Efficient analysis and representation of geophysical processes using localized spherical basis functions

While many geological and geophysical processes such as the melting of icecaps, the magnetic expression of bodies emplaced in the Earth's crust, or the surface displacement remaining after large earthquakes are spatially localized, many of these naturally admit spectral representations, or they may need to be extracted from data collected globally, e.g. by satellites that circumnavigate the Earth. Wavelets are often used to study such nonstationary processes. On the sphere, however, many of the known constructions are somewhat limited. And in particular, the notion of `dilation' is hard to reconcile with the concept of a geological region with fixed boundaries being responsible for generating the signals to be analyzed. Here, we build on our previous work on localized spherical analysis using an approach that is firmly rooted in spherical harmonics. We construct, by quadratic optimization, a set of bandlimited functions that have the majority of their energy concentrated in an arbitrary subdomain of the unit sphere. The `spherical Slepian basis' that results provides a convenient way for the analysis and representation of geophysical signals, as we show by example. We highlight the connections to sparsity by showing that many geophysical processes are sparse in the Slepian basis.Comment: To appear in the Proceedings of the SPIE, as part of the Wavelets XIII conference in San Diego, August 200

Scattered M3–4 Slip Bursts Within Creep Events on the San Andreas Fault

Scientists have observed the surface expression of creep events along the San Andreas Fault since the 1960s. However, the evolution of slip at depth has been examined relatively little. So here we probe that deep slip by analyzing strain observations just before and during hours‐ to day‐long creep events at the northern end of the creeping section of the San Andreas Fault. We identify 71 strain offsets that are likely produced by few‐hour bursts of slip at depth. Then, we grid search to determine the location, depth, and magnitude of these slip bursts. We find that the slip bursts occur at a range of along‐strike locations, from 0 to 7 km away from the surface slip observations. Slip occurs at depths from 0 to 10 km; 42%–55% of the bursts are likely below 4 km depth. The bursts typically have moments equivalent to M w 3.2–4.1 earthquakes. These findings suggest that creep events are not just small shallow events; they are relatively large events that nucleate at significant depths and could play a prominent role in the slip dynamics of the creeping section

A Method for Calibration of the Local Magnitude Scale Based on Relative Spectral Amplitudes, and Application to the San Juan Bautista, California, Area

We develop and use a spectral empirical Green’s function approach to estimate the relative source amplitudes of earthquakes near San Juan Bautista, California. We isolate the source amplitudes from path effects by comparing the recorded spectra of pairs of events with similar location and focal mechanism, without computing the path effect. With this method, we estimate the relative moments of 1600 M 1.5–4 local earthquakes, and we use these moments to recalibrate the duration magnitude scale in this region. The estimated moments of these small earthquakes increase with catalog magnitude M_D roughly proportionally to 10^(1.1M_D), slightly more slowly than a moment‐magnitude scaling of 10^(1.5M_w). This more accurate magnitude scaling can be used in analyses of the local earthquakes, such as comparisons between the seismic moments and geodetic observations

A Method for Calibration of the Local Magnitude Scale Based on Relative Spectral Amplitudes, and Application to the San Juan Bautista, California, Area

We develop and use a spectral empirical Green’s function approach to estimate the relative source amplitudes of earthquakes near San Juan Bautista, California. We isolate the source amplitudes from path effects by comparing the recorded spectra of pairs of events with similar location and focal mechanism, without computing the path effect. With this method, we estimate the relative moments of 1600 M 1.5–4 local earthquakes, and we use these moments to recalibrate the duration magnitude scale in this region. The estimated moments of these small earthquakes increase with catalog magnitude M_D roughly proportionally to 10^(1.1M_D), slightly more slowly than a moment‐magnitude scaling of 10^(1.5M_w). This more accurate magnitude scaling can be used in analyses of the local earthquakes, such as comparisons between the seismic moments and geodetic observations

Study of the Halogen Bonding between Pyridine and Perfluoroalkyl Iodide in Solution Phase Using the Combination of FTIR and 19

Halogen bonding between pyridine and heptafluoro-2-iodopropane (iso-C3F7I)/heptafluoro-1-iodopropane (1-C3F7I) was studied using a combination of FTIR and 19F NMR. The ring breathing vibration of pyridine underwent a blue shift upon the formation of halogen bonds with both iso-C3F7I and 1-C3F7I. The magnitudes of the shifts and the equilibrium constants for the halogen-bonded complex formation were found to depend not only on the structure of the halocarbon, but also on the solvent. The halogen bond also affected the Cα-F (C-F bond on the center carbon) bending and stretching vibrations in iso-C3F7I. These spectroscopic effects show some solvent dependence, but more importantly, they suggest the possibility of intermolecular halogen bonding among iso-C3F7I molecules. The systems were also examined by 19F NMR in various solvents (cyclohexane, hexane, chloroform, acetone, and acetonitrile). NMR dilution experiments support the existence of the intermolecular self-halogen bonding in both iso-C3F7I and 1-C3F7I. The binding constants for the pyridine/perfluoroalkyl iodide halogen bonding complexes formed in various solvents were obtained through NMR titration experiments. Quantum chemical calculations were used to support the FTIR and 19F NMR observations

Pluralism about Knowledge

In this paper I consider the prospects for pluralism about knowledge, that is, the view that there is a plurality of knowledge relations. After a brief overview of some views that entail a sort of pluralism about knowledge, I focus on a particular kind of knowledge pluralism I call standards pluralism. Put roughly, standards pluralism is the view that one never knows anything simpliciter. Rather, one knows by this-or-that epistemic standard. Because there is a plurality of epistemic standards, there is a plurality of knowledge relations. In §1 I argue that one can construct an impressive case for standards pluralism. In §2 I clarify the relationship between standards pluralism, epistemic contextualism and epistemic relativism. In §3 I argue that standards pluralism faces a serious objection. The gist of the objection is that standards pluralism is incompatible with plausible claims about the normative role of knowledge. In §4 I finish by sketching the form that a standards pluralist response to this objection might take

Undergraduate nursing and midwifery student’s attitudes to mental illness

AimTo explore levels of stigma in students of all fields of nursing and midwifery at different years, and examine the impact of exposure to people with mental illness.DesignA cross-sectional survey was used.MethodsThe Community Attitudes to Mental Illness questionnaire was administered to all branches of student nurses (adult health, mental health, child health and learning disability) and midwives in all three years in one Higher Education Institution (HEI) in Scotland.ResultsMental health nursing students scored significantly better on all stigma sub scales. Stigma worsened with a little professional exposure to people with mental illness but then improved with increasing exposure. Both personal and professional exposure to people with mental illness changes perceptions. The professional results follow a J-curve. Current plans for cross field experience involving short or virtual placements during student nurse training are likely to worsen stigma rather than improve it

Old Jokes, New Media – Online Sexism and Constructions of Gender in Internet Memes

The Internet is a space where the harassment of women and marginalised groups online has attracted the attention of both academic and popular press. Feminist research has found that instances of online sexism and harassment are often reframed as “acceptable” by constructing them as a form of humour. Following this earlier research, this present paper explores a uniquely technologically-bound type of humour by adopting a feminist, social-constructionist approach to examine the content of popular Internet memes. Using thematic analysis on a sample of 240 image macro Internet memes (those featuring an image with a text caption overlaid), we identified two broad, overarching themes – Technological Privilege and Others. Within the analysis presented here, complex and troubling constructions of gendered identity in online humour are explored, illustrating the potential for the othering and exclusion of women through humour in technological spaces. We argue that this new iteration of heteronormative, hegemonic masculinity in online sexism, couched in “irony” and “joking”, serves to police, regulate and create rightful occupants and owners of such spaces

Community-based screening and triage connecting First Nations children and youth to local supports: a cross-sectional study

BACKGROUND: First Nations children in Canada experience health inequities. We aimed to determine whether a self-report health app identified children's needs for support earlier in their illness than would typically occur. METHODS: Children (aged 8 to 18 yr) were recruited from a rural First Nation community. Children completed the Aaniish Naa Gegii: the Children's Health and Well-being Measure (ACHWM) and then met with a local mental health worker who determined their risk status. ACHWM Emotional Quadrant Scores (EQS) were compared between 3 groups of children: healthy peers (HP) who were not at risk, those with newly identified needs (NIN) who were at risk and not previously identified, and a typical treatment (TT) group who were at risk and already receiving support. RESULTS: We included 227 children (57.1% girls), and the mean age was 12.9 (standard deviation [SD] 2.9) years. The 134 children in the HP group had a mean EQS of 80.1 (SD 11.25), the 35 children in the NIN group had a mean EQS of 67.2 (SD 13.27) and the 58 children in the TT group had a mean EQS of 66.2 (SD 16.30). The HP group had significantly better EQS than the NIN and TT groups (p < 0.001). The EQS did not differ between the NIN and TT groups (p = 0.8). INTERPRETATION: The ACHWM screening process identified needs for support among 35 children, and the associated triage process connected them to local services; the similarity of EQS in the NIN and TT groups highlights the value of community screening to optimize access to services. Future research will examine the impact of this process over the subsequent year in these groups