A review of the benefits and applications of the thorium fuel cycle

This paper aims to inform the reader of the benefits that can be achieved by using thorium as a fuel for nuclear power. Stages of the thorium cycle are directly compared against the current uranium based nuclear fuel cycle. These include mining, milling, fuel fabrication, use of various reactor designs, reprocessing, and disposal. Thorium power promises several key advantages over traditional nuclear power methods, namely a dramatic decrease in long lived radioactive waste, increased fuel efficiency, greater chemical stability during disposal, and higher adaptability for differing reactor designs across a wider range of the thermal neutron spectrum. Obstacles that face the thorium fuel cycle are the necessity for remote and automated reprocessing, build up of neutron poisoning and long lived 233Pa in the decay chain during operation, and a large logistical shift in the way the nuclear power industry operates. By combining the thorium fuel cycle with molten salt reactor technology, the first two challenges are mitigated due to the simple reprocessing associated with the novel idea of a liquid based reactor core. Hence, an increase in public demand for thorium power will be necessary to persuade key players in the nuclear industry that the switch to thorium will be economical

Some Observations Pertaining to the Effects of Relaxin Upon the Bovine

The process of birth normally follows a set pattern. The main steps in chronological order are: labor, opening of the cervix, and delivering the young. The cervix serves an important function in reproduction. The cervix is the constricted portion separating the uterus and the vagina, and consists primarily of thick connective tissues especially constructed in folds forming a hollow tube. Through the cervix passes sperm, menstrual debris and in pregnancy the newborn. During pregnancy a mucous plug forms in the cervix and keeps out foreign material and bacteria. In the non-pregnant cow the opening is small. The cervix opening is constricted enough so that difficulty in inserting an artificial insemination tube sometimes occurs. If ova transfer can be perfected to the degree that artificial insemination is today, a revolutionary way of up-breeding a herd of cattle may result. In order for ova transfer to fulfill this role a non-surgical method of extracting and implanting must be perfected. If a non-surgical method is to be used, entrance into the uterus through the cervix is paramount is to be used, entrance into the uterus through the cervix is paramount the non-surgical equipment used to collect the ova is considerably larger than an artificial inseminating tube. Passage through the cervix with this equipment is accomplish with extreme difficulty. The inaccessibility of the uterus resulting from constriction of the cervix has markedly hampered the development of ova transfer. If the cervix can be dilated so as to allow easy entrance into the uterus, ova transfer may become of practical value in the not too distant future. A dilated cervix would allow larger and more precise collecting instrument to be used. Parturition is facilitated in some rodents by the action of relaxin upon the symphysis pubis and pelvic bones. Relaxin is a female hormone secreted by the placenta, uterus and ovaries and is present in the blood during gestation of many animals. Relaxin apparently has two purposes in the human uterine quiescence during gestation and dilation of the cervix at parturition. The use of relaxin to dilate the cervix in human suggested the possibility that dilation of the bovine cervix may be obtained by the administration of relaxin. To further investigate the physiological properties of the cervix and the possibility of dilation in the non-pregnant cow, the following experiment were conducted. 1 The effect of relaxin upon the cow’s cervix while in estrus. 2 The effect of liquid and depot relaxin upon the cow’s cervix when primed with stilbestrol. 3 The effect of blood from a cow in labor, transfused into a non-pregnant, non-estrus recipient. The milk letdown response just prior to parturition suggests that the hormones probably are influential and effective at this time. Oxycontin is known to contract the alveolar and force milk into the collecting ducts, gland cisterns, and test sinuses. Relaxin is likewise believed to be present in quantity at parturition and might have a contraction effect on the myoeptithelium around the alveoli. To determine if such action might be possible in the lactating cow, a series of experiments were conducted to determine the effect of relaxin on milk letdown

Development of advanced techniques for rotorcraft state estimation and parameter identification

An integrated methodology for rotorcraft system identification consists of rotorcraft mathematical modeling, three distinct data processing steps, and a technique for designing inputs to improve the identifiability of the data. These elements are as follows: (1) a Kalman filter smoother algorithm which estimates states and sensor errors from error corrupted data. Gust time histories and statistics may also be estimated; (2) a model structure estimation algorithm for isolating a model which adequately explains the data; (3) a maximum likelihood algorithm for estimating the parameters and estimates for the variance of these estimates; and (4) an input design algorithm, based on a maximum likelihood approach, which provides inputs to improve the accuracy of parameter estimates. Each step is discussed with examples to both flight and simulated data cases

An adaptive scheme for the approximation of dissipative systems

We propose a new scheme for the long time approximation of a diffusion when the drift vector field is not globally Lipschitz. Under this assumption, regular explicit Euler scheme --with constant or decreasing step-- may explode and implicit Euler scheme are CPU-time expensive. The algorithm we introduce is explicit and we prove that any weak limit of the weighted empirical measures of this scheme is a stationary distribution of the stochastic differential equation. Several examples are presented including gradient dissipative systems and Hamiltonian dissipative systems

Thermodynamic Effects of the Hydrophobic Surfactant Proteins on the Early Adsorption of Pulmonary Surfactant

AbstractWe determined the influence of the two hydrophobic proteins, SP-B and SP-C, on the thermodynamic barriers that limit adsorption of pulmonary surfactant to the air–water interface. We compared the temperature and concentration dependence of adsorption, measured by monitoring surface tension, between calf lung surfactant extract (CLSE) and the complete set of neutral and phospholipids (N&PL) without the proteins. Three stages generally characterized the various adsorption isotherms: an initial delay during which surface tension remained constant, a fall in surface tension at decreasing rates, and, for experiments that reached ∼40 mN/m, a late acceleration of the fall in surface tension to ∼25 mN/m. For the initial change in surface tension, the surfactant proteins accelerated adsorption for CLSE relative to N&PL by more than ten-fold, reducing the Gibbs free energy of transition (ΔG0‡) from 119 to 112 kJ/mole. For the lipids alone in N&PL, the enthalpy of transition (ΔH0‡, 54 kJ/mole) and entropy (−T · ΔS0‡, 65 kJ/mole at 37°C) made roughly equal contributions to ΔG0‡. The proteins in CLSE had little effect on −T · ΔS0‡ (68 kJ/mole), but lowered ΔG0‡ for CLSE by reducing ΔH0‡ (44 kJ/mole). Models of the detailed mechanisms by which the proteins facilitate adsorption must meet these thermodynamic constraints

Protein secondary structure prediction from circular dichroism spectra using a self-organizing map with concentration correction

Collecting circular dichroism (CD) spectra for protein solutions is a simple experiment, yet reliable extraction of secondary structure content is dependent on knowledge of the concentration of the protein—which is not always available with accuracy. We previously developed a self-organizing map (SOM), called Secondary Structure Neural Network (SSNN), to cluster a database of CD spectra and use that map to assign the secondary structure content of new proteins from CD spectra. The performance of SSNN is at least as good as other available protein CD structure-fitting algorithms. In this work we apply SSNN to a collection of spectra of experimental samples where there was suspicion that the nominal protein concentration was incorrect. We show that by plotting the normalized root mean square deviation of the SSNN predicted spectrum from the experimental one versus a concentration scaling-factor it is possible to improve the estimate of the protein concentration while providing an estimate of the secondary structure. For our implementation (51 data points 240–190 nm in nm increments) good fits and structure estimates were obtained if the NRMSD (normalized root mean square displacement, RMSE/data range) is <0.03; reasonable for NRMSD <0.05; and variable above this. We also augmented the reference database with 100% helical spectra and truly random coil spectra

SSNN, a method for neural network protein secondary structure fitting using circular dichroism data

Circular dichroism (CD) spectroscopy is a quick method for measuring data that can be used to determine the average secondary structures of proteins, probe their interactions with their environment, and aid in drug discovery. This paper describes the operation and testing of a self-organising map (SOM) structure-fitting methodology named Secondary Structure Neural Network (SSNN), which is a methodology for estimating protein secondary structure from CD spectra of unknown proteins using CD spectra of proteins with known X-ray structures. SSNN comes in two standalone MATLAB applications for estimating unknown proteins' structures, one that uses a pre-trained map and one that begins by training the SOM with a reference set of the user's choice. These are available at http://www2.warwick.ac.uk/fac/sci/chemistry/research/arodger/arodgergroup/research_intro/instrumentation/ssnn/ as SSNNGUI and SSNN1_2 respectively. They are available for both Macintosh and Windows formats with two reference sets: one obtained from the CDPro website, referred to as CDDATA.48 which has 48 protein spectra and structures, and one with 53 proteins (CDDATA.48 with 5 additional spectra). Here we compare SSNN with CDSSTR, a widely-used secondary structure methodology, and describe how to use the standalone SSNN applications. Current input format is Δε per amino acid residue from 240 nm to 190 nm in 1 nm steps for the known and unknown proteins and a vector summarising the secondary structure elements of the known proteins. The format is readily modified to include input data with e.g. extended wavelength ranges or different assignment of secondary structures

State-dependent Neural Inhibition by Extracellular Stimulation

Utilizing the Aplysia california buccal ganglia neurons, our research built upon previous findings concerning the presence of neuronal activity states, but demonstrate that these states play a role in the cell’s responsiveness to electrical stimulation. It was demonstrated that fast-firing neurons are more resistant to inhibitory stimulation as compared to slow-firing neurons. NEURON computational modeling revealed differences in ion channel dynamics that may underlie the differences in stimulation responsiveness that are associated with neuronal states

Optical interferometer in space

The present design concepts for a Laser Gravitational Wave Observatory in Space are described. Laser heterodyne distance measurements are made between test masses located in three spacecraft separated by roughly 10(exp 6) km. The major technology issues are: the reduction of spurious acceleration noise for the test masses to below 2 x 10(exp -15) cm/sq sec/Hz(0.5) from 10(exp -5) to 10(exp -3) Hz; and the measurement of changes in the difference of the antenna arm lengths to 5 x 10(exp -11) cm/Hz(0.5) from 10(exp -3) to 1 Hz with high reliability. The science objectives are: to measure discrete sinusoidal gravitational wave signals from individual sources with periods of 1 second to 1 day; to measure the stochastic background due to unresolved binaries; and to search for gravitational wave pulses with periods longer than 1 sec from possible exotic sources such as gravitational collapse of very massive objects