individual recognition between mother and infant occurred. However, it could not be determined if the recognition was based on ultrasonic signals or olfactory stimuli
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PHYSIOLOGY OF A BASAL VERTEBRATE, THE SEA LAMPREY (PETROMYZON MARINUS): OSMOREGULATION AND CORTICOSTEROID ACTION
Lamprey represent the most basal living example of a vertebrate animal which regulates its internal fluid and ion homeostasis. This phylogenetic position among vertebrates makes lamprey an important model organism for understanding the basal state, and thus the evolution, of physiological systems such as the mechanisms of osmo- and ionoregulation and the endocrine factors controlling them. Sea lamprey (Petromyzon marinus) are an anadromous fish, migrating from freshwater (FW) to seawater (SW) as juveniles, then returning back upstream as mature adults to spawn. Surviving this transition from a solute-poor FW environment to a solute-concentrated SW environment requires many changes to osmo- and ionoregulatory mechanisms, which are driven, in part, by signaling from corticosteroid hormones. Much of this dissertation examines the molecular mechanisms for osmo- and ionoregulation in the lamprey gill and intestine and how corticosteroids control osmoregulatory processes in these tissues. Additionally, effect of temperature on osmoregulation, and the corticosteroid response to handling and thermal stressors are also examined. I report the results of experiments that were designed to identify molecular and organismal processes driving physiological acclimation to FW or SW residence. Special attention was given to understanding the endogenous nature of sea lamprey physiology, particularly regarding the development of the ability to survive and osmoregulate in SW that occurs during the larvae-to-juvenile metamorphosis. In Chapter 1, I offer an introduction to basic sea lamprey biology and physiology, including background on osmoregulation and corticosteroid action in fishes. In Chapter 2, I functionally characterize a critical ion transporter in the gills of SW-acclimated fishes responsible for Cl- secretion, the Na+/K+/2Cl- cotransporter (NKCC1). I demonstrate that (i) a membrane-bound NKCC1 is upregulated in the gills of sea lamprey during metamorphosis in preparation for SW migration; (ii) the timing of gill NKCC1 upregulation corresponds to the upregulation of another critical ion transporter and biomarker of ionoregulatory activity in fish gills, Na+/K+-ATPase (NKA), as well as the acquisition of SW tolerance; and (iii) pharmacological inhibition of NKCC1 markedly decreases SW tolerance in juvenile sea lamprey. In Chapter 3, I describe branchiometric changes that occur during the sea lamprey metamorphosis and SW acclimation, such as an increase in the branchiosomatic index (percentage of total body weight contributed by the gills) and a redistribution of the gill pouch-specific contribution to total gill NKA activity. In Chapters 4 and 5, I characterize 11-deoxycortisol as the endogenous corticosteroid hormone that controls osmo- and ionoregulation in the gills and intestine of sea lamprey. I show that (i) 11-deoxycortisol and its corticosteroid receptor (CR) are upregulated during metamorphosis and after exposure to SW; (ii) that the CR present in the gill and intestine are highly specific to binding by 11-deoxycortisol; and (iii) only 11-deoxycortisol (and not deoxycorticosterone, the other endogenous corticosteroid in lamprey blood) can upregulate osmo- and ionoregulatory mechanisms and SW tolerance in metamorphosing sea lamprey. In Chapter 6, I describe the glucose stimulating action of 11-deoxycortisol. I demonstrate that (i) lamprey responding to acute stress upregulate circulating 11-deoxycortisol and glucose in the blood plasma; (ii) only treatment with 11-deoxycortisol (and not deoxycorticosterone) increases plasma glucose; and (iii) among other tissues, the kidney uniquely expresses the transcriptional markers of steroidogenesis. Finally, in Chapter 7, I investigate the osmoregulatory capacity of post-metamorphic juvenile sea lamprey throughout springtime water warming and assess thermal tolerance of juvenile sea lamprey. I report that (i) elevated levels of gill NKA activity and SW tolerance persist well into the spring; (ii) survival after SW entry in late-spring is affected by temperature; and (iii) that juvenile sea lamprey can tolerate temperatures above 30 °C but begin showing signs of thermal stress, such as upregulation of heat shock proteins, at temperatures below their critical thermal maximum. Taken together, this dissertation contributes a substantial body of work regarding mechanisms of epithelial ion transport and corticosteroid action in the most basal vertebrate group. This dissertation describes that a single endogenous corticosteroid, 11-deoxycortisol, has a critical role in promoting the development of osmo- and ionoregulatory mechanisms during metamorphosis that confer survival in SW. This work will be of interest to scientists from a range of disciplines including physiology, endocrinology, evolutionary biology, developmental biology, and ecology, as well as conservationists and managers working with sea lamprey
Calculation of Transactinide Homolog Isotope Production Reactions Possible with the Center for Accelerator Mass Spectrometry (CAMS) at Lawrence Livermore National Laboratory
The LLNL heavy element group has been investigating the chemical properties of the heaviest elements over the past several years. The properties of the transactinides (elements with Z > 103) are often unknown due to their low production rates and short half-lives, which require lengthy cyclotron irradiations in order to make enough atoms for statistically significant evaluations of their chemistry. In addition, automated chemical methods are often required to perform consistent and rapid chemical separations on the order of minutes for the duration of the experiment, which can last from weeks to months. Separation methods can include extraction chromatography, liquid-liquid extraction, or gas-phase chromatography. Before a lengthy transactinide experiment can be performed at an accelerator, a large amount of preparatory work must be done both to ensure the successful application of the chosen chemical system to the transactinide chemistry problem being addressed, and to evaluate the behavior of the lighter elemental homologs in the same chemical system. Since transactinide chemistry is literally performed on one single atom, its chemical properties cannot be determined from bulk chemical matrices, but instead must be inferred from the behavior of the lighter elements that occur in its chemical group and in those of its neighboring elements. By first studying the lighter group homologs in a particular chemical system, when the same system is applied to the transactinide element under investigation, its decay properties can be directly compared to those of the homologues, thereby allowing an inference of its own chemistry. The Center for Accelerator Mass Spectrometry (CAMS) at Lawrence Livermore National Laboratory (LLNL) includes a 1 MV Tandem accelerator, capable of accelerating light ions such as protons to energies of roughly 15 MeV. By using the CAMS beamline, tracers of transactinide homolog elements can be produced both for development of chemical systems and for evaluation of homolog chemical properties. CAMS also offers an environment for testing these systems 'online' by incorporating automated chemical systems into the beamline so that tracers can be created, transported, and chemically separated all on the shorter timescales required for transactinide experiments. Even though CAMS is limited in the types and energies of ions they can accelerate, there are still a wide variety of reactions that can be performed there with commercially available target materials. The half-lives of these isotopes vary over a range that could be used for both online chemistry (where shorter half-lives are required) and benchtop tracers studies (where longer lived isotopes are preferred). In this document, they present a summary of tracer production reactions that could be performed at CAMS, specifically for online, automated chemical studies. They are from chemical groups four through seven, 13, and 14, which would be appropriate for studies of elements 104-107, 113, and 114. Reactions were selected that had (a) commercially available target material, (b) half-lives long enough for transport from a target chamber to an automated chemistry system, and (c) cross-sections at CAMS available projectile energies that were large enough to produce enough atoms to result in a statistically relevant signal after losses for transport and chemistry were considered. In addition, the resulting product atoms had to decay with an observable gamma-ray using standard Ge gamma-ray detectors. The table includes calculations performed for both metal targets and their corresponding oxides
Analysis of Cognitive Deficits of Concussion Patients: Dual Task, Motor Cognition, and Memory
The severity of a concussion is determined by the magnitude of the force of impact and the symptoms expressed post-injury. The most current and widely used test to identify a concussion in college athletics is called the Immediate Post Concussion Assessment and Cognitive Testing (ImPACT). It is a computerized neurocognitive test battery that measures different cognitive abilities and compares baseline with post-injury results. In the current study we formulated a series of physical and psychological cognition tests that measure similar cognitive abilities as the ImPACT. The purpose of this study is to demonstrate that physical tests paired with neurocognitive tests are a better determinate of post-concussion symptoms in athletes than a sedentary neurocognitive battery test alone. Such tests included balance, memory, spatial relations, attention and reaction time. Three different groups of post-concussed history were statistically compared. Group one (controls), consisted of participants with no previous history of a concussion (n=32). Group two (concussed), consisted of participants with a concussion in the past three months and who had recently been cleared to resume full sports activities (n=11). Group three (multiple concussed), consisted of participants with at least five concussions in their lifespan (n=7). A one-way ANOVA and two-tailed independent t-test were ran to observe any differences in tests between groups (
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Electron-capture delayed fission properties of neutron-deficient einsteinium nuclei
Electron-capture delayed fission (ECDF) properties of neutron-deficient einsteinium isotopes were investigated using a combination of chemical separations and on-line radiation detection methods. {sup 242}Es was produced via the {sup 233}U({sup 14}N,5n){sup 242}Es reaction at a beam energy of 87 MeV (on target) in the lab system, and was found to decay with a half-life of 11 {+-} 3 seconds. The ECDF of {sup 242}Es showed a highly asymmetric mass distribution with an average pre-neutron emission total kinetic energy (TKE) of 183 {+-} 18 MeV. The probability of delayed fission (P{sub DF}) was measured to be 0.006 {+-} 0.002. In conjunction with this experiment, the excitation functions of the {sup 233}U({sup 14}N,xn){sup 247{minus}x}Es and {sup 233}U({sup 15}N,xn){sup 248{minus}x}Es reactions were measured for {sup 243}Es, {sup 244}Es and {sup 245}Es at projectile energies between 80 MeV and 100 MeV
Higgs Sector in Extensions of the MSSM
Extensions of the Minimal Supersymmetric Standard Model (MSSM) with
additional singlet scalar fields solve the important mu-parameter fine tuning
problem of the MSSM. We compute and compare the neutral Higgs boson mass
spectra, including one-loop corrections, of the following MSSM extensions:
Next-to-Minimal Supersymmetric Standard Model (NMSSM), the nearly-Minimal
Supersymmetric Standard Model (nMSSM), and the U(1)'-extended Minimal
Supersymmetric Standard Model (UMSSM) by performing scans over model
parameters. We find that the Secluded U(1)'-extended Minimal Supersymmetric
Standard Model (sMSSM) is identical to the nMSSM if three of the additional
scalars decouple. The dominant part of the one-loop corrections are
model-independent since the singlet field does not couple to MSSM particles
other than the Higgs doublets. Thus, model-dependent parameters enter the
masses only at tree-level. We apply constraints from LEP bounds on the Standard
Model and MSSM Higgs boson masses and the MSSM chargino mass, the invisible Z
decay width, and the Z-Z' mixing angle. Some extended models permit a Higgs
boson with mass substantially below the SM LEP limit or above theoretical
limits in the MSSM. Ways to differentiate the models via masses, couplings,
decays and production of the Higgs bosons are discussed.Comment: 65 pages, 15 figures. Figure replaced and typos corrected. Version to
appear in Phys. Rev.
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