School and Community Expectations in a Small, Rural, Northern New Mexico School

School leaders find themselves in constant reflection of their academic ranking in a time of national reform. With the No Child Left Behind Act and Every Student Succeeds Act, expectations around school and student performance are created to compare against national standards. Rural communities have undergone significant social and economic changes due to the decline of family farms, accompanied by people leaving and closing of businesses all which have dramatic effects on rural schools (Petrin, et. al. 2014). With increased attention on academic achievement at the state and federal level, it is imperative that we understand how rural schools address these changes both in the communities and within the school. My research was designed to explore expectations of school professionals, community members, and students as make decisions to stay or leave their communities. This is an exploration and description of school and community expectations as well as student expectations of themselves. My study is designed to inform the rural school district and communities in this northern New México town as well as to inform rural educators and leaders in a larger context

Supersonic dislocations observed in a plasma crystal

Experimental results on the dislocation dynamics in a two-dimensional plasma crystal are presented. Edge dislocations were created in pairs in lattice locations where the internal shear stress exceeded a threshold and then moved apart in the glide plane at a speed higher than the sound speed of shear waves, $C_T$. The experimental system, a plasma crystal, allowed observation of this process at an atomistic (kinetic) level. The early stage of this process is identified as a stacking fault. At a later stage, supersonically moving dislocations generated shear-wave Mach cones

Effects of fault finiteness on near-source ground motion

Near-source ground motion at four azimuths but constant epicentral range is computed from a buried circular strike-slip fault in a half-space. Particle acceleration, velocity, and displacement at each station on the free surface is computed in the frequency band 0.0 to 5.0 Hz. The assumed dislocation is derived from the Kostrov (1964) displacement function for a continuously propagating stress relaxation. The azimuthal variations in the amplitudes and waveforms directly result from spatially varying slip on the fault, spatially varying radiation pattern over the fault, and the magnitude and direction of the rupture velocity. The near-source ground motions are dominated by the rupture in the direction of the receiver. Using a 100-bar effective stress (initial stress minus sliding friction) in a Poisson solid with β = 3.0 km/sec the shear wave speed, and shear modulus μ = 3.0 × 10^(11) dyne/cm^2, the simulated earthquake has a moment M_o = 4.5 × 10^(25) dyne-cm. Using a rupture velocity of 0.9β, the peak acceleration is 1195 cm/sec^2 and velocity 10^4 cm/sec for the receiver directly on strike. For a receiver 30° off strike, the maximum acceleration 236 cm/sec^2 occurs on the vertical component

Seismicity in a model governed by competing frictional weakening and healing mechanisms

Observations from laboratory, field and numerical work spanning a wide range of space and time scales suggest a strain dependent progressive evolution of material properties that control the stability of earthquake faults. The associated weakening mechanisms are counterbalanced by a variety of restrengthening mechanisms. The efficiency of the healing processes depends on local material properties and on rheologic, temperature, and hydraulic conditions. We investigate the relative effects of these competing non-linear feedbacks on seismogenesis in the context of evolving frictional properties, using a mechanical earthquake model that is governed by slip weakening friction. Weakening and strengthening mechanisms are parametrized by the evolution of the frictional control variable—the slip weakening rate R—using empirical relationships obtained from laboratory experiments. In our model, weakening depends on the slip of an earthquake and tends to increase R, following the behaviour of real and simulated frictional interfaces. Healing causes R to decrease and depends on the time passed since the last slip. Results from models with these competing feedbacks are compared with simulations using non-evolving friction. Compared to fixed R conditions, evolving properties result in a significantly increased variability in the system dynamics. We find that for a given set of weakening parameters the resulting seismicity patterns are sensitive to details of the restrengthening process, such as the healing rate b and a lower cutoff time, tc , up to which no significant change in the friction parameter is observed. For relatively large and small cutoff times, the statistics are typical of fixed large and small R values, respectively. However, a wide range of intermediate values leads to significant fluctuations in the internal energy levels. The frequency-size statistics of earthquake occurrence show corresponding non-stationary characteristics on time scales over which negligible fluctuations are observed in the fixed-R case. The progressive evolution implies that -— except for extreme weakening and healing rates -— faults and fault networks possibly are not well characterized by steady states on typical catalogue time scales, thus highlighting the essential role of memory and history dependence in seismogenesis. The results suggest that an extrapolation to future seismicity occurrence based on temporally limited data may be misleading due to variability in seismicity patterns associated with competing mechanisms that affect fault stability

Analysis of Site Effects at the Garner Valley Downhole Array Near the San Jacinto Fault

The Garner Valley downhole array is located in the geologically complicated and seismologically active San Jacinto fault zone. The choice of the site and the potential for a large earthquake there are discussed. The equipment is described in detail. The data recorded through the end of 1 April 1990 are summarized. Two large events at different locations are discussed in some detail and analyzed for amplification of the signal at the surface

New Observations and Methods for Modeling Nonlinear Site Response

Refuge accelerogram, 1987 Superstition Hills, CA; and the Kushiro Port station, 1993 Kushiro-Oki, Japan, among others. To understand the nature of these nonlinear effects, we have developed a model of nonlinear soil dynamics that includes nonlinear effects such as anelasticity, hysteretic behavior and cyclic degradation due to pore water pressure. The hysteresis behavior is given by the Generalized Masing rules. This new formulation has a functional representation and it includes the Cundall-Pyke hypothesis and Masing original formulation as special cases. It also provides a mean to quantify anelastic damping as a function of the stress-strain loop. Using the in situ observations from the Gamer Valley downhole seismographic array (GVDSA), we have modeled scenarios of ground motions at the surface for this site. The simulations show amplitude reduction as well as the shift of the fundamental frequency to lower frequencies as observed on vertical arrays. The synthetic accelerograms show the development of intermittent behavior-high frequency peaks riding on low frequency carrier-as observed in the acceleration records mentioned above. Comparisons between the nonlinear model predictions and those computed with the equivalent linear model demonstrate that the latter model fails to capture essential manifestations of nonlinear soil response

Ice nucleation by surrogates for atmospheric mineral dust and mineral dust/sulfate particles at cirrus temperatures

International audienceThis study examines the potential role of some types of mineral dust and mineral dust with sulfuric acid coatings as heterogeneous ice nuclei at cirrus temperatures. Commercially-available nanoscale powder samples of aluminum oxide, alumina-silicate and iron oxide were used as surrogates for atmospheric mineral dust particles, with and without multilayer coverage of sulfuric acid. A sample of Asian dust aerosol particles was also studied. Measurements of ice nucleation were made using a continuous-flow ice-thermal diffusion chamber (CFDC) operated to expose size-selected aerosol particles to temperatures between ?45 and ?60°C and a range of relative humidity above ice-saturated conditions. Pure metal oxide particles supported heterogeneous ice nucleation at lower relative humidities than those required to homogeneously freeze sulfuric acid solution particles at sizes larger than about 50 nm. The ice nucleation behavior of the same metal oxides coated with sulfuric acid indicate heterogeneous freezing at lower relative humidities than those calculated for homogeneous freezing of the diluted particle coatings. The effect of soluble coatings on the ice activation relative humidity varied with the respective uncoated core particle types, but for all types the heterogeneous freezing rates increased with particle size for the same thermodynamic conditions. For a selected size of 200 nm, the natural mineral dust particles were the most effective ice nuclei tested, supporting heterogeneous ice formation at an ice relative humidity of approximately 135%, irrespective of temperature. Modified homogeneous freezing parameterizations and theoretical formulations are shown to have application to the description of heterogeneous freezing of mineral dust-like particles with soluble coatings

Mass spectrometers and atomic oxygen

The likely role of atmospheric atomic oxygen in the recession of spacecraft surfaces and in the shuttle glow has revived interest in the accurate measurement of atomic oxygen densities in the upper atmosphere. The Air Force Geophysics Laboratory is supplying a quadrupole mass spectrometer for a materials interactions flight experiment being planned by the Johnson Space Center. The mass spectrometer will measure the flux of oxygen on test materials and will also identify the products of surface reactions. The instrument will be calibrated at a new facility for producing high energy beams of atomic oxygen at the Los Alamos National Laboratory. The plans for these calibration experiments are summarized

High intensity 5 eV O-atom exposure facility for material degradation studies

An atomic oxygen exposure facility was developed for studies of material degradation. The goal of these studies is to provide design criteria and information for the manufacture of long life (20 to 30 years) construction materials for use in low Earth orbit. The studies that are being undertaken will provide: (1) absolute reaction cross sections for the engineering design problems, (2) formulations of reaction mechanisms for use in the selection of suitable existing materials and the design of new more resistant ones, and (3) the calibration of flight hardware (mass spectrometers, etc.) in order to directly relate experiments performed in low Earth orbit to ground based investigations. The facility consists of a CW laser sustained discharge source of O-atoms, an atomic beam formation and diagnostics system, a spinning rotor viscometer, and provision for using the system for calibration of actual flight instruments