Opposite Direction Research Articles

The California current system off Baja California Sur

Based on hydrographic data from two cruises (June 2010 and May 2012) off Baja California Sur, Mexico, historical in situ measurements from the World Ocean Database 2018, California Cooperative Oceanic Fisheries Investigations, and Investigaciones Mexicanas de la Corriente de California cruise programs, as well as satellite images and data from the Global Reanalysis, this study describes the California Current System off Baja California Sur. The California Current System is characterized by the interaction of four near-surface currents. Far from the coast, the California Current flows within the North Pacific Subtropical Gyre but does not reach the Pacific Tropical-Subtropical Convergence off Mexico. From December to June, an equatorward flow known as the Tropical Branch of California Current emerges along the coast. This flow intensifies from March to June and is closely related to the mass flux induced by coastal upwelling. In July, a new branch of the Tropical Branch of the California Current turns poleward along the Baja California Sur coast. This flow is often referred to as the California Surface Countercurrent because it flows in the opposite direction to the California Current. Additionally, the California Undercurrent is detected, influencing the water column from 100 to 900 m, with a maximum poleward flow between 200 m and 300 m, decreasing toward the surface. The California Undercurrent persists throughout the year over the continental slope, displaying a significant semiannual component around the Gulf of California entrance. The California Current System off Baja California Sur plays a crucial role in the formation of Transitional Waters within the Pacific Tropical-Subtropical Convergence off Mexico. The importance of equatorward flows by the Tropical Branch of California Current in ventilating the Oxygen Minimum Zone waters in the Central Pacific off Mexico is emphasized.

Application of passive vortex generators to enhance vertical mixing in an open raceway pond

A novel use of vortex generators in a raceway pond is described here, with the flow field quantitatively simulated using computational fluid dynamics using the large eddy simulation turbulence model. Persistence lengths of the swirling motion generated by the vortex generators indicate that significant vertical mixing can be achieved by placing vortex generators in the straight section opposite the paddle wheel, downstream of the first hairpin bend. Relatively simple vortex generators are capable of creating stronger swirling motions that persist for a longer distance than those created by the paddle wheel. For optimal performance, vortex generators are positioned side by side but in opposite directions, and their diameters should be equal to or slightly less than the desired liquid depth. The optimal length of a 0.18 m diameter vortex generator in a 0.2 m deep pond was determined to be 0.3 m. Furthermore, it has been demonstrated that a longer persistence length is achieved by inducing a swirling motion with its rotational axis parallel to the primary flow direction.

Supermirrors and spin wave amplifications

Superradiance, a phenomenon of multiple facets, normally occurs in classical/quantum physics under extreme conditions. Here, we present its manifestation in spin waves under a practical condition. We show that an interface between a current-free ferromagnetic region and a current-flow ferromagnetic region can be a spin wave supermirror whose reflection coefficient is larger than 1. The super-reflection is the consequence of current-induced spectrum inversion where phase and group velocities of spin waves are in the opposite directions. An incident spin wave activates a backward propagating refractive wave inside the current-flow region. The refractive spin wave re-enters the current-free region to constructively interfere with the reflective wave. It appears that the current-flow region coherently emits reflective waves, leading to a super-reflection. The process resembles superradiance of a spinning black hole through the Hawking radiation process or Dicke superradiance of cavity photons inside population inverted media.

Balancing acts of kindness: Reassessing the relationship between informal helping and formal volunteering

Although time is a finite resource, much sociological research suggests a positive association between engagement in informal helping activities and formal volunteering. However, it remains unclear whether this relationship is causal and, if so, in which direction the causality runs. To address these issues, I draw on two-wave panel data from Denmark. Using a cross-lagged panel model, I find no evidence that formal volunteering hours affect informal helping activities. However, in the reverse direction, I find evidence of a right-skewed inverse U-shaped relationship. Specifically, the time individuals dedicate to formal volunteering marginally increases with time allocated to informal helping activities, but only as long as their informal helping obligations remain modest. However, once these informal helping obligations reach approximately 20 hours, the time individuals spend on formal volunteering decreases with informal helping hours. These findings suggest that even exceptionally helpful individuals, often referred to as “super-helpers,” must balance their acts of kindness and their available time and energy. Moreover, I argue that while many people are motivated to engage in formal volunteering to benefit others, those with family and friends requiring assistance tend to prioritize these responsibilities before volunteering.

Self-consistent quantum-kinetic theory for interacting drifting electrons and force-driven phonons in a 1D system

A self-consistent quantum-kinetic model is developed for studying strong-field nonlinear electron transport interacting with force-driven phonons within a nanowire system. For this model, phonons can be dragged into motion through strong electron–phonon scattering by fast-moving electrons along the opposite direction of the DC electric field. Meanwhile, the DC-field induced charge current of electrons can be either enhanced or reduced by the same electron–phonon scattering, depending on the relative direction of a DC field with respect to that of an applied temperature gradient for driving phonons. By making use of this quantum-kinetic model beyond the relaxation-time approximation, neither electron nor phonon temperature is required for describing ultrafast electron–phonon scattering and their correlated transports in this 1D electronic-lattice system.

Enhancing Electrode Performance through Triple Distribution Modulation of Active Material, Conductive Agent, and Porosity.

The increasing demand for large-scale energy storage propels the development of lithium-ion batteries with high energy and high power density. Low tortuosity electrodes with aligned straight channels have proved to be effective in building such batteries. However, manufacturing such low tortuosity electrodes in large scale remains extremely challenging. In contrast, high-performance electrodes with customized gradients of materials and porosity are possible to be made by industrial roll-to-roll coating process. Yet, the desired design of gradients combining materials and porosity is unclear for high-performance gradient electrodes. Here, triple gradient LiFePO4 electrodes (TGE) are fabricated featuring distribution modulation of active material, conductive agent, and porosity by combining suction filtration with the phase inversion method. The effects and mechanism of active material, conductive agent, and porosity distribution on electrode performance are analyzed by experiments. It is found that the electrode with a gradual increase of active material content from current collector to separator coupled with the distribution of conductive agent and porosity in the opposite direction, demonstrates the best rate capability, the fastest electrochemical reaction kinetics, and the highest utilization of active material. This work provides valuable insights into the design of gradient electrodes with high performance and high potential in application.

KCNH6 is essential for insulin secretion by regulating intracellular ER Ca2+ store.

Appropriate Ca2+ concentration in the endoplasmic reticulum (ER), modulating cytosolic Ca2+ signal, serves significant roles in physiological function of pancreatic β cells. To maintaining ER homeostasis, Ca2+ movement across the ER membrane is always accompanied by a simultaneous K+ flux in the opposite direction. KCNH6 was proven to modulate insulin secretion by controlling plasma membrane action potential duration and intracellular Ca2+ influx. Meanwhile, the specific function of KCNH6 in pancreatic β-cells remains unclear. In this study, we found that KCNH6 exhibited mainly ER localization and Kcnh6 β-cell-specific knockout (βKO) mice suffered from abnormal glucose tolerance and impaired insulin secretion in adulthood. ER Ca2+ store was overloaded in islets of βKO mice, which contributed to ER stress and ER stress-induced apoptosis in β cells. Next, we verified that ethanol treatment induced increases in ER Ca2+ store and apoptosis in pancreatic β cells, whereas adenovirus-mediated KCNH6 overexpression in islets attenuated ethanol-induced ER stress and apoptosis. In addition, tail-vein injections of KCNH6 lentivirus rescued KCNH6 expression in βKO mice, restored ER Ca2+ overload and attenuated ER stress in β cells, which further confirms that KCNH6 protects islets from ER stress and apoptosis. These data suggest that KCNH6 on the ER membrane may help to stabilize intracellular ER Ca2+ stores and protect β cells from ER stress and apoptosis. In conclusion, our study reveals the protective potential of KCNH6-targeting drugs in ER stress-induced diabetes.

Bursting Sand Balloons

Using linear elasticity theory, we describe the mechanical response of dry non-cohesive granular masses of Ottawa sand contained by spherical rubber balloons subject to sudden bursting in the earliest instants of the event. Due to the compression imposed by the balloon, the rupture produces a fast radial expansion of the sand front that depends on the initial radius R0, the initial pressure p originated by the balloon, and the effective modulus of compression Ke. The hydrostatic compression approximation allows for the theoretical study of this problem. We found a linear decompression wave that travels into the sand and that induces a radial expansion of the granular front in the opposite direction with similar behavior to the wave but with a slightly lower speed.

On the measurement of cause of death inequality.

Attempts at assessing heterogeneity in countries' mortality profiles often rely on measures of cause of death (CoD) diversity. Unfortunately, such indicators fail to take into consideration the degree of (dis)similarity among pairs of causes (e.g. 'transport injuries' and 'unintentional injuries' are implicitly assumed to be as dissimilar as 'transport injuries' and 'Alzheimer's disease')－an unrealistic and unduly restrictive assumption. We extend diversity indicators proposing a broader class of heterogeneity measures that are sensitive to the similarity between the causes of death one works with. The so-called 'CoD inequality' measures are defined as the average expected 'dissimilarity between any two causes of death'. A strength of the approach is that such measures are decomposable, so that users can assess the contribution of each cause to overall CoD heterogeneity levels-a useful property for the evaluation of public health policies. We have applied the method to 15 low-mortality countries between 1990 and 2019, using data from the Global Burden of Disease project. CoD inequality and CoD diversity generally increase over time across countries and sex, but with some exceptions. In several cases (notably, Finland), both indicators run in opposite directions. CoD inequality and diversity indicators capture complementary information about the heterogeneity of mortality profiles, so they should be analysed alongside other population health metrics, such as life expectancy and lifespan inequality.

Leveraging Tunable Nanoparticle Surface Functionalization to Alter Cellular Migration.

Gold nanoparticles (AuNPs) are a promising platform for biomedical applications including therapeutics, imaging, and drug delivery. While much of the literature surrounding the introduction of AuNPs into cellular systems focuses on uptake and cytotoxicity, less is understood about how AuNPs can indirectly affect cells via interactions with the extracellular environment. Previous work has shown that the monocytic cell line THP-1's ability to undergo chemotaxis in response to a gradient of monocyte chemoattractant protein 1 (MCP-1) was compromised by extracellular polysulfonated AuNPs, presumably by binding to MCP-1 with some preference over other proteins in the media. The hypothesis to be explored in this work is that the degree of sulfonation of the surface would therefore be correlated with the ability of AuNPs to interrupt chemotaxis. Highly sulfonated poly(styrenesulfonate)-coated AuNPs caused strong inhibition of THP-1 chemotaxis; by reducing the degree of sulfonation on the AuNP surface with copolymers [poly(styrenesulfonate-co-maleate) of different compositions], it was found that medium and low sulfonation levels caused weak to no inhibition, respectively. Small, rigid molecular sulfonate surfaces were relatively ineffective at chemotaxis inhibition. Unusually, free poly(styrenesulfonate) caused a dose-dependent reversal of THP-1 cell migration: at low concentrations, free poly(styrenesulfonate) significantly inhibited MCP-1-induced chemotaxis. However, at high concentrations, free poly(styrenesulfonate) acted as a chemorepellent, causing a reversal in the cell migration direction.

Wavelength-tunable quasi-unidirectional spatiotemporal mode-locked solitons in an isolator-free Er-doped fiber laser

In this letter, we have demonstrated the realization of the wavelength-tunable spatiotemporal mode-locked (STML) operation in an Er-doped partial multimode fiber laser without the intracavity isolator. The laser adopts an all-fiber structure and the saturable absorption effect is attributed to nonlinear multimode interference (NL-MMI) from the single mode fiber-graded index multimode fiber-single mode fiber (SMF-GIMF-SMF) design. The STML laser can operate in the quasi-unidirectional regime with an emission strength difference of larger than 30 dB for the two counter-propagating lasers. And the switching between the dominating operating directions in the clockwise (CW) or counter-clockwise (CCW) directions can be easily achieved by adjusting the MM polarization controller (PC). Both STML conventional solitons (CSs) and the STML soliton molecules are obtained with a similar tunable wavelength from ∼1.56 μm to ∼1.58 μm for the opposite operating directions. Furthermore, the spatial dynamics of the STML soliton are also investigated in detail. The experimental results are of great help for us to explore nonlinear spatiotemporal dynamics and provide potential applications in fields of all-optical signal processing, fiber sensing and information coding.

Kinetics of N- to M-Polar Switching in Ferroelectric Al1-xScxN Capacitors.

Ferroelectric wurtzite-type aluminum scandium nitride (Al1-xScxN) presents unique properties that can enhance the performance of non-volatile memory technologies. The realization of the full potential of Al1-xScxN requires a comprehensive understanding of the mechanism of polarization reversal and domain structure dynamics involved in the ferroelectric switching process. In this work, transient current integration measurements performed by a pulse switching method are combined with domain imaging by piezoresponse force microscopy (PFM) to investigate the kinetics of domain nucleation and wall motion during polarization reversal in Al0.85Sc0.15N capacitors. In the studied electric field range (from 4.4 to 5.6MVcm-1), ferroelectric switching proceeds via domain nucleation and wall movement. The currently available phenomenological models are shown to not fully capture all the details of the complex dynamics of polarization reversal in Al0.85Sc0.15N. PFM reveals a non-linear increase of both domain nucleation rate and lateral wall velocity during the switching process, as well as the dependency of the domain pattern on the polarization reversal direction. A continuously faster N- to M-polar switching upon cycling is reported and ascribed to an increasing number of M-polar nucleation sites and density of domain walls.

Experimental and Numerical Investigation of Cylindrical and Shaped Cooling Holes With Forward and Reverse Injection

The present work proposes a suitable injection hole configuration of cylinder and laidback fan-shaped with forward and reverse direction for film cooling of a gas turbine blades application, based on experimental and numerical analysis. The experimental study is conducted for cylindrical hole at blowing ratio (1), injection angle (35°), and density ratio (1.2). The numerical study is performed for a wide range of operating parameters such as blowing ratios on (1-3), density ratios (2.42), mainstream flow Reynolds number as 4000 based on the hydraulic diameter of wind tunnel channel and, injection angle (35°) with the effect of forward and reverse injection of laidback fan shaped. The present study reveals that the formation of kidney vortices mitigated for reverse-shaped holes (secondary air is injected such that its axial velocity component is in the reverse direction to that of the mainstream) results in higher cooling performance with respect to forward-shaped holes. The coolant coverage is likewise more consistent and higher in the lateral direction compared to the forward injection.

Interaction mechanism between cloud cavitation and micro vortex flows

Micro vortex generators (micro-VGs) could affect cavitation, but the control mechanism is not yet fully understood. Simulating and analyzing the effect of micro vortex generators (micro-VGs) on cloud cavitation is crucial as it can help in suppressing the collapse of cavitation clouds, which is beneficial for marine machinery. In this work, micro-VGs were installed parallel to the initiation of the attached cavity on a NACA0015 hydrofoil. A compressible simulation method was used to obtain the cavitating flows around both the smooth hydrofoil and the one with micro-VGs. Subsequently, the generation of micro vortex flows and the effect of micro-VGs on transient evolution of cloud cavitation were analyzed. The results indicate that the installation of triangular micro vortex generators alters the flow vectors around them, inducing micro vortex flows with opposite rotational directions behind adjacent vortex generators. These vortex generators potentially affect cavitation on the hydrofoil by modifying pressure distribution, vortex structures, and turbulent kinetic energy. Under the specified cloud cavitation operating condition, the shedding and collapse of clouds on the smooth hydrofoil are replaced by the partial separation and collapse of sheet cavitation on the hydrofoil with micro-VGs. Despite a minor loss in time-averaged lift, the lift-to-drag ratio is improved, and the stability of the flow field is enhanced. After installing micro-VGs, the pressure fluctuation is primarily caused by the partial collapse and separation of sheet cavitation. Installing micro VGs at the hydrofoil's leading edge suppresses pressure pulsation.

Numerical study on the electromagnetic characteristics of multi-layer CORC cables

Due to the high isotropy and low AC losses, the multi-layer conductor on round core (CORC) cable is a good candidate for high field magnets, such as central solenoid magnets in fusion. Considering the difficulty in experimental measurement, numerical model is an effective way to illustrate the electromagnetic characteristics of the multi-layer CORC cable and provide further insights into its working performance. In this work, a 3D finite element model based on H formulation is proposed to simulate a CORC cable with as many as 18 layers considering electromagnetic coupling. The validity of the model has been verified by experimental results. Based on the proposed model, the DC transport current distribution characteristics and charge-discharge loss characteristics of multi-layer CORC cables wound in the same and opposite winding directions are investigated respectively. This work can provide an important reference for the design of multi-layer CORC cables for high-current or high-field application.

Temporal relation between pubertal development and peer victimization in a prospective sample of US adolescents.

Peer victimization typically peaks in early adolescence, leading researchers to hypothesize that pubertal timing is a meaningful predictor of peer victimization. However, previous methodological approaches have limited our ability to parse out which puberty cues are associated with peer victimization because gonadal and adrenal puberty, two independent processes, have either been conflated or adrenal puberty timing has been ignored. In addition, previous research has overlooked the possibility of reverse causality-that peer victimization might drive pubertal timing, as it has been shown to do in non-human primates. To fill these gaps, we followed 265 adolescents (47% female) prospectively across three-time points (Mage : T1 = 9.6, T2 = 12.0, T3 = 14.4) and measured self-report peer victimization and self- and maternal-report of gonadal and adrenal pubertal development on the Pubertal Development Scale. Multilevel modeling revealed that females who were further along in adrenal puberty at age 9 were more likely to report peer victimization at age 12 (Cohen's d = 0.25, p = .005). The relation between gonadal puberty status and peer victimization was not significant for either sex. In terms of the reverse direction, the relation between early peer victimization and later pubertal development was not significant in either sex. Overall, our findings suggest that adrenal puberty status, but not gonadal puberty status, predicted peer victimization in females, highlighting the need to separate gonadal and adrenal pubertal processes in future studies.

Exploring FPGA Switch-Blocks without Explicitly Listing Connectivity Patterns

Increased lower metal resistance makes physical aspects of Field-Programmable Gate Array (FPGA) switch-blocks more relevant than before. The need to navigate a design space where each individual switch can have significant impact on the FPGA’s performance in turn makes automated switch-pattern exploration techniques increasingly appealing. However, most existing exploration techniques have a fundamental limitation—they use the CAD tools as a black box to evaluate the performance of explicitly listed switch-patterns. Given the time needed to route a modern circuit on a single architecture, the number of switch-patterns that can be explicitly tested quickly becomes negligible compared to the size of the design space. This article presents a technique that removes this fundamental limitation by making the entire design space visible to the router and letting it choose the switches to be added to the pattern, based on the requirements of the circuits being routed. The key to preventing the router from selecting arbitrary switches that would render the final pattern excessively large is to apply the same negotiation principle used by the router to remove congestion, just in the opposite direction, to make the signals reach a consensus on which switches are worthy of being included in the final switch-pattern.

EAPRAD: A MAC protocol for Enhancing Access Probability and Reducing Access Delay in VANETs

Vehicular Ad Hoc Networks (VANETs) present challenges in terms of access collision and merge collision, leading to increased access delay in end-to-end vehicle communication. How to address these issues remains an unsolved problem. In this paper, we propose EAPRAD (Enhancing Access Probability and Reducing Access Delay), a novel MAC (Media Access Control) protocol based on a Markov model. Our protocol defines the number of vehicle accessing time slot failures, with different failure states forming a partial Markov chain. The highest failure status vehicle is prioritized to access the time slot, effectively resolving the problem of indefinite time slot reservations during the back-off phase. Furthermore, after acquiring the time slot, vehicles may still experience package collision, particularly when vehicles traveling in opposite directions share the same frequency band. To address this, our protocol introduces a new MAC frame structure that partitions available frequency band resources based on distinct driving directions, eliminating merge collision in opposite directions. For vehicles traveling in the same direction, intermediate nodes are utilized to proactively anticipate and prevent package collision. To model the state transition of access collision probability and merge, we develop a Continuous Time Markov Chain (CTMC) analytical model. Simulation results demonstrate that EAPRAD reduces end-to-end delay and beacon lost rate (BLR), thereby improving overall network performance in VANETs.

Bidirectional biotic interchange between Taiwan Island and Mainland China via land bridges—A case study of Obeidia Walker (Geometridae, Lepidoptera)

AbstractBiotic exchanges between Taiwan and Mainland China have shaped the biodiversity and ecosystems of both regions. Exchanges from Mainland China to Taiwan have received more attention, mainly studied in terrestrial vertebrates, while the reverse direction and invertebrates have largely been overlooked. Here, we explore the dispersal events between these two regions based on the moths of three species groups of Obeidia, including Taiwan taxa and its relatives from mainland. We conducted mixed methods and analysis, including reconstructing a phylogenetic tree, estimating associated divergence times and inferring ancestral areas and source regions, to explore the phylogeographical structure and genetic pattern of three groups based on eight genes. Our results revealed a structure of three clades and every clade included at least one Taiwanese taxa and its closest relatives of mainland of China, and also served Taiwan as an important source region of two mainland taxa. Our study revealed various origin pattern and dispersal models on the basis of three species groups of Obeidia. Bi‐directional biotic exchange via a land bridge were found: four Taiwanese taxa originated from mainland, and two of them migrated back to mainland. Both eastern Himalayas and south China are important origin areas for Taiwan biota, and the dominant source region may need multiple insect cases to confirm. Our study also provided evidences for disjunct distribution from the perspective of insecta molecular phylogeny.

Effects of common artificial sweeteners at environmentally relevant concentrations on soil springtails and their gut microbiota

Artificial sweeteners (AS) are extensively utilized as sugar substitutes and have been recognized as emerging environmental contaminants. While the effect of AS on aquatic organisms has garnered recent attention, their effects on soil invertebrates and gut microbial communities remain unclear. To address this knowledge gap, we exposed springtails (Folsomia candida) to both single and combined treatments of four typical AS (sucralose [SUC], saccharin [SAC], cyclamate [CYC], and acesulfame [ACE]) at environmentally relevant concentrations of 0.01, 0.1 and 1 mg kg−1 in soil. Following the first-generational exposure, the reproduction of juveniles showed a significant increase under all the AS treatments of 0.1 mg kg−1. The transcriptomic analysis revealed significant enrichment of several Kyoto Encyclopedia of Gene and Genome pathways (e.g., glycolysis/gluconeogenesis, pentose and glucuronate interconversions, amino sugar, and nucleotide sugar metabolism, ribosome, and lysosome) in springtails under all AS treatments. Analysis of gut bacterial microbiota indicated that three AS (SUC, CYC, and ACE) significantly decreased alpha diversity, and all AS treatments increased the abundance of the genus Achromobacter. After the sixth-generational exposure to CYC, weight increased, but reproduction was inhibited. The pathways that changed significantly (e.g., extracellular matrix-receptor interaction, amino sugar and nucleotide sugar metabolism, lysosome) were generally similar to those altered in first-generational exposure, but with opposite regulation directions. Furthermore, the effect on the alpha diversity of gut microbiota was contrary to that after first-generational exposure, and more noticeable disturbances in microbiota composition were observed. These findings underscore the ecological risk of AS in soils and improve our understanding of the toxicity effects of AS on living organisms.