5,873 research outputs found
Charged Vortex Dynamics in Ginzburg-Landau Theory of the Fractional Quantum Hall Effect
We write a Ginzburg-Landau Hamiltonian for a charged order parameter
interacting with a background electromagnetic field in 2+1 dimensions. Using
the method of Lund we derive a collective coordinate action for vortex defects
in the order parameter and demonstrate that the vortices are charged. We
examine the classical dynamics of the vortices and then quantize their motion,
demonstrating that their peculiar classical motion is a result of the fact that
the quantum motion takes place in the lowest Landau level. The classical and
quantum motion in two dimensional regions with boundaries is also investigated.
The quantum theory is not invariant under magnetic translations. Magnetic
translations add total time derivative terms to the collective action, but no
extra constants of the motion result.Comment: 28 pages + 1 Figure, new phyzzx macro (included), MAD/TH-92-0
Combining Machine Learning and Empirical Engineering Methods Towards Improving Oil Production Forecasting
Current methods of production forecasting such as decline curve analysis (DCA) or numerical simulation require years of historical production data, and their accuracy is limited by the choice of model parameters. Unconventional resources have proven challenging to apply traditional methods of production forecasting because they lack long production histories and have extremely variable model parameters. This research proposes a data-driven alternative to reservoir simulation and production forecasting techniques. We create a proxy-well model for predicting cumulative oil production by selecting statistically significant well completion parameters and reservoir information as independent predictor variables in regression-based models. Then, principal component analysis (PCA) is applied to extract key features of a well’s time-rate production profile and is used to estimate cumulative oil production. The efficacy of models is examined on field data of over 400 wells in the Eagle Ford Shale in South Texas, supplied from an industry database. The results of this study can be used to help oil and gas companies determine the estimated ultimate recovery (EUR) of a well and in turn inform financial and operational decisions based on available production and well completion data
AN HISTORICAL AND THEOLOGICAL SURVEY OF THE CATHOLIC DOCTRINE OF PREDESTINATION
It is our conviction that the reason the doctrine of predestination is largely avoided in Catholic circles/institutions is two-fold. First, it is not understood in its proper historical context as a Catholic doctrine, derived from the sources of revelation and explicated by virtually all of the great theologians of the Church. Instead, it is often seen in some Catholic circles as an anomaly of Reformed theology. Secondly, that there are two underlying theological errors which distort the doctrine itself: 1. That God is just one agent (albeit the most powerful one) among many in the universe. 2. That human liberty requires a radical autonomy, even from the very causal ground on which it stands. If one’s theological landscape does not include a proper understanding of divine providence and the creature’s dependence on God for every free act, whether natural or supernatural, then God’s predestination becomes an obstacle to freedom and an arbiter of mercy for some, and strict justice for most
Normalised Root Mean Square and Amplitude of Sidebands of Vibration Response as Tools for Gearbox Diagnosis
Quick assessment of the condition of gearboxes used in helicopters is a safety requirement. One of the most widely used helicopter on-board-mounted condition monitoring system these days is the Health and Usage Monitoring System. It has been specifically designed to monitor the condition of all safety-critical components operating in the helicopter through calculation of so-called condition indicators (CIs) - signal processing routines designed to output a single number that represents the condition of the monitored component. Among number of available parameters, there is a couple of CIs that over the years of testing have earned a reputation of being the most reliable measures of the gear tooth condition. At the same time, however, it has been observed that in some cases, those techniques do not properly indicate the deteriorating condition with the propagation of a gear tooth fault with the period of operation. Hence, three more robust methods have been suggested, which are discussed in this article
Malaria-filaria coinfection in mice makes malarial disease more severe unless filarial infection achieves patency
Coinfections are common in natural populations, and the literature suggests that helminth coinfection readily affects how the immune system manages malaria. For example, type 1–dependent control of malaria parasitemia might be impaired by the type 2 milieu of preexisting helminth infection. Alternatively, immunomodulatory effects of helminths might affect the likelihood of malarial immunopathology. Using rodent models of lymphatic filariasis (Litomosoides sigmodontis) and noncerebral malaria (clone AS Plasmodium chabaudi chabaudi), we quantified disease severity, parasitemia, and polyclonal splenic immune responses in BALB/c mice. We found that coinfected mice, particularly those that did not have microfilaremia (Mf), had more severe anemia and loss of body mass than did mice with malaria alone. Even when controlling for parasitemia, malaria was most severe in Mf coinfected mice, and this was associated with increased interferon-g responsiveness. Thus, in Mf mice, filariasis upset a delicate immunological balance in malaria infection and exacerbated malaria-induced immunopathology. Helminth infections are prevalent throughout tropical regions where malaria is transmitted [1–5]. Interactions among infections commonly alter disease severity [6, 7], and malaria-helminth coinfection can either exac
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Urethral Defect in Setting of Recurrent Urethral Foreign Body Insertion.
We present a case of recurrent episodes of foreign body insertion into the urethra, ultimately resulting in urethral defect at the penoscrotal junction. We have decided against treating the urethral defect as it facilitates nonoperative retrieval of the urethral foreign bodies. We present our experience and rationale for the clinical management of this complex patient
Twist Model Development and Results from the Active Aeroelastic Wing F/A-18 Aircraft
Understanding the wing twist of the active aeroelastic wing (AAW) F/A-18 aircraft is a fundamental research objective for the program and offers numerous benefits. In order to clearly understand the wing flexibility characteristics, a model was created to predict real-time wing twist. A reliable twist model allows the prediction of twist for flight simulation, provides insight into aircraft performance uncertainties, and assists with computational fluid dynamic and aeroelastic issues. The left wing of the aircraft was heavily instrumented during the first phase of the active aeroelastic wing program allowing deflection data collection. Traditional data processing steps were taken to reduce flight data, and twist predictions were made using linear regression techniques. The model predictions determined a consistent linear relationship between the measured twist and aircraft parameters, such as surface positions and aircraft state variables. Error in the original model was reduced in some cases by using a dynamic pressure-based assumption. This technique produced excellent predictions for flight between the standard test points and accounted for nonlinearities in the data. This report discusses data processing techniques and twist prediction validation, and provides illustrative and quantitative results
Simultaneous calculation of the helical pitch and the twist elastic constant in chiral liquid crystals from intermolecular torques
We present a molecular simulation method that yields simultaneously the equilibrium pitch wave number q and the twist elastic constant K2 of a chiral nematic liquid crystal by sampling the torque density. A simulation of an untwisted system in periodic boundary conditions gives the product K2q; a further simulation with a uniform twist applied provides enough information to separately determine the two factors. We test our new method for a model potential, comparing the results with K2q from a thermodynamic integration route, and with K2 from an order fluctuation analysis. We also present a thermodynamic perturbation theory analysis valid in the limit of weak chirality
An Optimal Control Framework to Address the Relationship between Water Resource Management and Water-Borne Health Impacts: Focus on the Texas Lower Rio Grande Valley
The objective of this study is develop a theoretical model that can evaluate two types of public health expenditures on water-borne health risks: water-related municipal services, an ex ante preventative measure against water-borne contamination, and medical treatment, an ex post treatment of the water-borne pollutant’s harmful effects on human health. The modeled community can allocate resources in either centralized-municipal water-services, point-of-use water-services, or medical intervention, with expenditures subject to a budget constraint. The movement of a water-borne illness through the community is modeled with a susceptible-infected-susceptible (SIS) disease framework. An optimization framework is developed, including a statement of the problem’s Hamiltonian and first-order-conditions. The first-order-conditions are discussed. Future work includes obtaining a numerical solution to the optimization problem.water, public health, rural development, dynamic optimization, Community/Rural/Urban Development, Resource /Energy Economics and Policy,
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