Step-like Change Research Articles

Magneto-optical observations of vortex penetration into Bi2Sr2CaCu2O8+y with periodic pinning potentials

The effect of artificially introduced periodic pinning centers fabricated by focused-ion beam milling is studied in highly anisotropic superconductor Bi2Sr2CaCu2O8+y. Step-like changes of local magnetic induction at integer multiples of the matching field are visualized by magneto-optical imaging. Temperature dependence of the matching phenomenon is understood by considering the saturation number of vortices in each pinning center.

Landslide prediction based on wavelet analysis and cusp catastrophe

During the monitoring engineering of landslides, the monitoring data of accumulated displacement are usually affected by the external factors. Therefore, the displacement curve always has step-like character, which brings some difficulties to the accurate prediction of landslides. In order to solve this problem, based on the wavelet analysis and cusp catastrophe, a new kind of analysis method is proposed in this article. First, Fourier transform method can be used to extract the frequency component of the curve of monitoring displacement. Second, the wavelet transform was adopted to inspect the breakpoints of signals, which can be used to analyze the cause of the occurrence of the step-like character in the curve of landslide monitoring. Based on the cusp catastrophe theory, a nonlinear dynamic model was established to conduct the simulation calculation of time forecasting of landslides. According to a case study of landslide, the periodical rainfall and reservoir level fluctuation are the main factors leading to the step-like changes in the curve of monitoring displacement. In addition, the results of simulation calculation are in agreement with the fact of local failure of landslides. This method can provide a new analysis way for the time prediction of landslides.

Optimal Startup/Shutdown Operating Policies with a Recombinant Strain Continuously Stirred Bioreactor

In this work dynamic optimal startup and shutdown policies were computed and validated in an experimental lab-scale continuous bioreactor. Using the theoretical optimal profile, a reduction in the startup time was achieved when compared to simple steplike changes in the manipulated variables. Therefore, the use of optimal startup policies led to raw material savings. To test the optimal startup policies, two operating points were selected. Experiments were run at these conditions to fit kinetic rate constants leading to a reliable model representation of the addressed biosystem. The practical implementation of theoretical optimization results is not a trivial task, and this is a major contribution of the present work. This is true especially for the optimal dynamic shutdown results that are not, up to our best knowledge, reported in the open literature.

Magnetic and structural anomalies of NanC60 (n = 2, 3)

Abstract Sodium fullerides NanC60 (n = 2, 3) have been synthesized by a liquid phase reaction and investigated with X-ray diffraction (XRD), nuclear magnetic resonance (NMR), electron paramagnetic resonance, and differential thermal analysis. XRD data indicate that the crystal structure of Na2C60 at 300 K is face centered cubic (FCC). A phase transition from primitive cubic to FCC crystal structure has been observed in this work in Na2C60 fulleride at 290 K. The transition is accompanied by the step-like change of paramagnetic susceptibility. The crystal structure of Na3C60 is more complicated than, and different from, what has been reported in the literature. A nearly seven-fold increase of paramagnetic susceptibility with increasing temperature has been observed in the Na3C60 fulleride at 240–260 K. In the same temperature range, a new line at about 255 ppm appears in the 23Na NMR spectrum, indicating a significant increase of electron density near the Na nucleus. The observed effect can be explained by a metal-insulator transition caused by a structural transition.

Seven modes of healthcare operations - a tool for casemix analysis?

Seven modes of healthcare operations - a tool for casemix analysis?

Inhibition of beta 1–40 amyloid fibrillation with N-acetyl- l-cysteine capped quantum dots

One of the primary factors that induce Alzheimer's disease (AD) is the deposition of beta-amyloid (A β). The A β molecules can self-assemble to form neurotoxic aggregates with various morphologies, such as dimers, oligomers, protofibrils and fibrils. For this aspect, we demonstrated that the amyloid fibrillation can be inhibited by quenching the nucleation and elongation processes with a low concentration of water dispersed N-acetyl- l-cysteine capped quantum dots (NAC-QDs). Based on the concentration dependence of NAC-QDs on the seeded fibril growth, there is a remarkable inhibition effect when the NAC-QDs concentration is increased by 100-fold from 10 −9 to 10 −7 m. The NAC-QDs concentration required to show inhibition effect is much lower than that of the amyloid peptide concentration (50 μ m). The step-like change suggests that the inhibition effect of NAC-QDs displays a threshold response. The inhibition is likely due to the intermolecular attractive interactions such as the hydrogen bonding between NAC-QDs and amyloid fibrils resulting in the blockage of the active elongation sites on the fibrils.

Vector singularities of the combined beams assembled from mutually incoherent orthogonally polarized components

It is shown that, for an incoherent superposition of the orthogonally polarized laser beams, the vector singularities of a specific type arise at the transversal cross section of a paraxial combined beam instead of common singularities, such as amplitude zeros or optical vortices (inherent in scalar, i.e. homogeneously polarized, fields), and C points, where polarization is circular, and L lines, along which polarization is linear (inherent in completely coherent vector, i.e. inhomogeneously polarized fields). There are U lines (closed or closing at infinity) along which the degree of polarization equals zero and the state of polarization is undetermined, and isolated P points where the degree of polarization equals unity and the state of polarization is determined by the non-vanishing component of the combined beam. U surfaces and P lines correspond to such singularities in three dimensions, by analogy with L surfaces and C lines in three-dimensional completely coherent vector fields. P lines directly reflect the snake-like distortions of a wavefront of the singular component of the combined beam. Crossing of the U line (surface) is accompanied by a step-like change of the state of polarization onto the orthogonal one. U and P singularities are adequately described in terms of the complex degree of polarization with the representation at the Stokes space, namely at and inside of the Poincare sphere. The conditions of topological stability of U and P singularities are discussed, as well as the peculiarities of the spatial distribution of the degree of polarization in the closest vicinity to such singularities. Experimental examples of reconstruction of the combined beam's vector skeleton formed by U and P singularities as the extrema of the complex degree of polarization are given. Comparison with the related investigations is provided.

Surface Displacement and Groundwater Level Changes Associated with the 24 May 2006 Mw 5.4 Morelia Fault Earthquake, Mexicali Valley, Baja California, Mexico

On 24 May 2006, a moderate-size ( M w 5.4) earthquake occurred in the Mexicali Valley, Mexico. The event created 5 km of surface rupture. Associated deformation was recorded by geotechnical instruments, leveling profile, and synthetic aperture radar interferometry. A coseismic steplike groundwater level change was detected at seven wells. The surface rupture consisted of up to 30 cm of primarily normal displacement. 20–25 cm of vertical offset was recorded by a crackmeter and 20 cm on leveling line. We created Envisat C-band interferograms spanning the 24 May 2006 earthquake to image the coseismic displacement. Although the coherence of the interferometric images is low, the images clearly show a spatial displacement field centered on the known surface rupture that is consistent with the expected sense of motion. The interferograms and leveling line also include subsidence related to geothermal production. This anthropogenic subsidence component was estimated using a pre-event interferogram. Source parameters for the earthquake were estimated using forward modeling of both surface deformation data and static volume strain change (inferred from coseismic changes in groundwater level). Modeling was based on finite rectangular fault embedded in an elastic media. The preferred fault model has a strike, rake, and dip of (48°, -89°, 45°) and has a length of 5.2 km, width of 6.7 km, and 34 cm of uniform slip. The geodetic moment, based on the modeled fault parameters, is ![Graphic][1] . The model matched the observed surface deformation, expected groundwater changes, and teleseismic moment reasonably well. [1]: /embed/inline-graphic-1.gif

The effect of Ag substitution in the mixed conductor Cu 7PSe 6

Cu 7PSe 6 is a mixed conductor that crystallizes in the simple cubic structure at room temperature. Structural transitions above and below room temperature are accompanied by step-like changes in electrical conductivity. The substitution of Ag + for Cu + in Cu 7PSe 6 stabilized the simple cubic structure over a wider range of temperatures than is observed for the pure compound. A disproportionate decrease in electrical conductivity accompanies modest levels of silver substitution. The prominent step in electrical conductivity associated with the low-temperature crystallographic phase transition disappears in (Ag x Cu 1− x ) 7PSe 6 solid solutions for a composition parameter x=0.20, replaced by two distinct changes in the slope of conductivity below room temperature.

A Detailed Comparison of Experimental and Numerical Data on Hydraulic Fracture Height Growth Through Stress Contrasts

Summary This paper compares height, length, width, and pressure data from a laboratory experiment to predictions from a three-dimensional (3D) planar hydraulic fracture model for the case of a fracture propagating in a lower-stress payzone region bounded by two symmetric higher-stress barrier regions. A laboratory method that creates step-like stress changes on an interface between two transparent polymethylmethacrylate (PMMA) blocks is described. A fracture is propagated along this interface while measuring fracture geometry and full-field fracture width (opening) by analysis of the light intensity in images of the growing fracture. The fracture grew in overall height to 1.7 times the pay height and in half-length to 3 times the pay height. Results from a planar 3D numerical model closely matched the experimental data for overall fracture shape, length, height growth, and injection pressure. The data are presented so other numerical models can be compared with these detailed measurements.

Evolution of self-organized bulk vortex structure induced by hole doping in the high-temperature superconductorYBa2Cu3O7−δ

Studies of the persistent current relaxation of ${\text{YBa}}_{2}{\text{Cu}}_{3}{\text{O}}_{7\ensuremath{-}\ensuremath{\delta}}$ ring-shaped thin films as a function of oxygen concentration (with 24 increments in $\ensuremath{\delta}$ every $\ensuremath{\sim}0.021$, over a range between 0.03 and 0.55) allowed us to construct the $(\ensuremath{\mu},\ensuremath{\delta})$ phase diagram where the exponent $\ensuremath{\mu}$ characterizes the pinning ability and the nature of the vortex structure. The reduction of the hole-doping level (an increase in $\ensuremath{\delta}$) transforms the vortex structure from quasi-lattice into a glass and subsequently into a pinned liquid phase. These vortex phases self-organize and produce relaxation plateaus in regions between steplike changes in the dependence of relaxation kinetics on hole doping.

Formation and structure of a soliton in an antiferroelectric liquid crystal in an electric field

The soliton structure in an antiferroelectric liquid crystal in an electric field is calculated in the discrete phenomenological Landau model for phase transitions. The anticlinic structure of the antiferroelectric crystal gives rise to nontrivial features of the soliton structure and the stability of the soliton. The soliton is topologically stable in a metastable state if the electric field is much higher than the field of antiferroelectric-helix unwinding. A structural transition with a step-like change in the orientation of molecules occurs as the soliton field varies. A peculiar soliton (synclinic pair) can be formed if the barrier between the anti- and ferroelectric structures is large. The calculation shows the possibility of a large electroclinic effect in the soliton, i.e., a variation in the molecular tilt angle in an electric field in the vicinity of the transition of the structure to the synclinic state.

Climate controls on marine ecosystems and fish populations

This paper discusses large-scale climate variability for several marine ecosystems and suggests types of ecosystem responses to climate change. Our analysis of observations and model results for the Pacific and Atlantic Oceans concludes that most climate variability is accounted for by the combination of intermittent 1–2 year duration events, e.g. the cumulative effect of monthly weather anomalies or the more organized El Niño/La Niña, plus broad-band “red noise” intrinsic variability operating at decadal and longer timescales. While ocean processes such as heat storage and lags due to ocean circulation provide some multi-year memory to the climate system, basic understanding of the mechanisms resulting in observed large decadal variability is lacking and forces the adoption of a “stochastic or red noise” conceptual model of low frequency variability at the present time. Thus we conclude that decadal events with rapid shifts and major departures from climatic means will occur, but their timing cannot be forecast. The responses to climate by biological systems are diverse in character because intervening processes introduce a variety of amplifications, time lags, feedbacks, and non-linearities. Decadal ecosystem variability can involve a variety of climate to ecosystem transfer functions. These can be expected to convert red noise of the physical system to redder (lower frequency) noise of the biological response, but can also convert climatic red noise to more abrupt and discontinuous biological shifts, transient climatic disturbance to prolonged ecosystem recovery, and perhaps transient disturbance to sustained ecosystem regimes. All of these ecosystem response characteristics are likely to be active for at least some locations and time periods, leading to a mix of slow fluctuations, prolonged trends, and step-like changes in ecosystems and fish populations in response to climate change. Climate variables such as temperatures and winds can have strong teleconnections (large spatial covariability) within individual ocean basins, but between-basin teleconnections, and potential climate-driven biological synchrony over several decades, are usually much weaker and a highly intermittent function of the conditions prevailing at the time within the adjoining basins. As noted in the recent IPCC 4th Assessment Report, a warming trend of ocean surface layers and loss of regional sea ice is likely before 2030, due to addition of greenhouse gases. Combined with large continuing natural climate variability, this will stress ecosystems in ways that they have not encountered for at least 100s of years.

Groundwater changes associated with the 2004 Niigata-Chuetsu and 2007 Chuetsu-oki earthquakes

AbstractThe Geological Survey of Japan, AIST, has been monitoring groundwater in and around the Kinki and Tokai districts for earthquake prediction research. The Niigata Prefectural Office has also been observing groundwater for monitoring land subsidence in Niigata Prefecture. The 2004 Niigata-Chuetsu (MJMA6.8) and 2007 Chuetsuoki (MJMA6.8) earthquakes occurred in Niigata Prefecture, Japan, on October 23, 2004 and July 16, 2007, respectively. The two earthquakes have a similar magnitude, epicenter, and mechanism. At many of the observation wells, we detected changes in groundwater level or pressure related to the two earthquakes, but no clear precursory changes. At all of our observation wells in Niigata Prefecture, trend changes were observed after coseismic step-like changes for both of the earthquakes. At some of the stations in and around the Kinki and Tokai districts, coseismic trend changes and/or step-like changes were observed. The pattern of the changes were almost similar for the two earthquakes. Those changes were considered to be caused not by the static crustal deformation but by the ground shaking.

Groundwater level changes related to the ground shaking of the Noto Hanto Earthquake in 2007

AbstractThe Geological Survey of Japan, AIST has been monitoring groundwater using the observation network of about 40 stations in and around the Kinki and Tokai districts for earthquake prediction research. The Noto Hanto Earthquake in 2007 (MJMA6.9) occurred in the northwestern part of the Noto Hanto Peninsula, Japan on March 25, 2007. The epicentral distance to the nearest and furthest observation well is about 100 km and 400 km, respectively. Changes in groundwater level related to the Noto Hanto Earthquake were detected at many stations. Most of these were changes in the long-term trend and/or short-term oscillation; there were a few steplike changes. The coseismic static volumetric strain changes calculated from the fault model ranged between 10−9and 10−10at most of the observation stations. These changes were therefore considered to be groundwater changes caused by the ground shaking because groundwater level sensitivity to crustal volumetric strain is a few centimeters to 10−8strain at the most. We compared the coseismic groundwater level changes for the Noto Hanto Earthquake with those for five recent large earthquakes and obtained rough characteristics of the effect of the ground shaking on the groundwater level at each of the observation stations.

Charge detection in graphene quantum dots

We report measurements on a graphene quantum dot with an integrated graphene charge detector. The quantum dot device consists of a graphene island (diameter of ∼200 nm) connected to source and drain contacts via two narrow graphene constrictions. From Coulomb diamond measurements a charging energy of 4.3 meV is extracted. The charge detector is based on a 45 nm wide graphene nanoribbon placed approximately 60 nm from the island. We show that resonances in the nanoribbon can be used to detect individual charging events on the quantum dot. The charging induced potential change on the quantum dot causes a steplike change in the current in the charge detector. The relative change in the current ranges from 10% up to 60% for detecting individual charging events.

Transient Changes in Well-Water Level in Bore Wells in Western India Due to the 2004 Mw 9.3 Sumatra Earthquake

Large water level changes were observed in six bore wells in the Koyna region in western India following the Great Sumatra earthquake of M w 9.3 on 2004 December 26. This earthquake occurred at 00:58:50 coordinated universal time (UTC) off the coast of Sumatra located about 3000 km from the Koyna region. The arrival time of the P wave recorded at the Koyna seismic station was 01:04:24.45 (UTC). The anomalous water level changes were observed at 01:15 (UTC) at all of these wells where the sampling rate was 15 min. No abnormal changes were noticed in the preceding sampling time at 01:00 (UTC), clearly indicating that these changes occurred due to the passage of seismic waves generated by the Sumatra earthquake. However, due to the large sampling interval, it is difficult to correlate the water level changes either to shear or surface waves. No local earthquake was recorded by the network during this period. The anomalous water level changes were of the order of 2–65 cm and show either a spikelike or a steplike change. These types of changes are attributed to the dynamic strain induced by the passage of seismic waves, most probably long-period surface waves.

Joint Variability of Global Runoff and Global Sea Surface Temperatures

Abstract Global land surface runoff and sea surface temperatures (SST) are analyzed to identify the primary modes of variability of these hydroclimatic data for the period 1905–2002. A monthly water-balance model first is used with global monthly temperature and precipitation data to compute time series of annual gridded runoff for the analysis period. The annual runoff time series data are combined with gridded annual sea surface temperature data, and the combined dataset is subjected to a principal components analysis (PCA) to identify the primary modes of variability. The first three components from the PCA explain 29% of the total variability in the combined runoff/SST dataset. The first component explains 15% of the total variance and primarily represents long-term trends in the data. The long-term trends in SSTs are evident as warming in all of the oceans. The associated long-term trends in runoff suggest increasing flows for parts of North America, South America, Eurasia, and Australia; decreasing runoff is most notable in western Africa. The second principal component explains 9% of the total variance and reflects variability of the El Niño–Southern Oscillation (ENSO) and its associated influence on global annual runoff patterns. The third component explains 5% of the total variance and indicates a response of global annual runoff to variability in North Atlantic SSTs. The association between runoff and North Atlantic SSTs may explain an apparent steplike change in runoff that occurred around 1970 for a number of continental regions.

Combined thermodynamic and rare earth element modelling of garnet growth during subduction: Examples from ultrahigh-pressure eclogite of the Western Gneiss Region, Norway

Major and trace element zonation patterns were determined in ultrahigh-pressure eclogite garnets from the Western Gneiss Region (Norway). All investigated garnets show multiple growth zones and preserve complex growth zonation patterns with respect to both major and rare earth elements (REE). Due to chemical differences of the host rocks two types of major element compositional zonation patterns occur: (1) abrupt, step-like compositional changes corresponding with the growth zones and (2) compositionally homogeneous interiors, independent of growth zones, followed by abrupt chemical changes towards the rims. Despite differences in major element zonation, the REE patterns are almost identical in all garnets and can be divided into four distinct zones with characteristic patterns. In order to interpret the major and trace element distribution and zoning patterns in terms of the subduction history of the rocks, we combined thermodynamic forward models for appropriate bulk rock compositions to yield molar proportions and major element compositions of stable phases along the inferred pressure-temperature path with a mass balance distribution of REEs among the calculated stable phases during high pressure metamorphism. Our thermodynamic forward models reproduce the complex major element zonation patterns and growth zones in the natural garnets, with garnet growth predicted during four different reaction stages: (1) chlorite breakdown, (2) epidote breakdown, (3) amphibole breakdown and (4) reduction in molar clinopyroxene at ultrahigh-pressure conditions. Mass-balance of the rare earth element distribution among the modelled stable phases yielded characteristic zonation patterns in garnet that closely resemble those in the natural samples. Garnet growth and trace element incorporation occurred in near thermodynamic equilibrium with matrix phases during subduction. The rare earth element patterns in garnet exhibit distinct enrichment zones that fingerprint the minerals involved in the garnet-forming reactions as well as local peaks that can be explained by fractionation effects and changes in the mineral assemblage.

Study of hysteresis for steplike giant magnetoimpedance sensor based on magnetic energy

A giant magnetoimpedance sensor with a steplike impedance property was reported in the case of amorphous soft magnetic thin film in a rectangle shape with an in-plane uniaxial easy axis in a controlled direction. The steplike change of impedance happens simultaneously with a change of magnetic domain, and its physical basis was declared as the intersection of the level of magnetic energy in each case of these domain structures. An actual variation of steplike impedance as a function of external magnetic field typically has a hysteretic property. In this study, an explanation of the hysteretic property is discussed based on an introduction of asymmetrical threshold energy, and then an experimental confirmation is carried out for the proposed analytical model.