Dynamic Tensile Strength of Lunar Rock Types

The dynamic tensile strengths of four rocks have been determined. A flat plate impact experiment is used to generate ∼1-μs-duration tensile stress pulses in rock samples by superposing rarefaction waves to induce fracture. A gabbroic anorthosite and a basalt were selected because they are the same rock types as occur on the lunar highlands and mare, respectively. Although these have dynamic tensile strengths which lie within the ranges 153–174 MPa and 157–179 –MPa, whereas Arkansas novaculite and Westerly granite exhibit dynamic tensile strengths of 67–88 MPa and 95–116 MPa, respectively, the effect of chemical weathering and other factors, which may affect application of the present results to the moon, have not been explicitly studied. The reported tensile strengths are based on a series of experiments on each rock where determination of incipient spallation is made by terminal microscopic examination. These data are generally consistent with previous determinations, at least one of which was for a significantly chemically altered (hydroxylated) but physically coherent rock. The tensile failure data do not bear a simple relation to compressive results and imply that any modeling involving rock fracture consider the tensile strength of igneous rocks under impulse loads distinct from the values for static tensile strength. Generally, the dynamic tensile strengths of nonporous igneous rocks range from ∼ 100 to 180 MPa, with the more basic, and even amphibole-bearing samples, yielding the higher values

Preearthquake and Postearthquake Creep on the Imperial Fault and the Brawley Fault Zone

Taken together, 12 years of alinement-array data, 4 years of creepmeter records from four instruments, and 2 years of surveys from two nail files suggests that creep events on the Imperial fault 2 to 5 months before the October 15 earthquake are consistent with longterm trends and not indicative of any imminent event. No discernible creep occurred on the fault in the hours and days before the earthquake. Records of coseismic displacement imply that response of the soil to the fault slip at depth was brittle rather than plastic; they uniquely demonstrate that the minimum rate of surface fault displacement was 1.8 cm/s. Continuing measurements of afterslip show that all motion is due to discrete 0.2- to 1.5-cm creep events occurring less frequently over time. The accumulating displacement for the first 35 days after the earthquake is well approximated by linear logarithmic functions of time. Use of this accumulating displacement to predict future slip rates implies that for 6 years the afterslip rate from the 1979 earthquake should be greater than the 0.5-cm/yr average preearthquake creep rate. The maximum amount of slip on the surface trace of the Imperial fault associated with the 1979 earthquake, including afterslip, amounts to more than 60 cm

Fault slip in southern California

Measurements of slip on major faults in southern California have been performed over the past 18 yr using principally theodolite alignment arrays and tautwire extensometers. They provide geodetic control within a few hundred meters of the fault traces, which complements measurements made by other techniques at larger distances. Approximately constant slip rates of from 0.5 to 5 mm/yr over periods of several years have been found for the southwestern portion of the Garlock fault, the Banning and San Andreas faults in the Coachella Valley, the Coyote Creek fault, the Superstition Hills fault, and an unnamed fault 20 km west of El Centro. These slip rates are typically an order of magnitude below displacement rates that have been geodetically measured between points at greater distances from the fault traces. Exponentially decaying postseismic slip in the horizontal and vertical directions due to the 1979 Imperial Valley earthquake has been measured. It is similar in magnitude to the coseismic displacements. Analysis of seismic activity adjacent to slipping faults has shown that accumulated seismic moment is insufficient to explain either the constant or the decaying postseismic slip. Thus the mechanism of motion may differ from that of slipping faults in central California, which move at rates close to the plate motion and are accompanied by sufficient seismic moment. Seismic activity removed from the slipping faults in southern California may be driving their relatively aseismic motion

3D buried utility location using a marching-cross-section algorithm for multi-sensor data fusion

We address the problem of accurately locating buried utility segments by fusing data from multiple sensors using a novel Marching-Cross-Section (MCS) algorithm. Five types of sensors are used in this work: Ground Penetrating Radar (GPR), Passive Magnetic Fields (PMF), Magnetic Gradiometer (MG), Low Frequency Electromagnetic Fields (LFEM) and Vibro-Acoustics (VA). As part of the MCS algorithm, a novel formulation of the extended Kalman Filter (EKF) is proposed for marching existing utility tracks from a scan cross-section (scs) to the next one; novel rules for initializing utilities based on hypothesized detections on the first scs and for associating predicted utility tracks with hypothesized detections in the following scss are introduced. Algorithms are proposed for generating virtual scan lines based on given hypothesized detections when different sensors do not share common scan lines, or when only the coordinates of the hypothesized detections are provided without any information of the actual survey scan lines. The performance of the proposed system is evaluated with both synthetic data and real data. The experimental results in this work demonstrate that the proposed MCS algorithm can locate multiple buried utility segments simultaneously, including both straight and curved utilities, and can separate intersecting segments. By using the probabilities of a hypothesized detection being a pipe or a cable together with its 3D coordinates, the MCS algorithm is able to discriminate a pipe and a cable close to each other. The MCS algorithm can be used for both post-and on-site processing. When it is used on site, the detected tracks on the current scs can help to determine the location and direction of the next scan line. The proposed “multi-utility multi-sensor” system has no limit to the number of buried utilities or the number of sensors, and the more sensor data used, the more buried utility segments can be detected with more accurate location and orientation.</p

Noisy random resistor networks: renormalized field theory for the multifractal moments of the current distribution

We study the multifractal moments of the current distribution in randomly diluted resistor networks near the percolation treshold. When an external current is applied between to terminals $x$ and $x^\prime$ of the network, the $l$th multifractal moment scales as $M_I^{(l)} (x, x^\prime) \sim | x - x^\prime |^{\psi_l /\nu}$, where $\nu$ is the correlation length exponent of the isotropic percolation universality class. By applying our concept of master operators [Europhys. Lett. {\bf 51}, 539 (2000)] we calculate the family of multifractal exponents $\{\psi_l \}$ for $l \geq 0$ to two-loop order. We find that our result is in good agreement with numerical data for three dimensions.Comment: 30 pages, 6 figure

Multifractal properties of resistor diode percolation

Focusing on multifractal properties we investigate electric transport on random resistor diode networks at the phase transition between the non-percolating and the directed percolating phase. Building on first principles such as symmetries and relevance we derive a field theoretic Hamiltonian. Based on this Hamiltonian we determine the multifractal moments of the current distribution that are governed by a family of critical exponents $\{\psi_l \}$. We calculate the family $\{\psi_l \}$ to two-loop order in a diagrammatic perturbation calculation augmented by renormalization group methods.Comment: 21 pages, 5 figures, to appear in Phys. Rev.

Aberrant in Vivo T Helper Type 2 Cell Response and Impaired Eosinophil Recruitment in Cc Chemokine Receptor 8 Knockout Mice

Chemokine receptors transduce signals important for the function and trafficking of leukocytes. Recently, it has been shown that CC chemokine receptor (CCR)8 is selectively expressed by Th2 subsets, but its functional relevance is unclear. To address the biological role of CCR8, we generated CCR8 deficient (−/−) mice. Here we report defective T helper type 2 (Th2) immune responses in vivo in CCR8−/− mice in models of Schistosoma mansoni soluble egg antigen (SEA)-induced granuloma formation as well as ovalbumin (OVA)- and cockroach antigen (CRA)-induced allergic airway inflammation. In these mice, the response to SEA, OVA, and CRA showed impaired Th2 cytokine production that was associated with aberrant type 2 inflammation displaying a 50 to 80% reduction in eosinophils. In contrast, a prototypical Th1 immune response, elicited by Mycobacteria bovis purified protein derivative (PPD) was unaffected by CCR8 deficiency. Mechanistic analyses indicated that Th2 cells developed normally and that the reduction in eosinophil recruitment was likely due to systemic reduction in interleukin 5. These results indicate an important role for CCR8 in Th2 functional responses in vivo

Nuggets, Pearls, and Vignettes of Master Heart Failure Clinicians

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73696/1/j.1527-5299.2001.00307.x.pd

Structure and catalytic regulatory function of ubiquitin specific protease 11 N-terminal and ubiquitin-like domains

The ubiquitin specific protease 11 (USP11) is implicated in DNA repair, viral RNA replication, and TGFβ signaling. We report the first characterization of the USP11 domain architecture and its role in regulating the enzymatic activity. USP11 consists of an N-terminal "domain present in USPs" (DUSP) and "ubiquitin-like" (UBL) domain, together referred to as DU domains, and the catalytic domain harboring a second UBL domain. Crystal structures of the DU domains show a tandem arrangement with a shortened β-hairpin at the two-domain interface and altered surface characteristics compared to the homologues USP4 and USP15. A conserved VEVY motif is a signature feature at the two-domain interface that shapes a potential protein interaction site. Small angle X-ray scattering and gel filtration experiments are consistent with the USP11DU domains and full-length USP11 being monomeric. Unexpectedly, we reveal, through kinetic assays of a series of deletion mutants, that the catalytic activity of USP11 is not regulated through intramolecular autoinhibition or activation by the N-terminal DU or UBL domains. Moreover, ubiquitin chain cleavage assays with all eight linkages reveal a preference for Lys(63)-, Lys(6)-, Lys(33)-, and Lys(11)-linked chains over Lys(27)-, Lys(29)-, and Lys(48)-linked and linear chains consistent with USP11's function in DNA repair pathways that is mediated by the protease domain. Our data support a model whereby USP11 domains outside the catalytic core domain serve as protein interaction or trafficking modules rather than a direct regulatory function of the proteolytic activity. This highlights the diversity of USPs in substrate recognition and regulation of ubiquitin deconjugation