A series of small- to moderate-sized earthquakes occurred in Arkansas, Oklahoma and Texas from 2010 to 2012, coinciding with the arrival of the EarthScope Transportable Array (TA). The data the TA recorded from those earthquakes provide a unique opportunity to study attenuation of the Lg phase in the mid-continent and Gulf Coastal region. The TA data reveal previously unrecognized regional variability of ground motion propagation in the central United States. A study of the Fourier amplitude spectra shows the Lg phase exhibiting strong attenuation for ray paths from Arkansas, southwest through the Ouachita Orogenic Belt and into central Texas, and south into the Gulf Coastal region. Less attenuation is seen in central Texas for ray paths extending directly south from Oklahoma, though attenuation remains strong along the Gulf Coast. In contrast, ray paths to the north, regardless of source location, exhibit very little attenuation, especially in northern Missouri and southern Iowa. Regression models that incorporate near-receiver (distance-independent) attenuation due to thick sediments in the Gulf Coastal Plain successfully reduce path-related bias in the regression residuals for stations near the Gulf Coast. Dividing the central United States into three regions (the Gulf Coastal Plain, the Great Plains and the Midwest) further reduced bias, and allowed for the development of Q models in the Gulf Coastal Plain and the Great Plains. In the Gulf Coastal Plain, the Q model for that part of the ray path through the basement, from the earthquake to the base of the sediment deposits below the receiver, was found to be Q=(295±11)*f^(0.645±0.029). The model for attenuation in the sediment section near the receiver in the Gulf Coastal Plain is Q=(72±6.7)*f^(0.32±0.06) (velocity through the sediments is unconfirmed but thought to be approximately 1 km/s). The Q model for the Great Plains is  Q=(692±61.3)*f^(0.43±0.07). The Midwest region exhibited extremely complicated behavior: the data indicate little or no attenuation of amplitudes in the frequency band from approximately 0.7 to 2.0 Hz. As a consequence, Q in the Midwest region in that frequency range could not be realistically determined. / Master of Science

The false discovery rate (FDR) introduced by Benjamini and Hochberg (1995) is perhaps the most standard error controlling measure being used in a wide variety of applications involving multiple hypothesis testing. There are two approaches to control the FDR - the fixed error rate approach of Benjamini and Hochberg (BH, 1995) where a rejection region is determined with the FDR below a fixed level and the estimation based approach of Storey (2002) where the FDR is estimated for a fixed rejection region before it is controlled. In this proposal, we concentrate on both these approaches and propose new, improved versions of some FDR controlling procedures available in the literature. A number of adaptive procedures have been put forward in the literature, each attempting to improve the method of Benjamini and Hochberg (1995), the BH method, by incorporating into this method an estimate of number true null hypotheses. Among these, the method of Benjamini, Krieger and Yekutieli (2006), the BKY method, has been receiving lots of attention recently. In this proposal, a variant of the BKY method is proposed by considering a different estimate of number true null hypotheses, which often outperforms the BKY method in terms of the FDR control and power. Storey's (2002) estimation based approach to controlling the FDR has been developed from a class of conservatively biased point estimates of the FDR under a mixture model for the underlying p-values and a fixed rejection threshold for each null hypothesis. An alternative class of point estimates of the FDR with uniformly smaller conservative bias is proposed under the same setup. Numerical evidence is provided to show that the mean squared error (MSE) is also often smaller for this new class of estimates. Compared to Storey's (2002), the present class provides a more powerful estimation based approach to controlling the FDR. / Statistics

The large thermal cross section of cadmium makes it ideal for many practical applications where screening of thermal neutrons is desired. For example, in non-destructive assay techniques, or for astrophysical studies of the s-process. All such applications require precise knowledge of the neutron-capture cross section on cadmium. Although there are some data on neutron-capture cross sections particularly at thermal energies and at energies relevant for astrophysics, there is very little data at most other energies. Further, the evaluated cross sections from the ENDF and JENDL databases disagree at high energies. Therefore, there is a critical need for precise knowledge of the 114Cd(n, gamma)115Cd cross section over a large range of incident neutron energies. We performed a direct measurement of the neutron-capture cross section at the Los Alamos Neutron Science Center (LANSCE) using the Detector for Advanced Neutron Capture Experiments (DANCE). A highly enriched (∼$99%), 100 mg pressed metallic pellet sample of 114Cd was used to perform the neutron-capture measurements in the range of 1 eV to 300 keV using the white neutron source available at LANSCE. Additional neutron capture data were also taken on highly enriched samples of 112Cd and 113Cd to enable careful background subtraction of even the small contaminants found in the 114Cd sample. We used a large energy sum windows around the Q-value to circumvent any complication that may arise from populating the 180 keV isomeric (T1/2 = 44.56d) state in 115Cd.

Les réactions de fusion-évaporation et de transfert de nucléons entre ions lourds à des énergies proches de la barrière de Coulomb jouent un rôle essentiel dans l’étude de la structure nucléaire et des mécanismes de réaction. Dans le cadre de cette thèse, deux expériences de fusion-évaporation et de transfert de nucléons ont été réalisées au Laboratoire National de Legnaro en Italie : 40Ca+58Ni et 40Ca+64Ni. Dans une première expérience, les sections efficaces de fusion de 40Ca+58,64Ni ont été mesurées à des énergies au-dessus et en dessous de la barrière de Coulomb et ont été interprétées à l’aide de calculs en voies couplées et Hartree-Fock dépendants du temps (TDHF). Les résultats montrent l’importance de l’excitation à un phonon octupolaire dans le noyau 40Ca et les excitations à un phonon quadripolaire dans les noyaux 58Ni et 64Ni, ainsi que l’importance des voies de transfert de nucléons dans le système riche en neutrons 40Ca+64Ni. Dans une expérience complémentaire, les probabilités de transfert de nucléons de 40Ca+58,64Ni ont été mesurées dans le même domaine d’énergie que l’expérience précédente et ont été interprétées en effectuant des calculs TDHF+BCS. Les résultats confirment l’importance des voies de transfert de nucléons dans 40Ca+64Ni. Une description conjointe des probabilités de transfert de nucléons et des sections efficaces de fusion a été réalisée pour les deux réactions étudiées en utilisant une approche en voies couplées. / Heavy-ion fusion-evaporation and nucleon transfer reactions at energies close to the Coulomb barrier play an essential role in the study of nuclear structure and reaction dynamics. In the framework of this PhD thesis, two fusion-evaporation and nucleon transfer experiments have been performed at the Laboratori Nazionali di Legnaro in Italy : 40Ca+58Ni and 40Ca+64Ni. In a first experiment, fusion cross sections for 40Ca+58,64Ni have been measured from above to below the Coulomb barrier and have been interpreted by means of coupled-channels and Time-Dependent Hartree-Fock (TDHF) calculations. The results show the importance of the one-phonon octupole excitation in the 40Ca nucleus and the one-phonon quadrupole excitations in the 58Ni and 64Ni nuclei, as well as the importance of the nucleon transfer channels in the neutron-rich system 40Ca+64Ni. In a complementary experiment, nucleon transfer probabilities for 40Ca+58,64Ni have been measured in the same energy region as the previous experiment and have been interpreted by performing TDHF+BCS calculations. The results confirm the importance of nucleon transfer channels in 40Ca+64Ni. A simultaneous description of the nucleon transfer probabilities and the fusion cross sections has been performed for both reactions, using a coupled-channels approach.