Effects Of Abrupt Changes Research Articles

Broaden the sound absorption band by using micro-perforated plate back cavities with different cross-sectional areas

In finite size micro-perforated plate structure, the cross-sectional area size of back cavity will affect the resonant frequency of structure. Based on transfer matrix and the characteristics of acoustic propagation in variable cross-section channel, the sound absorption characteristics of the double-layer micro-perforated plate structure with variable cross-section back cavity are studied and analyzed, and a theoretical analysis model of the variable cross-section back cavity micro-perforated plate structure is established. By comparing the theoretical model with the finite element model, the effect of abrupt changes in the cross-sectional area of the back cavity on the noise reduction performance is obtained. As for the double-layer micro-perforated plate in this paper, the bigger the cross-sectional area of back cavity of inner micro-perforated plate, the lower the frequency of first peak absorption coefficient of structure will be and the higher the frequency corresponding to second absorption coefficient peak of structure. Utilizing this feature, a combined micro-perforated plate structure is designed, which has back cavities with different inner cross-sectional areas, and ultimately broadening the structural sound absorption band. Additionally, through using 3D printing technology to produce samples and conducting experimental tests in the impedance tube. Experiments show that the structure can achieve an absorption coefficient of more than 0.8 within the frequency range of 500–1650 Hz, which further improving the noise reduction performance of the MPP structure. The feasibility of variable-sectional back cavity structure for the design of low-frequency and broadband noise reduction absorber is verified.

The Effect of Abrupt Changes to Sources of PM10 and PM2.5 Concentrations in Three Major Agglomerations in Mexico

In the three major urban agglomerations in Mexico (Mexico City, Monterrey, and Guadalajara), a significant change to anthropogenic sources of air pollution happened in March–May 2020, when policies implemented to stop the spread of the COVID-19 virus in Mexico caused the reduction of some anthropogenic sources of air pollution. We study the effect of these significant changes to air pollution sources using satellite-retrieved aerosol optical depth (AOD) and particulate matter (PM10 and PM2.5) concentrations from ground stations. The Chow test was applied to study trend changes in PM concentrations from 1 January to 30 May 2020. The Mann–Whitney non-parametric test was then used to compare average PM concentrations in April and May pre-lockdown, during lockdown in 2020, and post-lockdown in 2021. The assessment was further performed by evaluating the exceedance of national air quality standard maxima. The trend analysis showed that PM10 concentrations were reduced during lockdown in Mexico City and Monterrey, whereas no change was found for PM10 in Guadalajara and PM2.5 in the three cities. Further analysis showed that in Mexico City and Guadalajara, average PM10 and PM2.5 concentrations decreased by 12% in April and May 2020. However, in Monterrey, average PM10 and PM2.5 concentrations increased by 2.76% and 11.07%, respectively, in April 2021 due to a severe drought that caused dry soils and dust around the city. The results of this research can be used to implement policies for reducing anthropogenic sources to improve the air quality in urban areas.

Double-integral sliding mode control of the switched-inductor quasi-Z source boost converter

Compared with the traditional converter, the switching inductance quasi-Z source DC-DC boost converter has the characteristics of wide output voltage, small capacitor size and more reliable circuit. However, in the process of DC voltage boost, the system is prone to high startup impulse voltage, output voltage fluctuation, and other problems. Therefore, a double integral sliding mode control (DISMC) method is proposed. The control method takes the capacitance voltage error, the inductance current error and their sum of single integral and double integral as state variables, and derives the equivalent control law from the sliding mode surface. A Lyapunov function is constructed to analyze the existence conditions of DISMC method. And the effects of abrupt changes of input voltage, negative reference voltage and load power on transient oscillation, steady state error and overshoot of the system are analyzed. This control method solves the non-minimum phase problem of capacitor voltage, so as to improve the start-up performance of the controller and speed up the response of the system. Finally, the superiority and effectiveness of the control method are verified by simulation.

EFL teachers’ identity in self-directed learning: A work-from-home phenomenology

Major potential effects of abrupt changes in educational settings particularly for education stakeholders such as teachers have been somewhat interesting to examine. This study examines how teachers of English as a Foreign Language (EFL) in different schooling levels acclimatize their experiences due to the unanticipated Covid-19 outbreak, which forced them to pursue Online Distance Learning (ODL). Employing a phenomenological approach, eight teachers from various educational and psychometric backgrounds in three different provinces in Indonesia shared their experiences in coping with the changes. Before engaging in two semi-structured interviews, they were invited to complete an e-reflection to share their feelings, concerns, difficulties, and challenges. To get to the core of their experience, the data were scrutinized following an interpretive phenomenological analysis which includes an early focus on the lines of inquiry, central concerns and important themes, identification of shared meanings, final interpretations, and the dissemination of the interpretations. The findings demonstrated that the changes created an ambivalent experience of being challenged and bored, prompting teachers to reflect on their existing practice and respond appropriately by combining empathy, new roles, and technology paramount through their self-directed learning (SDL). Further implications on teacher agency and identity are discussed to shed light on the reshaping of teacher identities due to ODL and SDL.

The dynamics of auditory stream segregation: Effects of sudden changes in frequency, level, or modulation.

Three experiments explored the effects of abrupt changes in stimulus properties on streaming dynamics. Listeners monitored 20-s-long low- and high-frequency (LHL-) tone sequences and reported the number of streams heard throughout. Experiments 1 and 2 used pure tones and examined the effects of changing triplet base frequency and level, respectively. Abrupt changes in base frequency (±3-12 semitones) caused significant magnitude-related falls in segregation (resetting), regardless of transition direction, but an asymmetry occurred for changes in level (±12 dB). Rising-level transitions usually decreased segregation significantly, whereas falling-level transitions had little or no effect. Experiment 3 used pure tones (unmodulated) and narrowly spaced (±25 Hz) tone pairs (dyads); the two evoke similar excitation patterns, but dyads are strongly modulated with a distinctive timbre. Dyad-only sequences induced a strongly segregated percept, limiting scope for further build-up. Alternation between groups of pure tones and dyads produced large, asymmetric changes in streaming. Dyad-to-pure transitions caused substantial resetting, but pure-to-dyad transitions sometimes elicited even greater segregation than for the corresponding interval in dyad-only sequences (overshoot). The results indicate that abrupt changes in timbre can strongly affect the likelihood of stream segregation without introducing significant peripheral-channeling cues. These asymmetric effects of transition direction are reminiscent of subtractive adaptation in vision.

Effect of Abrupt Changes in the Cross-Sectional Area of a Pipe on Flame Propagation Characteristics of CH4/Air Mixtures.

To study the flame propagation characteristics of methane/air premixed gas in the pipeline with a sudden change of the pipe cross-sectional area, six kinds of customized pipes are used to study the methane/air premixed gas with a concentration of 9.5%. The results show that when the initial smooth flame front encounters an abrupt change in the cross-sectional area, the flame front becomes disordered and a turbulent flame is formed. A greater change in the cross-sectional area results in more severe flame turbulence. Compared with larger cross-section pipes set at the ignition end and downstream end, when the large cross-sectional area pipe is set in the middle of the pipe, the flame propagation process receives the secondary mutation induction effect of the abrupt cross section and the turbulence effect is stronger. The maximum propagation velocity and pressure are observed in configuration with the larger pipe in the middle of the pipe network. Moreover, when the cross-sectional area of this larger pipe increases, the flame is more substantially influenced by longitudinal expansion, the maximum propagation velocity and maximum overpressure increase accordingly, and the pressure oscillations are more obvious.

Regional subglacial quarrying and abrasion below hard‐bedded palaeo‐ice streams crossing the Shield–Palaeozoic boundary of central Canada: the importance of substrate control

Three‐dimensional surface visualization models derived from high‐resolution LiDAR data provide new information about the type and scale of erosional processes below Late Wisconsin palaeo‐ice streams traversing the boundary between Canadian Shield crystalline rocks with offlapping Palaeozoic limestones in central Ontario. The hard bed is directly analogous to that found below ice streams in East Antarctica and East Greenland and provides insight into the effects of abrupt changes in substrate type on subglacial processes. Erosion of hard crystalline Canadian Shield rock was largely ineffectual consisting of areal abrasion of rounded whalebacks and local lee side plucking. In contrast, fast flow over the strike of gently dipping well‐bedded and jointed Palaeozoic limestones cut large flow‐parallel grooves and ridges akin to mega‐scale glacial lineations reflecting intense abrasion below narrow streams of subglacial debris dominated by hard crystalline Shield clasts (erodents). Regionally extensive plucking of structurally weak, well‐jointed and bedded limestone produced large volumes of rubbly carbonate debris leaving a 25‐km‐wide belt of uncontrolled hummocky rubble terrain (long known as the Dummer Moraine in Southern Ontario) some 350 km long and locally as much as 10 m thick. Subglacial plucking and abrasion under fast flowing ice were highly effective in stripping limestone cover rocks from Precambrian basement, and over many glacial cycles, may have played a role in the location and excavation of numerous large and deep lake basins around the Shield–Palaeozoic boundary zone in North America.

TRILEMMA POLICY PATHS AND REAL OUTPUT NEXUS IN NIGERIA

This study examined the nexus between the policy trilemma and its effects on real out-put in Nigeria. The study employed annual data spanning from 1990 to 2017. Interna-tional reserve has been included in the model due to its importance as noted in the literature. Following Hsing (2012) and Ajogbeje, Adeniyi and Egwaikhide (2018), Vector Autoregression (VAR) model was employed and specifically Autoregressive Distributed Lag (ARDL) bound test for cointegration was used. Data for the study was obtained from Aizenman, Chinn and Ito (2013), CBN Statistical Database and IMF International Financial Statistics Database. The study found a mix significant results between exchange rate stability and real GDP. The study further revealed that both monetary policy independence and capital account liberalization independently exert a significant and positive impact on real GDP but interactively they significantly re-duce the level of real output in the economy. The nexus between international reserve and real GDP was positive and significant. Therefore, the study recommends that for Nigeria to feel the positive impact of her trilemma choice on the economy, policy mak-ers should strive to pursue the policy combination consistently and buffered the econ-omy with a robust external reserve to cushion the effects of abrupt change in capital flow and exchange rate shocks.

Simple 2D gravity–density inversion for the modeling of the basin basement: example from the Banat area, Serbia

We have developed a technique to calculate lateral density distribution of the sedimentary basin basement by combining linear gravity–density inversion and 2D forward modeling. The procedure requires gravity anomaly data, depth-to-basement data and density data for the sediments (density–depth distribution). Gravity effect of density variations in the basement was extracted from the total gravity anomaly by removing the joint effect of the sediments with vertical density variations and homogeneous basement of average density contrast (calculated by 2D modeling). Gravity effect of the sediments was calculated using depth-to-basement data and density–depth function, based on borehole logging data. Bouguer slab formula was used in order to simplify basement model and calculate the operator for the linear inversion of gravity effect of the basement into lateral density distribution. The results were tested by forward modeling, and differences between observed and modeled gravity data were used for the next iteration of the inversion and correction of density values in each point along the profile. The procedure was tested using synthetic models and field example, and both results were satisfying, especially taking into account the simplicity of the inversion technique. The main problem was the effect of abrupt changes in the basement topography on density distribution, but it was downsized by filtering. Basement density maps were compiled based upon the density distribution along the profiles.

Predictable hydrological and ecological responses to Holocene North Atlantic variability

Climate variations in the North Atlantic region can substantially impact surrounding continents. Notably, the Younger Dryas chronozone was named for the ecosystem effects of abrupt changes in the region at circa (ca.) 12.9-11.7 ka (millennia before 1950 AD). Holocene variations since then, however, have been hard to diagnose, and the responsiveness of terrestrial ecosystems continues to be debated. Here, we show that Holocene climate variations had spatial patterns consistent with changes in Atlantic overturning and repeatedly steepened the temperature gradient between Nova Scotia and Greenland since >8 ka. The multicentury changes correlated with hydrologic and vegetation changes in the northeast United States, including when an enhanced temperature gradient coincided with subregional droughts indicated by water-level changes at multiple coastal lakes at 4.9-4.6, 4.2-3.9, 2.8-2.1, and 1.3-1.2 ka. We assessed the variability and its effects by replicating signals across sites, using converging evidence from multiple methods, and applying forward models of the systems involved. We evaluated forest responses in the northeast United States and found that they tracked the regional climate shifts including the smallest magnitude (∼5% or 50 mm) changes in effective precipitation. Although a long-term increase in effective precipitation of >45% (>400 mm) could have prevented ecological communities from equilibrating to the continuously changing conditions, our comparisons confirm stable vegetation-climate relationships and support the use of fossil pollen records for quantitative paleoclimate reconstruction. Overall, the network of records indicates that centennial climate variability has repeatedly affected the North Atlantic region with predictable consequences.

Analytic solution for reflection and transmission coefficients of joints in three-dimensional truss-type structural networks

This paper presents an analytic solution method to evaluate transient response of the joints in the truss-type structural networks. The analytic method models the wave propagation along the elastic members connected to the joints and derives the functions for the reflection and transmission coefficients for the structural joints. The coefficients of wave reflection and transmission across the joints are functions of material properties and geometrical parameters of the elements connected to the joint. The present analytic solution considers the effects of abrupt change in material properties as well as the alignment of connected elements on the transmission and reflection coefficients of the joints. The analytic solution method derives the functions for the transmission and reflection coefficients at the connection point of two different coaxial elements as well as the joints in planar and space frame structures.

Disconnected submarine lobes as a record of stepped slope evolution over multiple sea-level cycles

The effects of abrupt changes in slope angle and orientation on turbidity current behavior have been investigated in numerous physical and numerical experiments and examined in outcrop, subsurface, and modern systems. However, the long-term impact of subtle and evolving seabed topography on the stratigraphic architecture of deep-water systems requires fine-scale observations and extensive 3-D constraints. This study focuses on the Permian Laingsburg and Fort Brown formations, where multiple large sand-rich systems (Units A–F) have been mapped from entrenched slope valleys, through channel-levee systems, to basin-floor lobe complexes over a 2500 km2 area. Here, we investigate three thinner (typically <5 m in thickness) and less extensive sand-rich packages, Units A/B, B/C, and D/E, between the large-scale systems. Typically, these sand-rich units are sharp-based and topped, and contain scours and mudstone clast conglomerates that indicate deposition from high-energy turbidity currents. The mapped thickness and facies distribution suggest a lobate form. These distinctive units were deposited in similar spatial positions within the basin-fill and suggest similar accommodation patterns on the slope and basin floor prior to the larger systems (B, C, and E). Stratigraphically, these thin units represent the first sand deposition following ­major periods of shut-down in sediment supply, and are interpreted as marking a partial re-establishment of sand delivery pathways creating “disconnected lobes” that are fed mainly by flows sourced from failures on the shelf and upper slope rather than major feeder channel-levee systems. Thickness and facies patterns throughout the deep-water stratigraphy suggest seabed topography was present early in the basin formation and maintained persistently in a similar area to ultimately form a stepped slope profile. The stepped slope profile evolved through three key stages of development: Phase 1, where sediment supply exceeds deformation rate (likely caused by differential subsidence); Phase 2, where sediment supply is on average equal to deformation rate; and Phase 3, where deformation rate outpaces sediment supply. This study demonstrates that smaller systems are a sensitive record of evolving seabed topography and they can consequently be used to recreate more accurate paleotopographic profiles.

Electrical and morphological properties of microinjection molded polypropylene/carbon nanocomposites

ABSTRACTA series of different carbon (carbon black, carbon nanotubes, and graphite nanoplatelets) filled polypropylene nanocomposites were prepared by melt blending, then followed by compression molding or microinjection molding (µIM). Direct current electrical conductivity measurements and melt rheology tests were utilized to detect the percolated structure for compression molded polypropylene/carbon nanocomposites. For µIM, a rectangular mold insert which has a three‐step decrease in thickness along the flow direction was adopted to study the effect of abrupt changes in mold geometry on the electrical and morphological properties of subsequent micromoldings (µ‐moldings). Results indicated that the µ‐moldings exhibited a higher percolation threshold when compared with their compression molded counterparts. This is largely due to the severe shearing conditions that prevail in the µIM process. The morphology of µ‐moldings containing different carbon fillers was examined using scanning electron microscopy. The development of corresponding microstructure is found to be strongly dependent on the types of carbon fillers used in µIM, which is crucial to the enhancement of electrical conductivity for the resulting µ‐moldings. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45462.

A local scattering approach for the effects of abrupt changes on boundary-layer instability and transition: a finite-Reynolds-number formulation for isolated distortions

We investigate the influence of abrupt changes on boundary-layer instability and transition. Such changes can take different forms including a local porous wall, suction/injection and surface roughness as well as junctions between rigid and porous walls. They may modify the boundary conditions and/or the mean flow, and their effects on transition have usually been assessed by performing stability analysis for the modified base flow and/or boundary conditions. However, such a conventional local linear stability theory (LST) becomes invalid if the change occurs over a relatively short scale comparable with, or even shorter than, the characteristic wavelength of the instability. In this case, the influence on transition is through scattering with the abrupt change acting as a local scatter, that is, an instability mode propagating through the region of abrupt change is scattered by the strong streamwise inhomogeneity to acquire a different amplitude. A local scattering approach (LSA) should be formulated instead, in which a transmission coefficient, defined as the ratio of the amplitude of the instability wave after the scatter to that before, is introduced to characterize the effect on instability and transition. In the present study, we present a finite-Reynolds-number formulation of LSA for isolated changes including a rigid plate interspersed by a local porous panel and a wall suction through a narrow slot. When the weak non-parallelism of the unperturbed base flow is ignored, the local scattering problem can be cast as an eigenvalue problem, in which the transmission coefficient appears as the eigenvalue. We also improved the method to take into account the non-parallelism of the unperturbed base flow, where it is found that the weak non-parallelism has a rather minor effect. The general formulation is specialized to two-dimensional Tollmien–Schlichting (T–S) waves. The resulting eigenvalue problem is solved, and full direct numerical simulations (DNS) are performed to verify some of the predictions by LSA. A parametric study indicates that conventional LST is valid only when the change is sufficiently gradual, and becomes either inaccurate or invalid when the scale of the local distortion is short. A local porous panel enhances T–S waves, while a local suction with a moderate mass flux significantly inhibits T–S waves. In the latter case, a comprehensive comparison is made between the theoretical predictions and experimental data, and a satisfactory quantitative agreement was observed.

Ring-Shaped Microlanes and Chemical Barriers as a Platform for Probing Single-Cell Migration.

Quantification and discrimination of pharmaceutical and disease-related effects on cell migration requires detailed characterization of single-cell motility. In this context, micropatterned substrates that constrain cells within defined geometries facilitate quantitative readout of locomotion. Here, we study quasi-one-dimensional cell migration in ring-shaped microlanes. We observe bimodal behavior in form of alternating states of directional migration (run state) and reorientation (rest state). Both states show exponential lifetime distributions with characteristic persistence times, which, together with the cell velocity in the run state, provide a set of parameters that succinctly describe cell motion. By introducing PEGylated barriers of different widths into the lane, we extend this description by quantifying the effects of abrupt changes in substrate chemistry on migrating cells. The transit probability decreases exponentially as a function of barrier width, thus specifying a characteristic penetration depth of the leading lamellipodia. Applying this fingerprint-like characterization of cell motion, we compare different cell lines, and demonstrate that the cancer drug candidate salinomycin affects transit probability and resting time, but not run time or run velocity. Hence, the presented assay allows to assess multiple migration-related parameters, permits detailed characterization of cell motility, and has potential applications in cell biology and advanced drug screening.

Could Have Gone Wrong: Effects of Abrupt Changes in Migratory Behaviour on Harvest in a Waterbird Population.

To sustainably exploit a population, it is crucial to understand and reduce uncertainties about population processes and effects of harvest. In migratory species, management is challenged by geographically separated changing environmental conditions, which may cause unexpected changes in species distribution and harvest. We describe the development in the harvest of Svalbard-breeding pink-footed geese (Anser brachyrhynchus) in relation to the observed trajectory and migratory behaviour of the population. In autumn, geese migrate via stopover sites in Norway and Denmark (where they are hunted) to wintering grounds in the Netherlands and Belgium (where they are protected). In Denmark and Norway harvesting increased stepwise during the 2000s. The increase in the population size only partly explained the change. The change corresponded to a simultaneous stepwise increase in numbers of geese staging in Denmark throughout autumn and winter; geese also moved further inland to feed which collectively increased their exposure to hunting. In Norway the increase in harvest reflected greater utilisation of lowland farmland areas by geese, increasing their hunting exposure. The study demonstrates how changes in migratory behaviour can abruptly affect exposure to hunting, which showed a functional response to increased temporal and spatial availability of geese. The harvest has now reached a level likely to cause a population decline. It highlights the need for flexible, internationally coordinated hunting regulations and reliable up-to-date population estimates and hunting bag statistics, which are rare in European management of migratory waterbirds. Without such information decisions are left with judgments based on population estimates, which often have time lags of several years between recording and reporting, hampering possibilities for the timely adjustment of management actions.

Screening key parameters related to passive system performance based on Analytic Hierarchy Process

Passive safety system is widely used in the new generation nuclear power plant (NPP) designs such as AP1000 to improve the reactor safety benefitting from its simple construction and less request for human intervene. However, the functional failure induced by uncertainty in the system thermal–hydraulic (T–H) performance becomes one of the main contributors to system operational failure since the system operates based on natural circulation, which should be considered in the system reliability evaluation. In order to improve the calculation efficiency the key parameters which significantly affect the system T–H characteristics can be screened and then be analyzed in detail. The Analytical Hierarchy Process (AHP) is one of the efficient methods to analyze the influence of the parameters on a passive system based on the experts’ experience. The passive containment cooling system (PCCS) in AP1000 is one of the typical passive safety systems, nevertheless too many parameters need to be analyzed and the T–H model itself is more complicated, so the traditional AHP method should be mended to use for screening key parameters efficiently. In this paper, we adapt the improved method in hierarchy construction and experts’ opinions integration, some parameters at the bottom justly in the traditional hierarchy are studied as criterion layer in improved AHP, the rationality of the method and the effect of abrupt change with the data are verified. The passive containment cooling system (PCCS) in AP1000 is evaluated as an example, and four key parameters are selected from 49 inputs.

How sensitive is the CWSI to changes in solar radiation?

Cloud cover drastically and instantaneously reduces net radiation and available energy. Appearance of clouds will therefore alter the surface energy balance and elicit response of plant canopy temperature (T C). The attenuated shortwave radiation and altered T C during the presence of clouds may subsequently affect the crop water stress index (CWSI). Therefore, to correctly interpret T C measurements, the effect of clouds must be understood. The objective of this work was to study the effect of abrupt changes in solar radiation due to varying cloudy conditions on T C and CWSI for olive trees. Results from two separate experiments are presented, both comparing different levels of water status of Barnea olive trees. The first experiment was conducted in a commercial orchard where five irrigation levels were applied. Thermal images were acquired simultaneously with stomatal resistance measurements on a day with clear skies. The second experiment was conducted on single trees planted in lysimeters. Irrigation was withheld for five of 15 trees for 6 days until they were severely stressed. Thereafter, irrigation was resumed to levels higher than the transpiration rates. Throughout the stress and recovery periods, water status measurements were conducted daily between 12:00 and 14:00 on all trees. On the day of maximum stress, thermal images of well-watered and stressed trees were acquired every minute throughout a time sequence during which large fluctuations in radiation due to cloud cover were observed. The most pronounced result of this study was the greater response of stressed, compared to well-watered, trees to abrupt changes in radiation intensity. When solar radiation was high, the CWSI of stressed trees reached 0.8, while the CWSI of well-watered trees was near 0. When solar radiation dropped due to clouds, the CWSI of the stressed trees decreased to ∼0.3, while that of well-watered trees continued to fluctuate around 0. This finding implies that application of thermal imagery for water status detection would require very high radiometric resolution and constant reference measurements. For routine monitoring in commercial olive orchards, this could be facilitated by strategic maintenance of a few well-watered trees.

Torsional Strain of Long Steam Turbine Blades

Long naturally twisted blades of steam turbines during the operation experience the aggregate stress-strain state. The strain of the elastic bootstrapping, which is a function of the geometry of the blade and the impact of centrifugal forces developed by it, in turn, causes the shear stresses, the distribution of which along the blade height has not been reflected in the press.The article presents the results of the study of the effect of smoothness of the derivative of natural blade twist angles in the initial state on the nature of the distribution of shear stresses caused by the elastic bootstrapping in sections of the blade.The influence of different kinds of errors (design, production) on the growth of additional shear stresses was determined. The effect of abrupt changes of the derivative of the angle of the natural twist on the nature of the elastic bootstrapping of the blade was revealed.The article provides recommendations to reduce the additional shear stresses caused by a violation of the smoothness of natural twist angles, as well as to compensate for deviations from the design values of the natural twist angles in the process

Abrupt climate change: Mechanisms, patterns, and impacts

In the span of only a few decades, the global temperature can soar by more than a dozen degrees Celsius, a feat that 20 years ago was considered improbable, if not impossible. But recent research in the nascent field of rapid climate change has upended the dominant views of decades past. Focusing primarily on events during and after the most recent glaciation, from 80,000 years ago, the AGU monograph Abrupt Climate Change: Mechanisms, Patterns, and Impacts, edited by Harunur Rashid, Leonid Polyak, and Ellen Mosley‐Thompson, explores the transient climate transitions that were only recently uncovered in climate proxies around the world. In this interview, Eos talks to Harunur Rashid about piecing together ancient climes, the effect of abrupt change on historical civilizations, and why younger researchers may be more worried about modern warming than their teachers.