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Search Results: 1 - 10 of 9834 matches for " Patrick Treuthardt "
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Determination of resonance locations in barred spiral galaxies using multiband photometry
Amber D. Sierra,Marc S. Seigar,Patrick Treuthardt,Ivanio Puerari
Physics , 2015, DOI: 10.1093/mnras/stv678
Abstract: In this paper, we apply a method identified by Puerari & Dottori (1997) to find the corotation radii (CR) in spiral galaxies. We apply our method to 57 galaxies, 17 of which have already have their CR locations determined using other methods. The method we adopted entails taking Fourier transforms along radial cuts in the u, g, r, i, and z wavebands and comparing the phase angles as a function of radius between them. The radius at which the phase angles cross indicates the location of the corotation radius. We then calculated the relative bar pattern speed, $\mathcal{R}$, and classified the bar as "fast", where $\mathcal{R} < 1.4$, slow, where $\mathcal{R} \geq 1.4$, or intermediate, where the errors on $\mathcal{R}$ are consistent with the bar being "slow" or "fast". For the 17 galaxies that had their CR locations previously measured, we found that our results were consistent with the values of $\mathcal{R}$ obtained by the computer simulations of Rautiainen, Salo & Laurikainen (2008). For the larger sample, our results indicate that 34 out of 57 galaxies (~60%) have fast bars. We discuss these results in the context of its implications for dark matter concentrations in disk galaxies. We also discuss these results in the context of different models for spiral structure in disk galaxies.
On the Link Between Central Black Holes, Bar Dynamics, and Dark Matter Halos in Spiral Galaxies
Patrick Treuthardt,Marc S. Seigar,Amber D. Sierra,Ismaeel Al-Baidhany,Heikki Salo,Daniel Kennefick,Julia Kennefick,Claud H. S. Lacy
Physics , 2012, DOI: 10.1111/j.1365-2966.2012.21118.x
Abstract: The discovery of a relationship between supermassive black hole (SMBH) mass and spiral arm pitch angle (P) is evidence that SMBHs are tied to the overall secular evolution of a galaxy. The discovery of SMBHs in late-type galaxies with little or no bulge suggests that an underlying correlation between the dark matter halo concentration and SMBH mass (MBH) exists, rather than between the bulge mass and MBH. In this paper we measure P using a two-dimensional fast fourier transform and estimate the bar pattern speeds of 40 barred spiral galaxies from the Carnegie-Irvine Galaxy Survey. The pattern speeds were derived by estimating the gravitational potentials of our galaxies from Ks-band images and using them to produce dynamical simulation models. The pattern speeds allow us to identify those galaxies with low central dark halo densities, or fast rotating bars, while P provides an estimate of MBH. We find that a wide range of MBH exists in galaxies with low central dark matter halo densities, which appears to support other theoretical results. We also find that galaxies with low central dark halo densities appear to follow more predictable trends in P versus de Vaucouleurs morphological type (T) and bar strength versus T than barred galaxies in general. The empirical relationship between MBH and total gravitational mass of a galaxy (Mtot) allows us to predict the minimum Mtot that will be observationally measured of our fast bar galaxies. These predictions will be investigated in a subsequent paper.
Ego Depletion and the Humean Theory of Motivation  [PDF]
Patrick Fleming
Open Journal of Philosophy (OJPP) , 2014, DOI: 10.4236/ojpp.2014.43042
Abstract:

By what capacities do human beings engage in intentional action? Humeans about motivation claim that the source of all action is desire. Volitionalists claim that action has two distinct sources, one in the will and one in desire. Recent work suggests that volitionalism has some empirical support. Roy F. Baumeister and colleagues have argued for a phenomenon called “ego depletion”. They argue that some aspect of the self exerts volition in a number of different contexts. The main evidence for this claim is that experimental subjects who engage in acts of self-regulation are less likely to engage in similar actions on later tests. The evidence calls for a reformulation of the Humean theory, not a rejection of it. And the reformulation is one that still has interest for metaethics. Many philosophers are interested in the Humean theory of motivation because they believe that it has implications for the correct theory of normative practical reasons. Here I argue that if the Humean theory of motivation was ever a threat to the objectivity of morality, it still is.

Letter to Editor  [PDF]
Patrick Velte
Open Journal of Business and Management (OJBM) , 2014, DOI: 10.4236/ojbm.2014.21001
Abstract: Letter to Editor
Rain Attenuation Effects on 2.6 GHz WiMAX Networks Deployment in Ghana  [PDF]
Patrick Fiati
World Journal of Engineering and Technology (WJET) , 2015, DOI: 10.4236/wjet.2015.33009
Abstract: WiMAX communication systems operating at 2.6 G frequencies are used for broadband multimedia and internet based services. At these frequencies, the signal will be affected by various propagation impairments such as rain attenuation, cloud attenuation, tropospheric scintillation, ionospheric scintillation, water vapour attenuation, and rain and ice depolarization. Among all the pro-pagation impairments, rain attenuation is the most important and critical parameter. In this research, rain attenuation is calculated at KNUST, Kumasi using ITU-R rain attenuation model. The preliminary results of the work will be used to calculate the attenuation experimentally and comparison can be made, which helps to develop a new rain attenuation model at 2.6 G bands. Rain attenuation is an important aspect of signal propagation above 2.6 GHz frequency. The attenuation time series generation from point rain rate measurement is crucial due to unavailability of actual signal measurements. In this research, a simple and realistic approach has been demonstrated for better estimation of rain attenuation using WiMAX-band signal propagation data and ground rain rate measurements in Ghana. The ITU-R model of rain attenuation has been modified by incorporating an effective slant path model. The effective slant path has been estimated and modeled in terms of a power-law relationship of rain rate data of 2007-2008. The methodology has been validated with the measured data of 2014. Comparison with ITU-R and GMET clearly demonstrates the improved predictability of the proposed model at the present tropical location.
RapidSCAT Sigma-0 and Tb Measurements Validation  [PDF]
Patrick Fiati
World Journal of Engineering and Technology (WJET) , 2016, DOI: 10.4236/wjet.2016.42017
Abstract: Scatterometer Radar Backscatter Calibration since the first SeaSat-A Satellite Scatterometer (Birer et al., 1982), the Amazon tropical rain forest has been recognized as a spatially large extent, homogeneous radar calibration target. During the commissioning of NSCAT (1996) and later QuikSCAT (1999), CFRSL worked with the JPL Scatterometer Cal/Val team to perform normalized radar cross section (Sigma-0) calibrations using the Amazon (see Zec et al., 1999-A and 1999-B) [1]. It is important to continue this activity using RapidSCAT to validate the Sigma-0 measurement provided in the L-1A data product, and moreover the time series of these backscatter observations can be used to establish an improved Ku-band Amazon calibration site for future on-orbit radar calibration [2]. Unfortunately, the Amazon radar backscatter (Sigma-0) exhibits a time of day dependence that is not well characterized, and for the sun-synchronous polar orbiting satellites (SeaSat-A, ADEOS-I and QuikSCAT), the observations occur at specific times of day, during the morning and night passes. But now with the low-earth-orbit of the ISS, there will be an orderly orbit precession, which allows the region to be uniformly sampled over the 24-hour period [3]. Also, since the RapidSCAT employs a conical scanning geometry, we can examine the isotropic nature of Amazon backscatter established by Zec’s (1998-A) analysis of NSCAT and later (1999-B) of QuikSCAT observations [4]. Thus, observations, collected over the RapidSCAT two-year mission will sample the Amazon with high spatial/temporal resolution, as a function of time of day, and over seasons. We propose to analyze these data to develop a high spatial resolution Sigma-0 Amazon map that can be used by future satellite radar missions.
Association between Cardiovascular Disease Risk Factor Knowledge and Lifestyle  [PDF]
Patrick Mullie, Peter Clarys
Food and Nutrition Sciences (FNS) , 2011, DOI: 10.4236/fns.2011.210140
Abstract: Objective: To relate cardiovascular risk factor knowledge to lifestyle. Methods: In this cross-sectional study, food consumption and lifestyle characteristics were recorded using mailed questionnaires. The dietary pattern was described using the Mediterranean Diet Score (MDS). An open ended questionnaire without predefined choices or answers was used to capture cardiovascular knowledge. Results: Lack of physical activity, smoking and eating too much fat were the 3 most cited potential cardiovascular risk factors, while being overweight, eating too much salt and a low consumption of fruits and vegetables were the least cited risk factors. Age, Body Mass Index, physical activity, smoking, income and dietary habits were not consistently associated with knowledge of risk factors. A low socioeconomic position as measured by the indicator education was associated with a lower knowledge of established and modifiable cardiovascular risk factors. Conclusions: Risk factor knowledge, an essential step in prevention of CVD, is not systematically associated with a healthier lifestyle. The findings of this study confirm that there is a gap between risk factor knowledge and lifestyle.
Site Specific Uncertainty in Regional Haze RuleHaze Indexes  [PDF]
Patrick A. Ryan
Atmospheric and Climate Sciences (ACS) , 2012, DOI: 10.4236/acs.2012.21001
Abstract: In 1999, the US Environmental Protection Agency (EPA) published the regional haze rule (RHR). The RHR default implementation plan calls for each class I area 20% worst baseline (2000-2004) visibility to improve linearly in time to natural conditions in 2064 and in calendar year 2018, each class I area 20% worst visibility is to comply with the 2018 visibility that falls on the linear improvement glide path from baseline (2000-2004) to natural (2064) conditions. This study shows that accurately assessing compliance depends on assessing the uncertainty in baseline, natural and 2018 visibility estimates. This study identifies ±3 dV and ±4 dV of uncertainty in 20% worst natural and baseline visibility estimates. The percent uncertainty in calculated 2018 glide path visibility values ranges from 10% - 45%.
Leaf Wand for Measuring Chlorophyll Fluorescence on Cylindrical Leaves and Its Application on Juncus roemerianus (Black Needlerush)  [PDF]
Patrick D. Biber
American Journal of Plant Sciences (AJPS) , 2012, DOI: 10.4236/ajps.2012.31007
Abstract: Chlorophyll fluorescence is a well established technique to rapidly and non-invasively determine photosynthesis parameters in plant leaves. It can be used in both laboratory and field settings, and frequently dark-adaptation of a leaf sample is called for. In the field, this can be accomplished on flat leaves using standard leaf clips supplied by instrument manufacturers. However, not all plant leaves are flat, many are cylindrical or otherwise three-dimensional in shape. The standard leaf clip does not close fully on three-dimensional leaves, therefore, does not allow the sample to be properly dark adapted in the field. A new leaf “wand” was developed that can be slipped over an entire cylindrical leaf or culm of rushes and sedges for both light- and dark-adapted measurements. This new leaf wand is compared to the standard leaf clip (DLC-8) using a Walz mini-PAM on Juncus roemerianus(Black needlerush). Results indicate that dark-adapted yield measurements are not significantly different between leaf clips, while light-adapted yields are higher with the leaf wand. The potential sources of difference in the optical path of the excitation light and fluorescence return are discussed and compared between leaf clips. Construction of specialized leaf wands should be considered for any leaves are not flat and therefore that do not fit the standard leaf clip for complete dark-adaptation under field conditions.
Limited Re-Sequencing for Mixed-Models with Multiple Objectives, Part II: A Permutation Approach  [PDF]
Patrick R. McMullen
American Journal of Operations Research (AJOR) , 2012, DOI: 10.4236/ajor.2012.21002
Abstract: This research presents an approach to solving the limited re-sequencing problem for a JIT system when two objectives are considered for multiple processes. One objective is to minimize the number of setups; the other is to minimize the material usage rate [1]. For this research effort, each unique permutation of the problem’s demand structure is noted, and used as a mechanism for finding subsequent sequences. Two variants of this permutation approach are used: one employs a Monte-Carlo simulation, while the other employs a modification of Ant-Colony Optimization to find sequences satisfying the objectives of interest. Problem sets from the literature are used for assessment, and experimentation shows that the methodology presented here outperforms methodology from an earlier research effort [3].
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