471 research outputs found
Landslides in sensitive soils, Tauranga, New Zealand.
In the Tauranga region sensitive soil failures commonly occur after heavy rainfall events, causing considerable infrastructure damage. Several notable landslides include a large failure at Bramley Drive, Omokoroa in 1979, the Ruahihi Canal collapse in 1981, and numerous landslides in May 2005; recently the Bramley Drive scarp was reactivated in 2011. These failures are associated with materials loosely classified as the Pahoia Tephras - a mixture of rhyolitic pyroclastic deposits of approximately 1 Ma.
The common link with extreme rainfall events suggests a pore water pressure control on the initiation of these failures. Recent research on the structure of the soils shows a dominance of halloysite clay minerals packed loosely in arrangements with high porosity (51 – 77 %), but with almost entirely micropores. This leads us to conclude that the permeability is very low, and the materials remain continuously wet. The formation of halloysite is encouraged by a wet environment with no episodes of drying, supporting this assumption.
A high-resolution CPT trace at Bramley Drive indicates induced pore water pressures rising steadily to a peak at approximately 25 m depth; this depth coincides with the base of the landslide scarp. We infer that elevated pore water pressures develop within this single, thick aquifer, triggering failure through reduced effective stresses. The inactive halloysite clay mineral results in low plasticity indices (13 – 44 %) and hence high liquidity indices (1.2 – 2.4) due to the saturated pore space; remoulding following failure is sudden and dramatic and results in large debris runout distances
On the Evolution Equation for Magnetic Geodesics
In this paper we prove the existence of long time solutions for the parabolic
equation for closed magnetic geodesics.Comment: In this paper we prove the existence of long time solutions for the
parabolic equation for closed magnetic geodesic
Activation of neutrophils within pulmonary microvessels of rabbits exposed to cigarette smoke.
Previous studies have shown that polymorphonuclear leukocytes (PMN) are delayed in the pulmonary capillaries by the presence of cigarette smoke. To determine if the PMN delayed by smoking are activated, we estimated the in vivo expression of CD11/CD18 and L-selectin on the surface of PMN in lungs and peripheral blood of rabbits because these molecules are known to be upregulated and downregulated, respectively, on the surface of activated PMN. New Zealand white rabbits (3.5 +/- 0.1 kg) were exposed to either air (n = 5) or cigarette smoke (n = 5), and we used an established protocol to measure pulmonary vascular blood flow, volume, and red blood cell (RBC) transit time in the left lung. The right lungs were then fixed in 0.025% glutaraldehyde and stored in liquid nitrogen. Ultrathin sections were immuno-labeled with either the anti-CD18 monoclonal antibody 60.3 or the anti-L-selectin antibody Dreg-200, followed by a secondary antibody conjugated to 10 nm colloidal gold. The target antigens were quantified by counting the number of gold particles per micron (G/microns) of PMN surface membrane. The data show that smoke exposure had no effect on pulmonary blood flow, volume, or RBC transit time. However, it increased the expression of CD11/CD18 on intravascular PMN in the upper region of the lung (control, 7.4 +/- 1.3 G/microns; smoke-exposed, 13.2 +/- 3.3 G/microns; P < 0.05) and decreased the expression of L-selectin on intravascular PMN in both the lower (control, 5.5 +/- 2.0 G/microns; smoke-exposed, 2.6 +/- 1.5 G/microns; P = 0.05) and the upper (control, 6.8 +/- 1.4 G/microns; smoke-exposed, 2.6 +/- 1.2 G/microns; P < 0.05) regions
Chemostratigraphy of Neoproterozoic carbonates: implications for 'blind dating'
The delta C-13(carb) and Sr-87/Sr-86 secular variations in Neoproteozoic seawater have been used for the purpose of 'isotope stratigraphy' but there are a number of problems that can preclude its routine use. In particular, it cannot be used with confidence for 'blind dating'. The compilation of isotopic data on carbonate rocks reveals a high level of inconsistency between various carbon isotope age curves constructed for Neoproteozoic seawater, caused by a relatively high frequency of both global and local delta C-13(carb) fluctuations combined with few reliable age determinations. Further complication is caused by the unresolved problem as to whether two or four glaciations, and associated negative delta C-13(carb) excursions, can be reliably documented. Carbon isotope stratigraphy cannot be used alone for geological correlation and 'blind dating'. Strontium isotope stratigraphy is a more reliable and precise tool for stratigraphic correlations and indirect age determinations. Combining strontium and carbon isotope stratigraphy, several discrete ages within the 590-544 Myr interval, and two age-groups at 660-610 and 740-690 Myr can be resolved
A model independent spin analysis of fundamental particles using azimuthal asymmetries
Exploiting the azimuthal angle dependence of the density matrices we
construct observables that directly measure the spin of a heavy unstable
particle. A novelty of the approach is that the analysis of the azimuthal angle
dependence in a frame other than the usual helicity frame offers an independent
cross-check on the extraction of the spin. Moreover, in some instances when the
transverse polarisation tensor of highest rank is vanishing, for an accidental
or dynamical reason, the standard azimuthal asymmetries vanish and would lead
to a measurement with a wrong spin assignment. In a frame such as the one we
construct, the correct spin assignment would however still be possible. The
method gives direct information about the spin of the particle under
consideration and the same event sample can be used to identify the spins of
each particle in a decay chain. A drawback of the method is that it is
instrumental only when the momenta of the test particle can be reconstructed.
However we hope that it might still be of use in situations with only partial
reconstruction. We also derive the conditions on the production and decay
mechanisms for the spins, and hence the polarisations, to be measured at a
collider experiment. As an example for the use of the method we consider the
simultaneous reconstruction, at the partonic level, of the spin of both the top
and the in top pair production in in the semi-leptonic channel.Comment: 42 pages, 7 figures, 4 table
The Kuiper Belt and Other Debris Disks
We discuss the current knowledge of the Solar system, focusing on bodies in
the outer regions, on the information they provide concerning Solar system
formation, and on the possible relationships that may exist between our system
and the debris disks of other stars. Beyond the domains of the Terrestrial and
giant planets, the comets in the Kuiper belt and the Oort cloud preserve some
of our most pristine materials. The Kuiper belt, in particular, is a
collisional dust source and a scientific bridge to the dusty "debris disks"
observed around many nearby main-sequence stars. Study of the Solar system
provides a level of detail that we cannot discern in the distant disks while
observations of the disks may help to set the Solar system in proper context.Comment: 50 pages, 25 Figures. To appear in conference proceedings book
"Astrophysics in the Next Decade
The flyby anomaly: a multivariate analysis approach
[EN] The flyby anomaly is the unexpected variation of the asymptotic post-encounter velocity of a spacecraft with respect to the pre-encounter velocity as it performs a slingshot manoeuvre. This effect has been detected in, at least, six flybys of the Earth but it has not appeared in other recent flybys. In order to find a pattern in these, apparently contradictory, data several phenomenological formulas have been proposed but all have failed to predict a new result in agreement with the observations. In this paper we use a multivariate dimensional analysis approach to propose a fitting of the data in terms of the local parameters at perigee, as it would occur if this anomaly comes from an unknown fifth force with latitude dependence. Under this assumption, we estimate the range of this force around 300 km .Acedo Rodríguez, L. (2017). The flyby anomaly: a multivariate analysis approach. Astrophysics and Space Science. 362(2):1-7. doi:10.1007/s10509-017-3025-zS173622Acedo, L.: Adv. 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Organizational and Leadership Implications for Transformational Development
Transformational development is a concept of change that originated in the Christian context but has now become generally used in the work of both secular and faith-based organizations. The growing use of the concept by organizations that are fundamentally different has naturally led to some confusion about what the concept means and what it takes to effectively implement it. In this article, we describe the key features of the concept and how they are important in determining the organizational requirements for its effective implementation. Drawing on a few cases, the paper highlights the centrality of faith in transformational development work
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