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Alternative reproductive tactics (ARTs) allow less competitive individuals to reproduce by avoiding direct fights through sneaky strategies. Within cooperatively breeding groups ARTs are rarely reported, potentially owing to observational difficulties or reproductive suppression by group members. In societies where mating opportunities cannot be monopolized by one male, young males could use sneaky tactics as an intermediate 'stepping-stone' tactic to gain limited reproductive success while growing in resource-holding potential (RHP). Using decades of pedigree, weight, group demography and behavioural data, we investigated the use of sneaky 'sneaker' ARTs in wild male banded mongooses. In this species, groups typically contain more adult males than breeding females, leading to intense male-male competition. Instead of as a stepping-stone, sneaking tactics were typically used by males who had been displaced from mate-guarding status by stronger rivals. Additionally, sneakers had lower siring success compared with mate guards, despite similar weight loss costs, which may explain why males typically avoided reproductive activity entirely rather than sneaking. However, young sneakers gain access to older, higher fecundity females in the group and sneaking may even facilitate inbreeding avoidance. Overall, ARTs in stable social groups can predictively emerge from changes in relative RHP and social status over the lifetime.

This contribution is a comment on a simulation study of Robert J. Knell and Jonathan M. Parrett (Evo. Lett. 8, 539-349, 2024). There is growing evidence that in ecological adaptation, sexual selection is a "double-edged sword"-it can fuel adaptation and population persistence, or hinder adaptation and lead to population extinction. Knell and Parrett explore this topic, using an individual-based model to investigate how alternative reproductive tactics (ARTs) affect adaptation to changing environments. They find that in the presence of ARTs, extinction can be averted, as fixed ARTs facilitate evolutionary rescue. While we appreciate their research question and approach, we question the generality of this result. First, some of their conclusions hinge on the parameter values chosen. In their model, individuals express one of two reproductive tactics (fighting or sneaking) depending on whether their condition exceeds a given threshold. We demonstrate that their conclusions rely strongly on this threshold value. For high values (i.e., when most individuals sneak), they observe evolutionary rescue-however, for values lower than those explored in K&P, fixed ARTs do not impact extinction. When we allow the threshold to evolve, it evolves to take low values, indicating that when fixed ARTs are adaptive, they do not promote evolutionary rescue. Second, K&P assume that the sneaking strategy results in considerably lower mating success than the fighting strategy. We show that, if the average mating success of the sneaking strategy is increased, fixed ARTs again do not cause evolutionary rescue. Finally, we show that varying the degree of influx of variation or the inheritance process similarly breaks the association between fixed ARTs and evolutionary rescue. Overall, we agree with K&P that ARTs may influence evolutionary rescue, but possibly in different contexts than those considered in their manuscript. Thus, whether and how ARTs shape extinction risk remains an open question.

Sexual selection has strong effects on gonad size, which has been proposed to shift energetic allocations, resulting in concomitant decreases in brain size. However, mixed findings leave it unclear whether negative correlations reflect direct energetic trade-offs or selection on trait combinations broadly. We tested whether male reproductive tactics impose energetic trade-offs by comparing brain and gonad sizes in Poecilia parae, a fish with discrete alternative male morphs specializing in three reproductive strategies: coercion, display, and sneaking. The obligate sneaker morph had substantially larger gonads and smaller brains than the other morphs, consistent with an energetic trade-off. However, examining individuals within morphs revealed a positive relationship, contradicting the energetic trade-off hypothesis. To resolve which morphs reflect the ancestral tissue state, we also compared gonad and brain sizes of the morphs to two closely related species whose males utilize more flexible reproductive strategies, Poecilia picta and Poecilia reticulata. Again, the P. parae obligate sneaker morph had the largest gonads and the smallest brains. Neuron-to-glia ratio (a proxy for energetic demands) showed no link to gonad size. Our results suggest that reproductive strategies shape brain evolution through correlational selection rather than direct energetic trade-offs, challenging assumptions that sexually selected traits impose constraints through direct resource allocation.

Neuromorphic in-memory computing has emerged as one of the forerunners in addressing the data deluge problem in this age of smart electronics and artificial intelligence. Memristor crossbar arrays are fundamental storage and processing hardware frameworks that enable in-memory computing. Halide perovskites have been examined for memristors, owing to their mixed ionic-electronic conduction and solution processability. However, such studies so far have not addressed the challenge of sneak paths, which can result in erroneous computation. Self-rectifying memristors, which can be integrated into a passive crossbar array, are the most efficient solution to the sneak-path problem in terms of circuit complexity and device footprint. This work introduces a new approach to realizing a self-rectifying halide memristor by creating a 2D to 3D dimensionally graded perovskite. Through a careful selection of 2D spacer cations based on the energy level alignment with methylammonium lead iodide, a favorable heterojunction is created that achieves a rectification ratio > 103. Moreover, the memristor displayed robust synaptic characterization (endurance > 4 × 104 pulses) with high linearity in weight update. By suppressing the sneak currents, a far larger 140 × 140 crossbar array could be supported. Using this, 93% accuracy is achieved in an image classification task despite introducing write noise.

Ryan is a 6-year-old boy with a history of eosinophilic esophagitis (EoE) and poor weight gain referred to developmental-behavioral pediatrics (DBP) for attention-deficit/hyperactivity disorder (ADHD) and oppositional defiant disorder (ODD). Ryan's mother was concerned about Ryan's defiance and daily emotional outbursts, which could last up to an hour. Ryan's teachers frequently contacted the family due to disruptive behavior, impulsivity, and sneaking food.Ryan was born prematurely at 28 weeks and required nasogastric feeds for 1 month in the NICU. He has a history of reflux requiring proton pump inhibitors and failure to thrive at age 2 (currently at 6% for BMI). At age 4, he was evaluated by pediatric gastroenterology and subsequently diagnosed with EoE. Complete elimination of dairy, wheat, soy, eggs, nuts, and seafood/shellfish was recommended as per standard of care for EoE. The diet was difficult for the family and Ryan to maintain, and Ryan often had tantrums around foods/snacks. He would sneak into the pantry to eat things he was not supposed to, causing significant parent-child conflict. Food restrictions were particularly challenging at school. Ryan would ask classmates for their cheese sticks and cookies; snacks he was not allowed to eat. Despite a 504 plan in place, his teachers were unable to monitor his intake.Parent and teacher behavior rating scales were consistent with ADHD-combined type and ODD. Cognitive and academic testing demonstrated academic underachievement in math and reading; however, these results were thought to be an underrepresentation of his true abilities due to easy distractibility and impulsivity observed during assessments. Behavioral therapy, IEP evaluation, and trial of ADHD medication were recommended.Given his poor weight gain and inability to swallow tablets, a nonstimulant, guanfacine immediate release (IR) was initiated. Guanfacine was helpful, but titration was limited due to daytime sedation. Ryan was placed on homebound services due to frequent EoE flares and concerns that school could not adequately monitor food restrictions.GI recommended elemental formula as his primary source of intake due to nonadherence to diet. Ryan required a gastrostomy tube (g-tube) due to his refusal to drink elemental formula. Although EoE symptoms improved, Ryan had increased oppositional and defiant behaviors with his homebound teacher and parents. An extended-release oral liquid methylphenidate stimulant was started in conjunction with guanfacine and resulted in significant improvement of ADHD symptoms. Ryan experienced weight loss and decreased BMI to 3%. Periactin was initiated to help with appetite and sleep quality.After 3 months, Ryan started feeding therapy and behavioral therapy with a family component. He was also approved for home nursing support and respite hours. Several months later, Ryan endorsed missing his friends and wanting to go back to school. He agreed to sign a behavioral contract stating that if he returned to school, he would not sneak/steal food.What are some recommendations to consider for addressing Ryan's behavioral challenges?

hIAPP (human islet amyloid polypeptide) aggregates have been implicated in the development of type 2 diabetes mellitus (T2DM). As a prelude to developing a potential cure for T2DM, researchers worldwide have employed various strategic molecular entities to target β-sheet-rich hIAPP aggregates, known as disruptors, or to prevent the self-assembly of hIAPP, known as inhibitors. Peptide-based strategies are at the forefront. Most β-sheet breakers have a pre-installed breaker element, notably proline. Here, we describe a different approach that works in a pro-drug fashion-the use of the infamous aspartimide formation. The designed smart peptides sneak into the aggregating system as standard peptides and undergo various aspartimide-induced chemical transformations, developing into an anti-amyloidogenic agent. The peptide develops a pre-programmed kink via aspartimide formation. The kink misaligns the β-sheet topology of the hIAPP aggregates, significantly disrupting them. The reaction cascade is followed by racemization and nucleophilic ring opening by water, resulting in the formation of L-α/β and D-α/β aspartyl peptides. The L-peptides and D-isopeptides are anti-amyloidogenic. Moreover, the negative charges on such peptidomimetics improve solubility and recognisability. The strategy could be a promising leap toward developing therapeutics for amyloidogenic type 2 diabetes mellitus (T2DM). This study will also help to understand the aggregation-disaggregation mechanism of hIAPP.

Conventional sex roles imply that males compete more vigorously with each other for fertilizations, whereas females are more selective in choosing a mate. As a consequence, mating and reproductive success is typically more variable in males (Bateman's principles). However, Charles Darwin already mused that some species may defy these principles, resulting in stronger sexual selection in females than males, but empirical evidence has been mixed. We studied the potential for sexual selection in two sympatric coucals-a bird family with high sex-role variability. In sex-role-reversed black coucals, females compete for territories while males provide parental care. In white-browed coucals, sex roles are flexible. Females of both species had steeper Bateman gradients than males, suggesting females benefit from multiple mating. Male black coucals benefitted from sneaking copulations with their social mate while she prepared clutches for other mates-a male strategy not conceptually included in Bateman's principles that focuses on the number of mating partners, but not on increasing reproductive success by repeatedly mating with the same partner. Our findings support reversed Bateman's principles, with females having a higher potential for sexual selection than males. Sex-role flexibility allows females to secure additional mates and emancipate themselves from parental care, and it allows males to invest in parental care and emancipate themselves from pre-copulatory competition.

Artificial optoelectric synapses that integrate dual functions of memristor and a selector hold significant practical potential for developing next-generation high-density neuromorphic computing systems. Herein, an optoelectronic synaptic memristor based on ZnS is proposed, enabling reversible switching between long-time stable (>104 s) nonvolatile bipolar resistive switching characteristics (on/off ratio >105) and a tunable volatile self-rectifying mode (rectification ratio ranging in 45-104), thus functioning as integrated selector and memristor. The device realizes multilevel memory and effectively emulates diverse biological synaptic plasticity behaviors under electrical or near-infrared (808 and 980 nm) light stimulation, while also reproducing the brain-like Ebbinghaus "learning-forgetting-consolidation" rules. This work holds scientific significance for advancing the potential of devices with self-suppressing sneak current functionality in brain-inspired neuromorphic computing systems.

The advancement of neuromorphic computing hardware requires energy-efficient operation, scalable device integration, and reliable conduction. These challenges can be effectively addressed by employing functional ferroelectric material as an active layer in memristors, leveraging their electrostatically modulated conduction for reliable switching. In this study, we present memristor devices that achieve a rectifying ratio exceeding 10⁶ and an off-state current below 10⁻¹² A based on epitaxial heterostructures consisting of Pt/Ba0.2Bi0.8FeO3 (BBFO)/SrRuO3/SrTiO3 stacks. Substitution of 20% Ba in BiFeO₃ induces a coupled interaction between ferroelectric polarization and oxygen vacancy migration, which under pulsed bias governs vacancy transport and ensures reliable memristive synaptic behavior with near-zero nonlinearity and endurance beyond 10⁷ cycles. Owing to the demonstrated linear synaptic performance and strong memristive rectification, a selector-free crossbar array (CBA) was implemented. By mitigating key CBA challenges such as sneak currents and cell-to-cell variability while maintaining high synaptic performance, BBFO provides a robust material platform for CBA-based neuromorphic systems.

Recent integration of 3D memory technologies such as high-bandwidth memory [HBM] into AI accelerators has enhanced neural network performance. However, the stacked structures of 3D memories result in notable heat accumulation because lateral interfaces obstruct vertical heat dissipation, thereby hindering effective cooling. An effective approach to mitigating energy consumption involves the utilization of nonvolatile memory technologies, such as resistive random-access memory (RRAM). Integration of selector transistors with RRAM devices mitigates sneak path leakage, increases nonlinearity, and improves the reliability of vertically stacked arrays. Nevertheless, executing core AI tasks-such as vector-matrix multiplication in neuromorphic computing-requires substantial current flow through these transistors, which in turn leads to heat generation, reduced power efficiency, and potential computational errors. Additionally, densely stacked layers create hotspots and restrict access to cooling interfaces. This study presents a comparative analysis of models with various selector transistor configurations, based on power parameters from microfabricated 3D RRAM structures. The results indicate that optimally positioning the selector transistor at the memory interface can reduce nanoscale heat accumulation by up to 11%, as verified through finite-element simulations and numerical calculations. Improved thermal management reduced peak local temperatures from over 160 °C to below 60 °C within 20 nanoseconds in configurations featuring 10 to 100 stacked layers.

By integrating rectification and resistive switching functionalities, self-rectifying memristors play a pivotal role for large-scale, high-density 3D integration, which can effectively suppress sneak-path currents. However, the limited reliability and poor overall performance of mainstream metal oxide-based self-rectifying memristors hinder their widespread practical application. Herein, robust self-rectifying memristors are fabricated using an amorphous WO3/amorphous IGZO (a-WO3/a-IGZO) heterostructure, and they exhibit excellent high-performance characteristics, including a high rectification ratio (>104), low operating voltages, and outstanding operational stability. This enhanced self-rectifying switching performance is attributed to the formation of an interfacial space-charge layer, resulting from the mismatch in carrier concentration between a-WO3 and a-IGZO. Furthermore, multisynaptic functions are subsequently emulated using a-WO3/a-IGZO heterostructure memristors, whose conductance can be continuously modulated. This work presents a heterostructure strategy for constructing robust, high-performance self-rectifying memristors based on amorphous metal oxides, which effectively suppress crosstalk currents and serve as reliable artificial synapses for neuromorphic computing.

The deceleration of Moore's law and the energy-latency drawbacks of the von Neumann bottleneck have heightened the pursuit for beyond‑CMOS designs that integrate memory and compute. Self‑rectifying memristors (SRMs) have emerged as promising building blocks for high‑performance, low‑power systems by combining resistive switching with intrinsic diode-like behavior. Their unidirectional conduction inhibits sneak‑path currents in crossbar arrays devoid of external selectors, while nonlinear I-V characteristics, adjustable conductance states, low operating voltages, and rapid switching facilitate efficient vector-matrix operations, neuromorphic plasticity, and hardware security primitives. This review synthesizes the working mechanisms of SRMs, surveys material, and structural strategies and compares device metrics relevant to array‑scale deployment (rectification ratio, nonlinearity, endurance, retention, variability, and operating voltage). We assess SRM-enabled in-memory computing and neuromorphic applications, as well as security functions such as physical unclonable functions and reconfigurable cryptographic primitives. Integration pathways toward CMOS compatibility are analyzed, including back-end-of-line thermal budgets, uniformity, write disturb mitigation, and reliability. Finally, we outline key challenges and opportunities: materials/architecture co‑design, precision analog training, stochasticity control/exploitation, 3D stacking, and standardized benchmarking that can accelerate large‑scale SRM adoption. Through the use of specialized materials and structural optimization, SRMs are set to provide selector‑free, densely integrated, and energy‑efficient hardware for future information processing.

Female mimicry is a reproductive tactic typically employed by small males (minors) in species with female- or resource-defense polygyny. By mimicking females, minors may secure copulations without being detected by territorial males (majors). We used three complementary approaches to investigate the possibility of female mimicry in the male-dimorphic harvestman Serracutisoma proximum, a chemically-oriented arachnid with a resource-defense mating system. Minors rely primarily on sneak copulations, and if they exhibit female mimicry, we expect them to elicit behavioral responses from majors similar to those directed toward females. Indeed, a field experiment showed that majors displayed reduced aggression toward minors and even attempted copulation with some of them. To examine the mechanisms underlying of mistaken sex identification, we compared the cuticular chemical profiles of majors, minors, and females, and quantified the density of chemoreceptors on the sensory legs of majors and minors. Contrary to female mimicry predictions, the overall chemical profile of minors did not resemble that of females. However, some compounds that signal female reproductive status in spiders showed similar abundances in minors and females. Additionally, chemoreceptor density did not differ between majors and minors, suggesting that mistaken sex identification is also not due to sensory limitations in majors. In conclusion, while behavioral evidence is consistent with female mimicry, the underlying mechanisms remain unresolved. Regardless of the underlying mechanism, the ability of some minors to access and mate with females even in the presence of majors likely confers reproductive advantages, which could maintain alternative reproductive tactics within the population.