Well-defined Regimes Research Articles

Exchange Rate Regimes in the Modern Era: Fixed, Floating, and Flaky

This paper provides a selective survey of the incidence, causes, and consequences of a country's choice of its exchange rate regime. I begin with a critical review of Michael Klein and Jay C. Shambaugh's (2010) book Exchange Rate Regimes in the Modern Era, and then proceed to provide an alternative overview of what the economics profession knows and needs to know about exchange rate regimes. While a fixed exchange rate with capital mobility is a well-defined monetary regime, floating is not; thus, it is unclear whether it is theoretically sensible to compare countries across exchange rate regimes. This comparison is quite difficult to make empirically. It is often hard to figure out what the exchange rate regime of a country is in practice, since there are multiple conflicting regime classifications. More importantly, similar countries choose radically different exchange rate regimes without substantive consequences for macroeconomic outcomes like output growth and inflation. That is, the profession knows surprisingly little about either the causes or consequences of national choices of exchange rate regimes. But since the consequences of these choices are small, understanding their causes is of only academic interest. (JEL E52, F33)

Molecular Dynamics of Amorphous Gentiobiose Studied by Solid-State NMR

A solid-state NMR (SSNMR) study is reported on the effect of temperature on the molecular mobility of amorphous gentiobiose, which is complemented with data obtained from crystalline samples. (13)C cross-polarization/magic-angle-spinning (CPMAS) spectra and (1)H MAS spectra were obtained for gentiobiose at natural abundance, in the amorphous state, from 293 K up to the glass transformation region (T(g) = 359 K). Two well-defined molecular mobility regimes were observed, corresponding to different motional modes. NMR results on molecular dynamics are discussed and compared with those obtained by thermally stimulated depolarization currents (TSDC) and dielectric relaxation spectroscopy (DRS). SSNMR spectra presented evidence for a new polymorphic form of gentiobiose, not yet reported in the literature, which is obtained by slow heating of the amorphous solid up to 364 K inside the NMR zirconia rotor.

Laser printing of polythiophene for organic electronics

We report on the development of hybrid organic/inorganic thin-film transistors using regioregular poly-3-hexylthiophene (P3HT) semiconductor material deposited by means of the solid-phase Laser Induced Forward Transfer (LIFT) technique. P3HT pixels were LIFT-printed onto Au/Ti source and drain electrodes formed on silicon dioxide/p +-type Si substrate. Deposition of the P3HT pixels was investigated as a function of the laser fluence using donor substrates with and without a dynamic release layer. Device electrical characterization reveals efficient field-effect action of the bottom gate on the organic channel. The transfer I DS– V GS characteristics exhibit well-defined sub-threshold, linear and saturation regimes designating LIFT as a promising technique for hybrid organic/inorganic transistor technology.

The oxygen evolution methodology affects photosynthetic rate measurements of microalgae in well‐defined light regimes

Designing photobioreactors correctly is a must for the success of microalgal mass production. Optimal photobioreactor design requires a precise knowledge of photosynthesis dynamics in fluctuating light conditions and hence a method for the measurement of photosynthetic rates in specific light regimes. However, it is not uncommon in literature that experimental protocols used to obtain oxygen generation rates are described ambiguously and the reported rates of photosynthesis vary widely depending on the methodology. Additionally, quite a number of methods overlook certain aspects that can affect the estimated rates significantly, and can therefore affect photobioreactor design. We have developed a method based on oxygen evolution measurements that accurately determines photosynthetic rates under well-defined light regimes. Our experimental protocol takes into account most of the issues that can affect the rates of oxygen generation, such as depletion of nutrients during the measurements and precision of the measurements. We have focused on the basic applications in photobioreactor design and used a dynamic model of photosynthesis to analyze our results and compare them with available published data. The results suggest that our oxygen evolution method is consistent.

Pulsed-laser printing of organic thin-film transistors

Organic thin-film transistors have been fabricated using laser-induced forward transfer as spatially resolved laser-printing method. Using this technique, source and drain electrodes were deposited from silver nanoparticle ink and the copper phthalocyanine (CuPc) was used to form the active layer. Both kinds of materials were transferred from a donor substrate onto a receiver substrate upon irradiation with laser pulses in the picosecond regime. The latter substrate formed the gate and the dielectric of the transistor. Electrical characterizations showed that the transistors are fully operative, showing well-defined linear and saturation regimes in the I-V curves.

Concentration dependence of the Er3+ visible and infrared luminescence in Y2−xErxO3 thin films on Si

Y 2 − x Er x O 3 thin films, with x varying between 0 and 0.72, have been successfully grown on crystalline silicon (c-Si) substrates by radio-frequency magnetron cosputtering of Y2O3 and Er2O3 targets. As-deposited films are polycrystalline, showing the body-centered cubic structure of Y2O3, and show only a slight lattice parameter contraction when x is increased, owing to the insertion of Er ions. All the films exhibit intense Er-related optical emission at room temperature both in the visible and infrared regions. By studying the optical properties for different excitation conditions and for different Er contents, all the mechanisms (i.e., cross relaxations, up-conversions, and energy transfers to impurities) responsible for the photoluminescence (PL) emission have been identified, and the existence of two different well-defined Er concentration regimes has been demonstrated. In the low concentration regime (x up to 0.05, Er-doped regime), the visible PL emission reaches its highest intensity, owing to the influence of up-conversions, thus giving the possibility of using Y2−xErxO3 films as an up-converting layer in the rear of silicon solar cells. However, most of the excited Er ions populate the first two excited levels I411/2 and I413/2, and above a certain excitation flux a population inversion condition between the former and the latter is achieved, opening the route for the realization of amplifiers at 2.75 μm. Instead, in the high concentration regime (Er-compound regime), an increase in the nonradiative decay rates is observed, owing to the occurrence of cross relaxations or energy transfers to impurities. As a consequence, the PL emission at 1.54 μm becomes the most intense, thus determining possible applications for Y2−xErxO3 as an infrared emitting material.

Dissection of Symbiosis and Organ Development by Integrated Transcriptome Analysis of Lotus japonicus Mutant and Wild-Type Plants

Genetic analyses of plant symbiotic mutants has led to the identification of key genes involved in Rhizobium-legume communication as well as in development and function of nitrogen fixing root nodules. However, the impact of these genes in coordinating the transcriptional programs of nodule development has only been studied in limited and isolated studies. Here, we present an integrated genome-wide analysis of transcriptome landscapes in Lotus japonicus wild-type and symbiotic mutant plants. Encompassing five different organs, five stages of the sequentially developed determinate Lotus root nodules, and eight mutants impaired at different stages of the symbiotic interaction, our data set integrates an unprecedented combination of organ- or tissue-specific profiles with mutant transcript profiles. In total, 38 different conditions sampled under the same well-defined growth regimes were included. This comprehensive analysis unravelled new and unexpected patterns of transcriptional regulation during symbiosis and organ development. Contrary to expectations, none of the previously characterized nodulins were among the 37 genes specifically expressed in nodules. Another surprise was the extensive transcriptional response in whole root compared to the susceptible root zone where the cellular response is most pronounced. A large number of transcripts predicted to encode transcriptional regulators, receptors and proteins involved in signal transduction, as well as many genes with unknown function, were found to be regulated during nodule organogenesis and rhizobial infection. Combining wild type and mutant profiles of these transcripts demonstrates the activation of a complex genetic program that delineates symbiotic nitrogen fixation. The complete data set was organized into an indexed expression directory that is accessible from a resource database, and here we present selected examples of biological questions that can be addressed with this comprehensive and powerful gene expression data set.

Synopsis of supervised and unsupervised pattern classification techniques applied to volcanic tremor data at Mt Etna, Italy

SUMMARY States of volcanic activity at Mt Etna develop in well-defined regimes with variable duration from a few hours to several months. Changes in the regimes are usually concurrent with variations of the characteristics of volcanic tremor, which is continuously recorded as background seismic radiation. This strict relationship is useful for monitoring volcanic activity in any moment and in whatever condition. We investigated the development of tremor features and its relation to regimes of volcanic activity applying pattern classification techniques. We present results from supervised and unsupervised classification methods applied to 425 patterns of volcanic tremor recorded between 2001 July and August, when a volcano unrest occurred. Support Vector Machine (SVM) and multilayer perceptron (MLP) were used as pattern classifiers with supervised learning. For the SVM and MLP training, we considered four target classes, that is, pre-eruptive, lava fountains, eruptive and post-eruptive. Using a leave one out testing scheme, SVM reached a score of 94.8 per cent of patterns matching the actual class membership, whereas MLP achieved 81.9 per cent of matching patterns. The excellent results, in particular those obtained with SVM, confirmed the reproducibility of the a priori classification. Unsupervised classification was carried out using cluster analysis (CA) and self-organizing maps (SOM). The clusters identified in unsupervised classification formed well-defined regimes, which can be easily related to the four a priori classes aforementioned. Besides, CA found a further cluster concurrent with the climax of eruptive activity. Applying a proper colour-coding to the microclusters (the so-called best matching units) identified by SOM, it was visually possible to follow the development of the characteristics of the tremor data with time, highlighting transitional stages from a regime of volcanic activity to another one. We conclude that supervised and unsupervised classification methods can be conveniently implemented as complementary tools for an in-depth understanding of the relationships between tremor data and volcanic phenomena.

Local and nonlocal dispersive turbulence

We consider the evolution of a family of two-dimensional (2D) dispersive turbulence models. The members of this family involve the nonlinear advection of a dynamically active scalar field, and as per convention, the locality of the streamfunction-scalar relation is denoted by α, with smaller α implying increased locality (α=1 gives traditional 2D dynamics). The dispersive nature arises via a linear term whose strength, after nondimensionalization, is characterized by a parameter ϵ. Setting 0<ϵ≤1, we investigate the interplay of advection and dispersion for differing degrees of locality. Specifically, we study the forward (inverse) transfer of enstrophy (energy) under large-scale (small-scale) random forcing along with the geometry of the scalar field. Straightforward arguments suggest that for small α the scalar field should consist of progressively larger isotropic eddies, while for large α the scalar field is expected to have a filamentary structure resulting from a stretch and fold mechanism, much like that of a small-scale passive field when advected by a large-scale smooth flow. Confirming this, we proceed to forced/dissipative dispersive numerical experiments under weakly nonlocal to local conditions (i.e., α≤1). In all cases we see the establishment of well-defined spectral scaling regimes. For ϵ∼1, there is quantitative agreement between nondispersive estimates and observed slopes in the inverse energy transfer regime. On the other hand, forward enstrophy transfer regime always yields slopes that are significantly steeper than the corresponding nondispersive estimate. At present resolution, additional simulations show the scaling in the inverse regime to be sensitive to the strength of the dispersive term: specifically, as ϵ decreases, quite expectedly the inertial-range shortens but we also observe that the slope of the power law decreases. On the other hand, for the same range of ϵ values, the forward regime scaling is observed to be fairly universal.

Analysis of Short Space–Time-Scale Variability of Oceanic Rain Using TOPEX/Jason

Abstract Information on the spatial and temporal variability of rain rate is important not only for meteorology and hydrology but also for the design of remote sensing and in situ measuring or of millimeter wave communication systems. The Ocean Topography Experiment (TOPEX)/Jason Tandem Mission (TM) collocated rain dataset is used in this study to determine the small space-scale (5 km) and time-scale (70 s) rain variability. TOPEX and Jason dual-frequency (Ku and C bands) radar altimeter data have been extensively used during the past decade to detect and study oceanic precipitations. During the TM, designed to intercalibrate and validate the two altimeters, the two satellites were put on the same orbit with a 70-s time separation. With combined use of altimeter and passive microwave radiometers (also available on board altimeter missions), rain intensity, rain attenuation, rain layer height, rain event length, and surface winds can also be estimated and provide valuable coincident geophysical contextual information. The size of the TM collocated rain database (140 000 samples) is large enough to allow a meaningful statistical analysis of the time–space variability of rain over the World Ocean. The analysis of the different terms contributing to the variability of rain attenuation, from which rain rate is inferred, shows that the geophysical and/or instrumental noise is small enough to allow a meaningful estimation of the variability of the measured rain rate. The analysis of the time and space variabilities and their relation reveals two well-defined regimes. The first one, corresponding to convective rain cells (i.e., rain rate greater than 3–4 mm h−1, length smaller than 50 km, and freezing level greater than 3.5 km), is characterized by high temporal and spatial variabilities (greater than 2–3 mm h−1) that increase with increasing rain intensity and decreasing cell length. Horizontal variability is significantly larger than the temporal one and surface wind has a very limited impact. The second regime corresponds to stratiform and/or weak rain cells. The temporal and spatial variabilities are relatively low (on the order of 1–2 mm h−1) and vary little with rain intensity and cell length. The temporal variability increases with surface wind and largely exceeds the spatial variability (ratio of 2 or more); the ratio strongly increases with increasing wind speed.

Microstructure and viscoelasticity in thermotropic copolyesters: the influence of monomer concentration

This research investigates the influence of monomer composition on the thermal transitions, mi crostructure, and viscoelastic properties of thermotro pic liquid crystalline polymers (LCPs) based on 1, 4-hydroxy-benzoic acid (B) and 2,6-hydroxy-naphthoic acid (N). Compositions B–N of 1:1, 1:3, 3:1, and 2:1 mol% were studied. The solid-to-nematic transition T s→n was greatly influenced by the monomer composition, ranging from 230 to 280 °C. However, the decomposition temperature T dec was independent of composition, all the materials degrading at T dec = 509 °C. Polarized optical microscopy showed a threaded texture in the nematic phase. Fiber X-ray diffraction showed aperiodic meridional maxima for all LCPs, the number of maxima depended on composition. B–N 3:1 and 1:3 mol% favor the orthorhombic crystallographic phase whereas the 1:1 and 2:1 mol% crystallized in a pseudohexagonal phase. Dynamic time sweeps showed that the nematic phases are stable at the temperatures studied. Strain sweeps showed the existence of a linear viscoelastic (LVE) regime. The LVE properties ranged from predominantly viscous (G′ G″) and with a well-defined rubber-like regime for the 1:3 mol% composition, resembling the rheology of flexible polymer melts. The persistence length q appears to be the parameter driving the rheological behavior.

Morphological evolution of voids by surface drift diffusion driven by capillary, electromigration, and thermal-stress gradients induced by steady-state heat flow in passivated metallic thin films and flip chip solder joints. I. Theory

The morphological evolution of intragranular voids induced by surface drift diffusion under the actions of capillary and electromigration (EM) forces and thermal-stress gradients (TSGs) associated with steady-state heat flow is investigated in passivated metallic thin films and flip chip solder joints via computer simulation using the front-tracking method. In the mesoscopic nonequilibrium thermodynamic formulation of the generalized driving forces for the thermal-stress-induced surface drift diffusion, not only the usual elastic strain energy density contribution but also the elastic dipole tensor interaction (EDTI) between the thermal-stress field and the mobile atomic species (monovacancies) are considered using the concept of elastic interaction energy promoted in unified linear instability analysis (ULISA) [T. O. Ogurtani, Phys. Rev. B 74, 155422 (2006)]. According to extensive computer experiments performed on voids, which are initially cylindrical in shape, two completely different and topographically distinct behaviors are observed during the development of quasistationary state void surface morphologies, even in the presence of strong EM forces. These behaviors strictly depend on whether or not heat flux crowding occurs in the regions between the void surface layer and the sidewalls of the interconnect lines due to proximity effects of the insulating boundaries. In both morphological cases, however, one also observes two well-defined regimes, namely, the EM and TSG dominated regimes in EM versus EDTI parametric space. In the case of the TSG dominated regime, the void center of gravity (centroid) exhibits uniform displacement (drift) velocity proportional and opposite to the induced TSG exactly as predicted by ULISA theory. These domains are bounded by a threshold level curve for the EDTI parameter, above which an extremely sharp crack tip nucleation and propagation occurs in the highly localized minima in the triaxial stress regions (i.e., hot spots) surrounding the void surface layer and extending along the longitudinal and off-diagonal directions (flux crowding). The most critical configuration for interconnect failure occurs even when thermal stresses are low if the normalized ratio of interconnect width to void radius is less than 4 (which indicates the onset of heat flux crowding). In the absence of EM this regime manifests itself by the formation of two symmetrically disposed finger-shaped extrusions (pitchfork shaped slits) on the upper and lower shoulders of the void surface on the windward side. In later stages these slits extend with an almost 54° inclination toward the sidewalls, and eventually cause a fatal catastrophic interconnect breakdown due to growth by condensation of supersaturated vacancies in the bulk matrix. At high thermal-stress levels this morphology is replaced by the fracture mode of diffusive-crack formation and propagation. Outside of the heat flux crowding regime and below the TSG threshold levels, the void takes an egg shape pointed toward the high temperature region of the interconnect and steadily drifts against the heat flow (upstream direction) without causing any transgranular damage. Above the TSG threshold levels, however, these modes are replaced by a sharp crack formation regime with an accelerated propagation that may eventually cause open-circuit interconnect failure.

Graphene via largeN: A renormalization group study

We analyze the competing effects of moderate to strong Coulomb electron-electron interactions and weak quenched disorder in graphene. By using a one-loop renormalization group calculation controlled within the large-$N$ approximation, we demonstrate that at successively lower energy (temperature or chemical potential) scales, a type of non-Abelian vector potential disorder always asserts itself as the dominant elastic scattering mechanism for generic short-ranged microscopic defect distributions. Vector potential disorder is tied to both elastic lattice deformations (``ripples'') and topological lattice defects. We identify several well-defined scaling regimes, for which we provide scaling predictions for the electrical conductivity and thermopower, valid when the inelastic lifetime due to interactions exceeds the elastic lifetime due to disorder. Coulomb interaction effects should strongly figure into the physics of suspended graphene films, where ${r}_{s}g1$; we expect the vector potential disorder to play an important role in the description of transport in such films.

Reduction of surface coverage of finite systems due to geometrical steps

The coverage of vicinal, stepped surfaces with molecules is simulated with the help of a two-dimensional Ising model including local distortions and an Ehrlich-Schwoebel barrier term at the steps. An effective two-spin model is capable to describe the main properties of this distorted Ising model. It is employed to analyze the behavior of the system close to the critical points. Within a well-defined regime of bonding strengths and Ehrlich-Schwoebel barriers we find a reduction of coverage (magnetization) at low temperatures due to the presence of the surface step. This results in a second, low-temperature transition besides the standard Ising order-disorder transition. The additional transition is characterized by a divergence of the susceptibility as a finite-size effect. Due to the surface step the mean-field specific heat diverges with a power law.

Characterization of a transient collisional Ni-like molybdenum soft-x-ray laser pumped in grazing incidence

We present experimental results from an extensive investigation of a Ni-like Mo x-ray laser pumped in the transient regime and GRIP configuration (GRazing Incidence Pumping). The pump laser is a 10 Hz, 1 J, Ti:sapphire laser system. The main diagnostic is a monochromatic near-field imaging system with a 1.7 micron spatial resolution that shows the soft-x-ray laser source size and position relative to the target surface. Changes of those characteristics are observed for different GRIP angles, varied between $15\ifmmode^\circ\else\textdegree\fi{}$ and $21\ifmmode^\circ\else\textdegree\fi{}$, while keeping all other parameters constant. Intense lasing is observed routinely at 18.9 nm with up to 3 microjoule output energy and stable operation is demonstrated at 10 Hz. We have investigated the role of several pumping parameters, in particular, the relative energy and delay between the long and short pulse. We show that this multiparameter scan leads to a well-defined optimal regime of operation and better understanding of the GRIP configuration. Finally, as the GRIP scheme requires careful tailoring of the plasma conditions to the specific soft-x-ray laser under investigation, we add a prepulse before the plasma producing long pulse to generate large-scale preplasmas. This increases the brightness of the soft-x-ray beam and leads to an almost Gaussian near-field spatial profile.

Visual Reliability and Information Rate in the Retina of a Nocturnal Bee

Nocturnal animals relying on vision typically have eyes that are optically and morphologically adapted for both increased sensitivity and greater information capacity in dim light. Here, we investigate whether adaptations for increased sensitivity also are found in their photoreceptors by using closely related and fast-flying nocturnal and diurnal bees as model animals. The nocturnal bee Megalopta genalis is capable of foraging and homing by using visually discriminated landmarks at starlight intensities. Megalopta's near relative, Lasioglossum leucozonium, performs these tasks only in bright sunshine. By recording intracellular responses to Gaussian white-noise stimuli, we show that photoreceptors in Megalopta actually code less information at most light levels than those in Lasioglossum. However, as in several other nocturnal arthropods, Megalopta's photoreceptors possess a much greater gain of transduction, indicating that nocturnal photoreceptors trade information capacity for sensitivity. By sacrificing photoreceptor signal-to-noise ratio and information capacity in dim light for an increased gain and, thus, an increased sensitivity, this strategy can benefit nocturnal insects that use neural summation to improve visual reliability at night.

Nanomechanical Properties of Arachidic Acid Langmuir−Blodgett Films

The nanomechanical properties of Langmuir−Blodgett monolayers of arachidic acid extracted at surface pressures of 1, 15, and 35 mN/m and deposited on mica were investigated by atomic force microscopy, force spectroscopy, and lateral force microscopy. It was experimentally demonstrated that the arachidic acid molecular orientation depends on the extraction pressure. According to this, tilting angles of 50, 34, and 22° with respect to the surface perpendicular were detected and identified as conformations that maximize van der Waals interactions between the arachidic acid alkyl chains. The vertical force needed to puncture the monolayers with the AFM tip strongly depends on the molecular tilting angles attained at different monolayer extraction surface pressures, obtaining values that range from 13.07 ± 3.24 nN for 50° to 22.94 ± 5.49 nN for 22° tilting angles. The different molecular interactions involved in the monolayer cohesion are discussed and quantitatively related to the experimental monolayer breakthrough forces. The friction measurements performed from low vertical forces up to monolayer disruption reveal the existence of three well-defined regimes: first, a low friction response due to the elastic deformation of the monolayer, which is followed by a sharp increase in the friction force due to the onset of a sudden plastic deformation. The last regime corresponds to the monolayer rupture and the contact between tip and substrate. The friction coefficient of the substrate is seen to depend on the monolayer extraction pressure, a fact that is discussed in terms of the relationship between the sample compactness and its rupture mechanism.

Mesoscopic Superposition States in Relativistic Landau Levels

We show that a linear superposition of mesoscopic states in relativistic Landau levels can be built when an external magnetic field couples to a relativistic spin 1/2 charged particle. Under suitable initial conditions, the associated Dirac equation produces unitarily superpositions of coherent states involving the particle orbital quanta in a well-defined mesoscopic regime. We demonstrate that these mesoscopic superpositions have a purely relativistic origin and disappear in the nonrelativistic limit.

Fluorescence decay rate statistics of a single molecule in a disordered cluster of nanoparticles

The statistical properties of the fluorescence lifetime of single emitters in disordered systems are discussed. The contribution of radiative and nonradiative processes to the spontaneous decay rate is analyzed using a simple analytical model, in full agreement with exact numerical simulations. The relative fluctuations of the decay rate are shown to exhibit two well-defined regimes dominated either by near-field scattering or by absorption processes. In both regimes, the averaged apparent quantum yield remains high enough to permit practical measurements. Lifetime fluctuations could thus be used a probe of the local environment in complex systems at the nanometer scale.

A closer look at regime shifts based on coastal observations along the eastern boundary of the North Pacific

At least six regime shifts have been reported in the North Pacific since 1920. They occurred in 1925, 1939, 1946, 1976–1977, 1989 and 1999. The major change in 1976–1977 corresponds to a regime shift that is now widely accepted as a canonical event since it had a significant impact on virtually all climatic and ecosystem indicators. We seek to determine if daily sea surface temperature (SST) from Pacific Grove, in central California, and Scripps Pier, in southern California, and coastal observations from several other locations along the west coast of North America can be used to detect and resolve these events. Cumulative sums (CUSUMs) were initially calculated to enhance the detection process. The CUSUM trajectories during the 1976–1977 event at Pacific Grove and Scripps Pier were distinctive, highly correlated, and in phase. The turning point patterns from this event were then used to search for other events that have been reported since 1920. Turning point patterns very similar to the 1976–1977 event were detected in 1946 and 1989. The events in 1925 and 1939 were generally similar, but the CUSUM patterns for the event in 1999 departed significantly from the other events. Further examination of the 1976 and 1989 events revealed inflection points in the CUSUMs near the beginning and end of each transition that correspond to critical values or extrema in the original data. The inflection points and/or critical values provide an improved basis for determining the duration of these events. The robustness of the CUSUM approach for detecting regime shifts was examined by posing the inverse problem to determine if other possible regime changes could be detected that have not been previously reported. The period between 1946 and 1976 was examined, and one match in 1972 was found, which coincided with a large shift in the Aleutian Low Pressure Index. The CUSUM patterns associated with well-defined regime shifts may be essentially unique and thus useful in searching for other events. Whether the temperature ultimately increases or decreases following a regime shift is well-predicted by the sign of the CUSUM slope during an event. Testing regime shifts for statistical significance may be problematic, but our results suggest that when CUSUMs are employed, the detection problem becomes one that is more closely related to pattern recognition where other tests could be applied. CUSUMs often produce a distinct pattern that appears to be characteristic of regime shifts. During well-defined events such as those that occurred in 1946, 1976, and 1989, the CUSUM trajectories from Pacific Grove and Scripps Pier were highly synchronized and nearly identical in form. The CUSUM transformation allows us to identify, localize and observe how these events evolve. We have only been able to examine these events in such detail because daily observations from single locations were used. Based on the events we have examined, they have time scales that range from about 4–9 months. Salinity and sea level data were also employed in this study and were found to be less sensitive to the changes associated with regime shifts than SST. Regime shifts detected in CUSUMs of SST at two locations off Vancouver Island were found to be weaker in amplitude and less well-defined than those detected at Pacific Grove and Scripps Pier. However, they were in phase with the events observed further south. Establishing the connection between these results, and changes in the ecosystems of the North Pacific, should be given a high priority. Finally, the results of this study are related to decadal climate variability and provide additional insight into the nature of this phenomenon.