Parallel Shift Research Articles

Decimation by sea star wasting disease and rapid genetic change in a keystone species, Pisaster ochraceus

Standing genetic variation enables or restricts a population's capacity to respond to changing conditions, including the extreme disturbances expected to increase in frequency and intensity with continuing anthropogenic climate change. However, we know little about how populations might respond to extreme events with rapid genetic shifts, or how population dynamics may influence and be influenced by population genomic change. We use a range-wide epizootic, sea star wasting disease, that onset in mid-2013 and caused mass mortality in Pisaster ochraceus to explore how a keystone marine species responded to an extreme perturbation. We integrated field surveys with restriction site-associated DNA sequencing data to (i) describe the population dynamics of mortality and recovery, and (ii) compare allele frequencies in mature P. ochraceus before the disease outbreak with allele frequencies in adults and new juveniles after the outbreak, to identify whether selection may have occurred. We found P. ochraceus suffered 81% mortality in the study region between 2012 and 2015, and experienced a concurrent 74-fold increase in recruitment beginning in late 2013. Comparison of pre- and postoutbreak adults revealed significant allele frequency changes at three loci, which showed consistent changes across the large majority of locations. Allele frequency shifts in juvenile P. ochraceus (spawned from premortality adults) were consistent with those seen in adult survivors. Such parallel shifts suggest detectable signals of selection and highlight the potential for persistence of this change in subsequent generations, which may influence the resilience of this keystone species to future outbreaks.

A cerebellar substrate for cognition evolved multiple times independently in mammals.

Given that complex behavior evolved multiple times independently in different lineages, a crucial question is whether these independent evolutionary events coincided with modifications to common neural systems. To test this question in mammals, we investigate the lateral cerebellum, a neurobiological system that is novel to mammals, and is associated with higher cognitive functions. We map the evolutionary diversification of the mammalian cerebellum and find that relative volumetric changes of the lateral cerebellar hemispheres (independent of cerebellar size) are correlated with measures of domain-general cognition in primates, and are characterized by a combination of parallel and convergent shifts towards similar levels of expansion in distantly related mammalian lineages. Results suggest that multiple independent evolutionary occurrences of increased behavioral complexity in mammals may at least partly be explained by selection on a common neural system, the cerebellum, which may have been subject to multiple independent neurodevelopmental remodeling events during mammalian evolution.

Taxon-Function Decoupling as an Adaptive Signature of Lake Microbial Metacommunities Under a Chronic Polymetallic Pollution Gradient.

Adaptation of microbial communities to anthropogenic stressors can lead to reductions in microbial diversity and disequilibrium of ecosystem services. Such adaptation can change the molecular signatures of communities with differences in taxonomic and functional composition. Understanding the relationship between taxonomic and functional variation remains a critical issue in microbial ecology. Here, we assessed the taxonomic and functional diversity of a lake metacommunity system along a polymetallic pollution gradient caused by 60 years of chronic exposure to acid mine drainage (AMD). Our results highlight three adaptive signatures. First, a signature of taxon—function decoupling was detected in the microbial communities of moderately and highly polluted lakes. Second, parallel shifts in taxonomic composition occurred between polluted and unpolluted lakes. Third, variation in the abundance of functional modules suggested a gradual deterioration of ecosystem services (i.e., photosynthesis) and secondary metabolism in highly polluted lakes. Overall, changes in the abundance of taxa, function, and more importantly the polymetallic resistance genes such as copA, copB, czcA, cadR, cCusA, were correlated with trace metal content (mainly Cadmium) and acidity. Our findings highlight the impact of polymetallic pollution gradient at the lowest trophic levels.

Effects of climate shocks on human fertility in Indonesia: a retrospective, panel analysis of household survey and climate data

BackgroundClimate change is likely to induce a large range of household-level responses, including changes in human fertility behaviours and outcomes. These responses might have important implications for human and economic development, women's empowerment, and environmental sustainability. However, to date, few studies have explored the associations between climate change and fertility intentions, family planning use, and births. MethodsDrawing on the literature linking climate variability to rice production in Indonesia, we used large-scale, longitudinal household survey data and high-resolution climate data to explore changes in childbearing preferences, family planning use, and births after community-level climate anomalies (timing of monsoon onset and temperature) in Indonesia between 1993 and 2015. Analyses were done with a series of fixed-effects, logistic regression models. We also assessed parallel shifts in household wellbeing, as measured by expenditure on rice, food, and non-food products. FindingsWe found that, in the short term (climate anomalies occurring 1–12 months before surveys), fertility desires increased and family planning use declined in response to delays in monsoon onset, particularly in wealthier populations. Delays in monsoon onset were also associated with substantially reduced expenditure on food and non-food products among households without farm businesses and high levels of education. In the medium term (climate anomalies occurring 1–60 months before surveys), fertility desires declined and family planning use increased in response to high temperatures, particularly in poorer populations. InterpretationThese results suggest that fertility desires, family planning use, and births are affected by climate shocks. Provision of high-quality family planning services can serve as an important climate change adaptation tool for vulnerable populations. FundingNone.

'Beauty is Truth and Truth Beauty': How Intuitive Insights Shape Legal Reasoning and the Rule of Law

Scientists have long recognized two distinct forms of human thought. “Type 1” reasoning is unconscious, intuitive, and specializes in finding complex patterns. It is typically associated with the aesthetic emotion that John Keats called “beauty.” “Type 2” reasoning is conscious, articulable, and deductive. Scholars usually assume that legal reasoning is entirely Type 2. However, critics from Holmes to Posner have protested that unconscious and intuitive judgments are at least comparably important. This article takes the conjecture seriously by asking what science can add to our understanding of how lawyers and judges interpret legal texts. This is a good time to take stock. Recent advances in cognitive psychology, brain imaging, and neural network theory have already pushed many humanities scholars to rethink postmodern interpretations that privilege politics and culture over texts. This article argues that a parallel shift is overdue in law and that Type 1 reasoning, which specializes in pattern recognition, provides a natural explanation for how judges choose among competing legal theories. Finally, and most surprisingly, the article documents cognitive psychology evidence showing that Type 1 judgments show significant universality, i.e. that humans who study subjects for long periods often make similar choices without regard to the societies they were born into. This solves a long-standing difficulty in jurisprudence, which often struggles to explain why one legal interpretation should be more convincing than another. The rest of the article analyzes how Type 1 thinking enters into legal reasoning and outcomes. It begins by reviewing 19th Century theories that claimed a leading role for intuitive reasoning in public policy. It then updates these theories to accommodate the relatively weak statistical correlations that psychologists have documented, arguing that modern court systems amplify these signals in approximately determinate ways. It also explains why advocates should rationally prefer formalist judges to pragmatic ones. Crucially, the existence of universality implies a measure of agreement across all lawyers regardless of personal bias or politics. This common ground gives judges a reliably neutral basis for deciding cases.

Research on Integrated Control Method of Tiltrotor with Variable Rotor Speed Based on Two-Speed Gearbox

Abstract The process of rotor speed variation under tiltrotor cruise state has been studied, and the integrated variable speed control method of tiltrotor based on two-speed gearbox is proposed. Firstly, a nonlinear model predictive controller (NMPC) based on state variable model of the component-level model of the turboshaft engine is designed. Then based on the integrated engine model, the two-speed dual path tiltrotor driveline comprehensive simulation model was developed by utilizing gear kinematics theory, blade element analysis and the theory of classical mechanics. Finally, both a Parallel Shift Control (PSC) strategy and a Sequential Shift Control (SSC) strategy in tiltrotor cruise state were analyzed and compared with conventional PID controller. It is shown that the rotors’ speed can synchronously vary by 50 percent under the PSC strategy in tiltrotor cruise state. Meanwhile, disengaging the engine in turn by freewheel clutches can reduce the rotors’ speed from 190 rpm to 102.5 rpm along the specified path under the SSC strategy. The overshoot and droop amount of the power turbine speed can be reduced to less than 1.5 % with the steady error no more than 0.2 % through NMPC, which realizes the fast response control of the turboshaft engine.

Plasmon Geometric Phase and Plasmon Hall Shift

The collective plasmonic modes of a metal comprise a pattern of charge density and tightly-bound electric fields that oscillate in lock-step to yield enhanced light-matter interaction. Here we show that metals with non-zero Hall conductivity host plasmons with a fine internal structure: they are characterized by a current density configuration that sharply departs from that of ordinary zero Hall conductivity metals. This non-trivial internal structure dramatically enriches the dynamics of plasmon propagation, enabling plasmon wavepackets to acquire geometric phases as they scatter. Strikingly, at boundaries these phases accumulate allowing plasmon waves that reflect off to experience a non-reciprocal parallel shift along the boundary displacing the incident and reflected plasmon trajectories. This plasmon Hall shift, tunable by Hall conductivity as well as plasmon wavelength, displays the chirality of the plasmon's current distribution and can be probed by near-field photonics techniques. Anomalous plasmon dynamics provide a real-space window into the inner structure of plasmon bands, as well as new means for directing plasmonic beams.

An approach to correlate fatigue crack growth rate with S-N curve for an aluminum alloy LY12CZ

By considering fatigue crack growth (FCG) as the consequence of fatigue fracture of crack front, the correlation between crack growth rate and S-N curve has been investigated. A method to calculate the fatigue life of crack front from the S-N curve has been developed by taking the initial damage at the crack front into account. It is found that the effect of initial damage on fatigue life can be approximately expressed by a parallel shift of S-N curve in bi-logarithmic graph. Thus, crack growth rate curve corresponding to an initial damage at crack front, can also be obtained by a parallel shift of the base curve, which can be calculated from the imaginary fatigue life of crack front without initial damage. The shift distance is dependent on the initial damage at crack front, and can be determined by just one or several experimental results of crack growth. Thereby, the test numbers to obtain crack growth curve can be reduced greatly by adopting this correlation.

Adaptive Supplementary Damping Control of VSC-HVDC for Interarea Oscillation Using GrHDP

Interarea oscillation is one of the main challenges for the secure and stable operation of a large-scale interconnected power system. To address this problem, this paper presents an adaptive supplementary damping controller (SDC) for voltage source converter based high voltage direct current (VSC-HVDC) by using the goal representation heuristic dynamic programming (GrHDP). Compared with conventional heuristic dynamic programming (HDP), GrHDP adds a new goal representation network to generate an adaptive reward signal to achieve better mapping relationship between the system states and the control action. To compensate phase shift between the output and input signals of a large-scale interconnected AC/DC power system, this paper proposes a parallel phase shift channel for the GrHDP. Moreover, the proposed GrHDP-SDC is a model-free control scheme, which does not need the mathematic model of the power system and has quick online learning ability to adapt to the variation of system operating conditions. Case studies are carried out on the 10-machine 39-bus system and 16-machine 68-bus system, respectively. Compared with the conventional lead-lag SDC (LL-SDC) and HDP-SDC, simulation results show that the proposed GrHDP-SDC can always provide satisfactory damping performance over a wide range of system operating conditions and disturbances.

Linking Hadley Circulation and Storm Tracks in a Conceptual Model of the Atmospheric Energy Balance

Abstract Midlatitude storm tracks shift in response to climate change and natural climate variations such as El Niño, but the dynamical mechanisms controlling these shifts are not well established. This paper develops an energy balance model that shows how shifts of the Hadley cell terminus and changes of the meridional energy flux out of the Hadley cell can drive shifts of storm tracks, identified as extrema of the atmospheric meridional eddy energy flux. The distance between the Hadley cell terminus and the storm tracks is primarily controlled by the energy flux out of the Hadley cell. Because tropical forcings alone can modify the Hadley cell terminus, they can also shift extratropical storm tracks, as demonstrated through simulations with an idealized GCM. Additionally, a strengthening of the meridional temperature gradient at the terminus and hence of the energy flux out of the Hadley cell can reduce the distance between the Hadley cell terminus and the storm tracks, enabling storm-track shifts that do not parallel shifts of the Hadley cell terminus. Thus, with the aid of the energy balance model and supporting GCM simulations, a closed theory of storm-track shifts emerges.

Implementation of the parallel mean shift-based image segmentation algorithm on a GPU cluster

ABSTRACTThe mean shift image segmentation algorithm is very computation-intensive. To address the need to deal with a large number of remote sensing (RS) image segmentations in real-world applications, this study has investigated the parallelization of the mean shift algorithm on a single graphics processing unit (GPU) and a task-scheduling method with message passing interface (MPI)+OpenCL programming model on a GPU cluster platform. This paper presents the test results of the parallel mean shift image segmentation algorithm on Shelob, a GPU cluster platform at Louisiana State University, with different datasets and parameters. The experimental results show that the proposed parallel algorithm can achieve good speedups with different configurations and RS data and can provide an effective solution for RS image processing on a GPU cluster.

Adapting to large-scale changes in Advanced Placement Biology, Chemistry, and Physics: the impact of online teacher communities

ABSTRACTOver the past decade, the field of teacher professional learning has coalesced around core characteristics of high quality professional development experiences (e.g. Borko, Jacobs, & Koellner, 2010. Contemporary approaches to teacher professional development. In P. L. Peterson, E. Baker, & B. McGaw (Eds.), International encyclopedia of education (Vol. 7, pp. 548–556). Oxford: Elsevier.; Darling-Hammond, Hyler, & Gardner, 2017. Effective teacher professional development. Palo Alto, CA: Learning Policy Institute). Many countries have found these advances of great interest because of a desire to build teacher capacity in science education and across the full curriculum. This paper continues this progress by examining the role and impact of an online professional development community within the top-down, large-scale curriculum and assessment revision of Advanced Placement (AP) Biology, Chemistry, and Physics. This paper is part of a five-year, longitudinal, U.S. National Science Foundation–funded project to study the relative effectiveness of various types of professional development in enabling teachers to adapt to the revised AP course goals and exams. Of the many forms of professional development our research has examined, preliminary analyses indicated that participation in the College Board's online AP Teacher Community (APTC) – where teachers can discuss teaching strategies, share resources, and connect with each other – had positive, direct, and statistically significant association with teacher self-reported shifts in practice and with gains in student AP scores (Fishman et al., 2014). This study explored how usage of the online APTC might be useful to teachers and examined a more robust estimate of these effects. Findings from the experience of AP teachers may be valuable in supporting other large-scale curriculum changes, such as the U.S. Next Generation Science Standards or Common Core Standards, as well as parallel curricular shifts in other countries.

Stress-induced crystal transition of poly(butylene succinate) studied by terahertz and low-frequency Raman spectroscopy and quantum chemical calculation

We measured terahertz (THz) and low-frequency Raman spectra of Poly (butylene succinate) (PBS) which shows the crystal transition from α to β by stretching. For the assignment of the absorption peaks in the low-frequency region, we performed quantum chemical calculations with Cartesian-coordinate tensor transfer (CCT) method. Four major peaks appeared in the THz spectra of PBS at around 58, 76, 90, and 100cm−1, and in the low-frequency Raman spectra a peak was observed at 88cm−1. The THz peak at 100cm−1 and the Raman peak at 88cm−1 show a shift to a lower wavenumber region with increasing temperature. The quantum chemical calculation of β crystal form reveals the new peak appears above 100cm−1. It was found that two kinds of peaks overlapped at around 100cm−1 in the THz spectra of PBS. One of them can be assigned to a weak hydrogen bond between the C=O and CH2 groups in the intermolecular chains, which is perpendicular to the molecular chain of the α crystal form. Another one showed a parallel polarization which can be assigned to the intramolecular interaction between O (ether) and H-C groups in the β crystal form. The position of the peak at around 100cm−1 in the perpendicular polarization changed to a lower wavenumber region with stretching, because of the weakening of the intermolecular hydrogen bonding by increasing the interatomic distances. On the other hand, that of the parallel polarization shifts to a higher wavenumber region because of the shortening of the interatomic distance from α to β crystal form (the strength of the intramolecular hydrogen bonding became stronger) by stretching.

Long-Lasting In Vivo Effects of the Cannabinoid CB1 Antagonist AM6538.

AM6538 is a cannabinoid antagonist that binds CB1 receptors expressed in HEK-293 cells in a wash-resistant manner. The effects of AM6538 in live animals has not previously been established. We characterized the antagonist effects of AM6538 in male mice, using a warm-water tail-withdrawal assay, and in male squirrel monkeys trained to discriminate the CB1 agonist AM4054 from vehicle. The cannabinoid agonists WIN 55,212, Δ9-tetrahydrocannabinol (THC), and AM4054 all produced 100% maximum possible antinociceptive effects in mice following vehicle pretreatment. One-hour pretreatment with increasing doses of AM6538 (0.1-10 mg/kg) produced first rightward, then downward shifts of the agonist dose-effect functions. Rimonabant, 1-10 mg/kg, produced parallel rightward shifts of the AM4054 dose-effect functions, and baseline effects of AM4054 were nearly recovered within 24 hours following 10 mg/kg of rimonabant. In contrast, in mice treated with 10 mg/kg of AM6538, antagonism of THC or AM4054 lasted up to 7 days. AM6538 also antagonized the discriminative stimulus effects of AM4054 in squirrel monkeys in a dose-related manner, and the effects of 3.2 mg/kg of AM6538 endured for more than 7 days. The effective reduction in CB1 receptor reserve was used to calculate the relative efficacy (tau values) of WIN 55,212, THC, and AM4054 in mice and of AM4054 monkeys, with results indicating that THC has a lower efficacy than WIN 55,212 or AM4054 in mice. These results demonstrate that AM6538 is a long-acting CB antagonist in vivo, and further suggest that differences in CB efficacy can be revealed in behavioral assays following AM6538 treatment.

Convergent selection pressures drive the evolution of rhodopsin kinetics at high altitudes via nonparallel mechanisms.

Convergent evolution in response to similar selective pressures is a well-known phenomenon in evolutionary biology. Less well understood is how selection drives convergence in protein function, and the underlying mechanisms by which this can be achieved. Here, we investigate functional convergence in the visual system of two distantly related lineages of high-altitude adapted Andean and Himalayan catfishes. Statistical analyses revealed in the two high-altitude lineages, a parallel acceleration of evolutionary rates in rhodopsin, the dim-light visual pigment. However, the elevated rates were found to be accompanied by substitutions at different sites in the protein. Experiments substituting Andean- or Himalayan-specific residues significantly accelerated the kinetic rates of rhodopsin, destabilizing the ligand-bound forms. As found in cold-adapted enzymes, this phenotype likely compensates for a cold-induced decrease in kinetic rates, properties of rhodopsin mediating rod sensitivity and visual performance. Our study suggests that molecular convergence in protein function can be driven by parallel shifts in evolutionary rates but via nonparallel molecular mechanisms. Signatures of natural selection may therefore be a powerful guide for identifying complex instances of functional convergence across a wider range of protein systems.

Possible antagonistic effects of the TRPC4 channel blocker ML204 on M2 and M3 muscarinic receptors in mouse ileal and detrusor smooth muscles and atrial myocardium.

ML204, a potent transient receptor potential canonical 4 (TRPC4) channel blocker, is often used to elucidate the involvement of TRPC4 channels in receptor-operated signaling processes in visceral smooth muscles. In the present study, we investigated the possible antagonistic actions of ML204 on M2 and M3 muscarinic receptors, which mediate contractions in mouse ileal and detrusor smooth muscles. In ileal and detrusor smooth muscle preparations, ML204 (3 or 10 µM) significantly inhibited electrical field stimulation (EFS)-evoked cholinergic contractions. However, it did not significantly inhibit high K+-induced and EFS-evoked non-cholinergic contractions in the ileal preparations. When the muscarinic agonist, carbachol was cumulatively applied, ML204 (1, 3 and 10 µM) caused a rightward parallel shift of the concentration-response curves of carbachol. Additionally, ML204 (1, 3 and 10 µM) inhibited carbachol-induced negative chronotropic response in atrial preparations, which is mediated by M2 muscarinic receptors. Furthermore, ML204 significantly inhibited the contractions evoked by carbachol-induced intracellular Ca2+ release, which is mediated by M3 muscarinic receptors. These results suggested that ML204 might exhibit antagonistic actions on M2 and M3 muscarinic receptors; in addition, the inhibitory effects of ML204 against EFS-induced cholinergic contractions might be attributed to this receptor antagonism rather than inhibition of TRPC4 channel activity. Therefore, these effects should be considered when ML204 is used as a TRPC4 channel blocker.

Gaze-Cueing With Crossed Eyes: Asymmetry Between Nasal and Temporal Shifts.

A person's direction of gaze (and visual attention) can be inferred from the direction of the parallel shift of the eyes. However, the direction of gaze is ambiguous when there is a misalignment between the eyes. The use of schematic drawings of faces in a previous study demonstrated that gaze-cueing was equally effective, even when one eye looked straight and the other eye was averted. In the current study, we used more realistic computer-generated face models to re-examine if the diverging direction of the eyes affected gaze-cueing. The condition where one eye was averted nasally while the other looked straight produced a significantly smaller gaze-cueing effect in comparison with when both eyes were averted in parallel or one eye was averted temporally. The difference in the gaze-cueing effect disappeared when the position of one eye was occluded with a rectangular surface or an eye-patch. These results highlight the possibility that the gaze-cueing effect might be weakened when a direct gaze exists between the cueing eye (i.e., nasally oriented eye) and the target and the effect magnitude might depend on which type of face stimulus are used as a cue.

Parallel Voice Onset Time shift in Chinese Korean

Abstract This study reveals the existence of a Voice Onset Time shift in the Korean spoken by native speakers residing in northeast China, a shift parallel to those reported in other Korean varieties in Korea, the USA, and Canada. The VOT pattern observed in the Chinese Korean community is argued to represent a change that cannot be simply explained in terms of diffusion via recent dialect contact, or as a feature directly inherited from the source language when it was transplanted into China over a century ago. We suggest that behind the parallel VOT shifts is the power of “drift” that drives the different Korean varieties along similar journeys of language evolution. This study presents an intriguing case where internal changes driven by “drift” may actually be initiated and further supported by language/dialect contact.

Fire-induced forest transition to derived savannas: Cascading effects on ant communities

Changes in land-use and climate increase the flammability of forests across southeast Amazonia, potentially driving abrupt fire-mediated transitions to derived savannas – grass-dominated degraded forests with scattered trees. However, the extent to which the forest fauna undergoes a parallel process remains poorly understood. Here we test the hypothesis that the process of fire-driven forest shifts towards derived savannas has congruent cascading effects on ant communities by causing declines in forest specialists and an influx of open-habitat taxa. In 2013 we collected ants using subterranean, epigaeic and arboreal pitfall traps in three adjacent 50-ha plots: an unburnt control and two treatment plots that were burnt either triennially or annually from 2004 to 2010. Frequent fire was associated with a marked decline of specialist forest species (almost 50%), and an influx of open-habitat taxa that were absent from the unburnt plot. The effects were particularly pronounced for epigaeic ants: their abundance, biomass, species richness and species composition were impacted by fires, and this was the main stratum occupied by the open-habitat species. Previous studies have shown that a similar conversion is not triggered by single fires, and they therefore require recurrent fires. Our results provide experimental evidence that the process of tropical forest conversion towards derived savannas caused by repeated burning is a broad one that affects not only plants, but involves parallel compositional shifts of animal communities. The prevention of recurrent fires is a priority challenge for avoiding widespread biotic conversion of tropical forests to derived savannas.

Oxygen Interstitial Creation in a-IGZO Thin-Film Transistors Under Positive Gate-Bias Stress

The electrical recovery behaviors of the amorphous InGaZnO thin-film transistors (a-IGZO TFTs) after positive gate-bias stress (PBS) are investigated. The TFTs show an evident sub-threshold swing (SS) degradation after the PBS removal when the channel layer is deposited at relatively high oxygen flow rates, although they exhibit a parallel positive shift in the transfer characteristics during the PBS. It is inferred that the SS degradation results from the oxygen interstitial defects created in the a-IGZO channel during the PBS, which are in the octahedral configuration and are usually more easily created in the oxygen-rich a-IGZO channel layer. They are electrically inactive during the PBS due to the “negative U” behavior and then become relaxed and electrically active during the recovery process, leading to the SS degradation during the recovery process.