Fin Extension Research Articles

Anatomical insights into fish terrestrial locomotion: A study of barred mudskipper (Periophthalmus argentilineatus) fins based on μCT 3D reconstructions.

Mudskippers are a group of extant ray-finned fishes with an amphibious lifestyle and serve as exemplars for understanding the evolution of amphibious capabilities in teleosts. A comprehensive anatomical profile of both the soft and hard tissues within their propulsive fins is essential for advancing our understanding of terrestrial locomotor adaptations in fish. Despite the ecological significance of mudskippers, detailed data on their musculoskeletal anatomy remains limited. In the present research, we utilized contrast-enhanced high-resolution microcomputed tomography (μCT) imaging to investigate the barred mudskipper, Periophthalmus argentilineatus. This technique enabled detailed reconstruction and quantification of the morphological details of the pectoral, pelvic, and caudal fins of this terrestrial mudskipper, facilitating comparison with its aquatic relatives. Our findings reveal that P. argentilineatus has undergone complex musculoskeletal adaptations for terrestrial movement, including an increase in muscle complexity and muscle volume, as well as the development of specialized structures like aponeuroses for pectoral fin extension. Skeletal modifications are also evident, with features such as a reinforced shoulder-pelvic joint and thickened fin rays. These evolutionary modifications suggest biomechanically advanced fins capable of overcoming the gravitational challenges of terrestrial habitats, indicating a strong selective advantage for these features in land-based environments. The unique musculoskeletal modifications in the fins of mudskippers like P. argentilineatus, compared with their aquatic counterparts, mark a critical evolutionary shift toward terrestrial adaptations. This study not only sheds light on the specific anatomical changes facilitating this transition but also offers broader insights into the early evolutionary mechanisms of terrestrial locomotion, potentially mirroring the transformative journey from aquatic to terrestrial life in the lineage leading to tetrapods.

Kinematics and muscle activity of pectoral fins in rainbow trout (Oncorhynchus mykiss) station holding in turbulent flow.

Pectoral fins play a crucial role in fish locomotion. Despite fishes living in complex fluid environments that exist in rivers and tidal flows, the role of the pectoral fins in navigating turbulent flows is not well understood. This study investigated the kinematics and muscle activity of pectoral fins in rainbow trout as they held station in the unsteady flows behind a D-section cylinder. We observed two distinct pectoral fin behaviors, one during braking and the other during Kármán gaiting. These behaviors were correlated to whole-body movements in response to the hydrodynamic conditions of specific regions in the cylinder wake. Sustained fin extensions during braking, where the fin was held out to maintain its position away from the body and against the flow, were associated with the cessation of forward body velocity, where the fish avoided the suction region directly downstream of the cylinder. Transient fin extensions and retractions during Kármán gaiting controlled body movements in the cross-stream direction. These two fin behaviors had different patterns of muscle activity. All braking events required recruitment from both the abductor and adductor musculature to actively extend a pectoral fin. In contrast, over 50% of fin extension movements during Kármán gaiting proceed in the absence of muscle activity. We reveal that in unsteady fluid environments, pectoral fin movements are the result of a complex combination of passive and active mechanisms that deviate substantially from canonical labriform locomotion, the implications of which await further work on the integration of sensory and motor systems.

Response and behavior of three spot gourami (<em>Trichopodus tricopterus</em> Pallas, 1770) on fields and electric currents during the fishing process

This research was conducted to explore how fish react and behave when exposed to electric currents during fishing. A total of 160 adult three spot gourami (T. trichopterus) were examined, each measuring approximately 9.75±0.44 cm in total length. The study was performed in a circular tank 180 cm in diameter and 80 cm in height. A Yuasa NS YTZ5S 12-volt, 5 Ah battery served as the electricity source. Fish behavior was monitored using a high-definition video camera capable of capturing 1080 × 60 fps. The findings revealed that at a distance of 30 cm from the electrodes and within 2.35 seconds, the fish exhibited increased swimming speed; signs of distress, fin extension, mild fainting, and tension; a slightly bent body and dorsal fin; and gill valve movement. After 4.15 seconds, the fish exhibited a loss of balance, mouth protrusion, increased fin activity, and a decreased response to external stimuli. Between 5.80 and 8.25 seconds, the fish completely lost balance, became rigid and unresponsive, and exhibited minimal, weak movements. At 20 cm from the electrode, the fish showed signs of anxiety and fainted within 8.10 seconds. At 28.35 seconds, there was partial loss of balance, and between 36.25 and 44.44 seconds, a total loss of balance and near-fainting occurred. However, at 40 cm from the electrode, the fish showed no response due to the extremely weak electric current (0.00–0.91 Ah).

Effects evaluation of Fin layouts and configurations on discharging performance of double-pipe thermochemical energy storage reactor

Thermochemical energy storage (TCES) based on hydrated salts is gaining popularity because it can provide high storage capacity at low costs. It is critical to improving heat storage efficiency and capacity due to technical challenges such as low thermal conductivity of thermochemical materials (TCMs) and poor mass transfer. The reversible reaction of strontium bromide monohydrate (SrBr2·H2O) and water vapor forming strontium bromide hexahydrate (SrBr2·6H2O) for TCES is used in numerical simulation, aiming to investigate the discharging performance of a double-pipe closed TCES reactor considering the influences of fin layouts (radial and longitudinal fins) by evaluating several indicators such as the reaction time and outlet temperature. The results show that the use of fins can improve the exothermic process. The discharging time of the reactor with upward L-shaped fins is reduced by 8.6% for radial fins and by 8.9% for the reactor with four longitudinal fins. The addition of fins expands the heat transfer area and makes the hydration rate of TCM around fins significantly higher than other parts. The Taguchi method is adopted to optimize the structure parameters of case 7 as it has the highest heat transfer amount of heat transfer fluid (HTF), and the optimal combination (A (fin number) = 4, B (fin extension length) = 20 mm, C (fin thickness) = 2 mm) increases the peak value of average outlet temperature by 1.47% and the heat exchange efficiency by 4.7% compared with case 7.

Numerical study on melting process and heat transfer analysis of a multitube combination latent heat storage unit with innovative harpoon-type fins

The heat transfer rate of a coupled system combining a passive residual heat removal system and a latent heat thermal energy storage system is directly related to worker safety in nuclear power plants. To enhance the heat transfer performance of the coupled system, in this study, the melting process of phase change material in the latent heat thermal energy storage system is numerically investigated by inserting innovative harpoon-type fins. A new assessment index is also proposed to evaluate the comprehensive heat transfer performance of fins. More than thirty cases with different harpoon-type fins are designed, and the impacts of various efficient structural parameters of the harpoon-type fin on the melting process are evaluate. The response surface method is used to optimize the structure. The results demonstrated that the handle length and the number of fins significantly improve the heat transfer performance of the harpoon-type fin. The optimal geometrical parameters (arc angle θ = 45°, handle length Lha = 10 mm, fin number Nf = 8, and arc number Na = 1) of harpoon-type fins are obtained. The heat transfer rate of the optimal fin structure is six times that without fins, and the total melting time is shortened by 85.9%. Furthermore, the longitudinal extension of the fins is more important than the complex horizontal extension of fins. The harpoon-type fin not only shows better performance in the coupled system but can also be used in shell-and-tube latent heat thermal energy storage systems.

Observations of Agonistic Behavior between Two Male Gobies Acentrogobius virgatulus (Jordan & Snyder, 1901), in Maizuru Bay, Kyoto Prefecture, Japan

Acentrogobius virgatulus (Jordan & Snyder, 1901) is a small coastal species of goby found along the Western Pacific. It is commonly found in Maizuru bay along the muddy sediment between the intertidal zone and depths of 10 m. In June and July of 2022, two independent agonistic interactions between male A. virgatulus were observed and recorded during its spawning season. One interaction, lasting over 4 minutes, included certain aggressive behaviors such as jaw locking, mouth gaping, fin extensions, rapid color changes, and fast strikes to the head and body. Another interaction exhibited similar mouth gaping, fin extension, and rapid color changes but did not lead to further escalation. These behaviors coincide with those found in similar species and provides in situ evidence of these uncommon interactions. This is the first record of agonistic behavior by an Acentrogobius species. Accumulating findings such as these can contextualize intraspecific interactions, reveal differences across multiple species, and guide future experiments.

Heat transfer enhancement of the air-cooled engine fins through geometrical and material analysis: A review

Energy crisis and air pollution are the two leading scientific issues that require global attention. The fundamental reason for the rise in energy costs is the rapid depletion of fossil fuels which has raised fuel prices. Analysis of IC engines suggests thatthermodynamic constraints cause more than half of energy derived from fossil fuels to be lost to the environment. Prolonged working at high temperatures can alter an engine's performance and characteristics. One way of minimizing these losses is to regulate and keep the engine's temperature within the permissible range. Thus, cylinder blocks often include extended surfaces called finsto transfer away the heat from the engine surface. This study focuses on explaining the effect of variation in material, type, design, number of fins, and other parameters in improving fins' efficiency and enhancing the engine's performance. It has been observed that the optimum number of fins can significantly improve fin efficiency, and a 5% to 13% enhancement in heat transfer is possible through fin extension. Elliptical shape fins perform better than triangular and rectangular fins. However, circular and curved fins increase engine efficiency by reducing engine weight. Amongst various fin materials like Cast Iron, Copper, Magnesium, Aluminum, and its alloys, etc., more thermal flux has been observed for Aluminium Alloy 6082. Finally, authors have come to a conclusion that circular fins with holes and slots offer a higher heat transfer rate and improved engine performance at reduced material requirements. The circular fin geometry with slots and holes provides further scope of improvement by optimizing fin thickness, number of holes and slots, their dimensions and spacing to come with a combination that provides effective cooling along with ease of manufacturing in case of lightweight engines.

Escape response kinematics in two species of tropical shark: short escape latencies and high turning performance.

Accelerative manoeuvres, such as fast-starts, are crucial for fish to avoid predation. Escape responses are fast-starts that include fundamental survival traits for prey that experience high predation pressure. However, no previous study has assessed escape performance in neonate tropical sharks. We quantitatively evaluated vulnerability traits of neonate tropical sharks by testing predictions on their fast-start escape performance. We predicted (1) high manoeuvrability, given their high flexibility, but (2) low propulsive locomotion owing to the drag costs associated with pectoral fin extension during escape responses. Further, based on previous work on dogfish, Squalus suckleyi, we predicted (3) long reaction times (as latencies longer than teleosts, >20 ms). We used two-dimensional, high-speed videography analysis of mechano-acoustically stimulated neonate blacktip reef shark, Carcharhinus melanopterus (n=12), and sicklefin lemon shark, Negaprion acutidens (n=8). Both species performed a characteristic C-start double-bend response (i.e. two body bends), but single-bend responses were only observed in N. acutidens. As predicted, neonate sharks showed high manoeuvrability with high turning rates and tight turning radii (3-11% of body length) but low propulsive performance (i.e. speed, acceleration and velocity) when compared with similar-sized teleosts and S. suckleyi. Contrary to expectations, escape latencies were <20 ms in both species, suggesting that the neurophysiological system of sharks when reacting to a predatory attack may not be limited to long response times. These results provide a quantitative assessment of survival traits in neonate tropical sharks that will be crucial for future studies that consider the vulnerability of these sharks to predation.

Experimental Investigation on Finned Solar Still With Enhanced Thermal Energy Storage

Abstract In the present study, a novel solar still incorporated with fins and phase change material (PCM)-based energy storage was designed. To investigate the influence of fins and energy storage unit, four cases of stills were considered. In case I, a conventional type was considered, whereas square hollow fins were fitted over the basin liner of the still in case II. In addition to fins as in case II, case III employs an energy storage unit wherein PCM was packed beneath the basin liner. Case IV was similar to case III except for the extension of fins into the storage unit. The addition of fins above the basin liner improved the absorber surface area and the extension of the same beneath the basin liner enhanced the storage efficiency. Experiments were carried out on all the four modules with a constant basin water depth of 2 cm. The maximum productivity of the conventional solar still was found to be 3.25 L/m2/day. On the other hand, the results reveal improvement in productivity of 17.54%, 48.61%, and 55.69% with cases II, III, and IV, respectively. Although stills with energy storage units exhibited higher exergy efficiency, the presence of fins in the PCM increases the internal irreversibilities. The cost of water yielded by modified solar still (MSS) used in case IV is proved to be less as compared to conventional solar still (CSS). Further, the payback period of MSS is found to be lesser than that of CSS.

Successive melting of a phase change material bounded in a finned trapezoidal domain

The storage of thermal energy in a trapezoidal aluminum enclosure via melting of PCM phase change material is studied. Experimental observations and numerical simulation are made to examine the process for the phase change of paraffin wax. The development of LHTES: latent heat thermal energy storage system is a promising alternate option to manage the growing imbalance of energy consumption and supply. Successive melting of paraffin Rubitherm-RT35 is designed when it is heated from one side of the frame and the remaining sides are insulated. Two configurations are examined for the heat storage material: (a) paraffin wax only via experimental set up; (b) PCM melting in a fin extended aluminum structure via simulation. From the lab set up, melt fronts of melting PCM for various time lengths are photographed. In second procedure, improvement in thermal conductivity is desired through fin extension by utilizing software Multi-physics Comsol version 5.4. Transient heat conduction and enthalpy function built in the fluid-solid module are hired. Simulation procedure is carried out with fin augmentation. The melting time is notably reduced with enhancing technique of thermal conductivity via fins.

The Genetic Architecture of Variation in the Sexually Selected Sword Ornament and Its Evolution in Hybrid Populations

Biologists since Darwin have been fascinated by the evolution of sexually selected ornaments, particularly those that reduce viability. Uncovering the genetic architecture of these traits is key to understanding how they evolve and are maintained. Here, we investigate the genetic architecture and evolutionary loss of a sexually selected ornament, the "sword" fin extension that characterizes many species of swordtail fish (Xiphophorus). Using sworded and swordless sister species of Xiphophorus, we generated a mapping population and show that the sword ornament is polygenic-with ancestry across the genome explaining substantial variation in the trait. After accounting for the impacts of genome-wide ancestry, we identify one major-effect quantitative trait locus (QTL) that explains ~5% of the overall variation in the trait. Using a series of approaches, we narrow this large QTL interval to several likely candidate genes, including genes involved in fin regeneration and growth. Furthermore, we find evidence of selection on ancestry at one of these candidates in four natural hybrid populations, consistent with selection against the sword in these populations.

High-Voltage Drain-Extended FinFET With a High-${k}$ Dielectric Field Plate

A drain-extended (De) FinFET (DeFinFET) with a high- ${k}$ dielectric field plate is proposed for high-voltage (HV) system-on-chip (SoC) applications at 10-nm CMOS technology nodes. Conventional DeFinFETs without the dielectric field plate and DeFinFETs with SiO2 and HfO2 field plate are investigated by varying the length ( ${L}_{\text {EXT}}$ ) and the doping concentration ( ${N}_{\text {EXT}}$ ) of the fin extension and the thickness ( ${T}_{\text {FOX}}$ ) of the dielectric field plate. The optimized device with the HfO2 field plate has a high breakdown voltage ( ${V}_{\text {BD}}$ ) of 8.56 V, a low specific ON-state resistance ( ${R}_{ \mathrm{\scriptscriptstyle ON}\_{}{\text {sp}}}$ ) of $6.40~\Omega \cdot \mu \text{m}^{{2}}$ , and a large figure of merit ( ${V}_{\text {BD}}^{{2}}/{R}_{ \mathrm{\scriptscriptstyle ON}\_{}{\text {sp}}}$ ) of 11.46 W/ $\mu \text{m}^{{2}}$ , which are greatly improved HV performance over other devices. This indicates that the HfO2 field plate can effectively address the tradeoff between ${V}_{\text {BD}}$ and ${R}_{ \mathrm{\scriptscriptstyle ON}\_{}{\text {sp}}}$ . In addition, the excellent electrical characteristics such as high ON-state current ( ${I}_{ \mathrm{\scriptscriptstyle ON}}$ ) of $3.07\times 10^{-{4}}$ A/ $\mu \text{m}$ , low OFF-state current ( ${I}_{ \mathrm{\scriptscriptstyle OFF}}$ ) of $6.54\times 10^{-{10}}$ A/ $\mu \text{m}$ , and small subthreshold swing (SS) of 65.54 mV/decade are observed for the optimized HfO2-DeFinFET. Consequently, the proposed design with the high- ${k}$ field plate can be a pathway to realize HV DeFinFETs for SoC technology.

The water-hopping kinematics of the tree-climbing fish, Periophthalmus variabilis

In this communication, we describe the water-hopping kinematics of the dusky-gilled mudskipper (Periophthalmus variabilis), and by doing so elucidate an entirely new form of fish locomotion that has yet to be reported in the public domain. Water-hopping is defined herein as an ability to hop once, or in succession, on the surface of water without full submergence and without a fin-guided glide. We find that taxiing on the water surface is the predominating kinematic movement used for the execution of successful water-hops. We observe that an initial concentric ripple forms as the mudskipper impacts the water, and that subsequent taxiing on the water surface generates a sinusoid-like ripple pattern in the water prior to take off. Interestingly whilst airborne, the pectoral fins of P. variabilis appear to remain stationary, only to be deployed upon contact with the water. When landing back onto the surface of the water, P. variabilis makes the initial contact via its pelvic region, occasionally extending its pectoral fins during its descent. The reasons for pectoral and pelvic fin extension are unclear, however, there may be either aerodynamic or hydrodynamic benefits in its doing so. This motion furthermore prepares the mudskipper for either, a follow-on water-hop, or a discontinuation of movement altogether, as the body of the mudskipper becomes aligned in a way conducive to either. P. variabilis will launch and land using both, horizontal surfaces such as littorals, and inclined-to-vertical surfaces such as rocks and trees.

Parasitic Gate Resistance Impact on Triple-Gate FinFET CMOS Inverter

In this paper, based on a full intrinsic–extrinsic model for symmetric doped double-gate MOSFET, we analyze the impact of FinFET gate resistance over the inverter and ring oscillator performance. It is shown that, when the total number of fins remains constant, the propagation delay can be improved thanks to the multifinger configuration that translates into the gate resistance reduction. Furthermore, the fin spacing in addition to source/drain fin extension reduction are of primary importance to improve the digital circuit performance.

(Invited) Plasma Process Simulation for Advanced Semiconductor Applications

Next generation semiconductor device technology node logic and advanced memory fabrication etch [1] deposition [2] and functionalization [3,4] unit processes require management of process chamber species’ nature, flux and energy at all facets of a substrate and feature being fabricated. Management of profile (conformality), selectivity, deposition or etch rate, uniformity, damage and/or sub-surface and film “quality” needs via continuous or quasi-continuous processes is difficult as process chemistries and plasma source characteristics drive trade-offs innate to their combination. Fortified by more than two decades of progress in modelling and simulation, concurrent process and equipment development has overcome these difficulties. It is evident now to meet trade-off born difficulties in the future that self-limiting process technology will need to be used. In this case, chemistry control may mean parsing individual process steps into adsorption and desorption components [5]. Segregating processes include rapid cyclic etch and atomic layer deposition (ALD). Other examples of self-limiting processes include radical driven plasma doping. This presentation will discuss each of these processes in the context of their needs and how simulation drives their development. Simulation models discussed are based on an integrated approach (chamber through feature) with fluxes to surfaces from plasma source simulations (e.g., HPEM [6]) mated to feature scale simulations such as MCFPM. [7] Atomic layer etching for front end applications will be described that use this suite of simulation models. [8] While atomic layer deposition is more mature than it’s etch counterpart, plasma assisted ALD comes with mechanistic complexity both in the plasma and at surface. [9] Fortunately, quantum chemistry methods, [10] surface and plasma chemistry models can be linked to equipment simulations for concurrent process design. Three dimensional devices require source drain engineering to being about conformal electrical properties. An example is fin extension doping. Radical driven plasma doping can be conformal because of the self-passivating nature of a saturation layer created all around the surface of the fin during the doping process. Functionalizing topographic structures such as silicon, Ge or III-V fins sets severe constraints on the plasma itself. Fins must not erode but sufficient ion energy is required to disorder a single surface layer so that dopants may be infused. Plasma equipment simulations show that high microwave power and high pressure operation are sufficient to generate sufficient dopant radicals with a sufficient non-damaging flux of light ions to the surface to meet functionalization requirements. [11] The properties of the surface layer are very important. Using arsenic doping of silicon as an example, first principles calculations of ternary dopant silicon oxygen system were used to explore the surface film properties. [12] The calculations show that trade-offs between strain relaxation of the amorphous and the evolution of penalty energy as arsenic is introduced to the amorphous silica system creates a preferred stoichiometry film. This is one ingredient to maintaining conformality in the presence of different flux compositions all around a feature. The presentation will close with a look forward at how the new norm in modeling and simulation will involve addition of first-principles (quantum chemistry through device) to the integrated source through feature approach of the last two decades. [1] C. T. Carver et al., ECS J. Sol. St. Sci. Tech., 4 N5005-N5009 (2015) [2] S. M. George, Chem. Rev., 110, 111 (2010) [3] K. J. Kuhn, IEEE Trans. Elec. Dev., 59, 1813 (2012) [4] T. Tatsumi and J. Lee, Jpn. J. Appl. Phys., 53, 06JE06 (2014) [5] K. Ono and M. Tuda, Thin Solid Films, 374, 208 (2000) [6] M. Wang and M. J. Kushner, J. Appl. Phys 107, 023308 (2010) [7] A. Agarwal and M. J. Kushner, J. Vac. Sci. Technol. A 26, 498 (2008) [8] A. Ranjan et al., Proc. SPIE 9428, Advanced Etch Technology for Nanopatterning IV, 94280O (2015) [9] S. King, J. Vac. Sci. Technol. A, 29, 041501(2011) [10] J. Yoshikawa, AVS 60th Annual Symposium, Paper TF+PS-ThM12(2013) [11] H. Ueda et al., J. Appl. Phys., 115, 214904 (2014) [12] P. Ventzek et al., Appl. Phys. Lett., 105, 262102 (2014)

Conformal doping of topographic silicon structures using a radial line slot antenna plasma source

Fin extension doping for 10 nm front end of line technology requires ultra-shallow high dose conformal doping. In this paper, we demonstrate a new radial line slot antenna plasma source based doping process that meets these requirements. Critical to reaching true conformality while maintaining fin integrity is that the ion energy be low and controllable, while the dose absorption is self-limited. The saturated dopant later is rendered conformal by concurrent amorphization and dopant containing capping layer deposition followed by stabilization anneal. Dopant segregation assists in driving dopants from the capping layer into the sub silicon surface. Very high resolution transmission electron microscopy-Energy Dispersive X-ray spectroscopy, used to prove true conformality, was achieved. We demonstrate these results using an n-type arsenic based plasma doping process on 10 to 40 nm high aspect ratio fins structures. The results are discussed in terms of the different types of clusters that form during the plasma doping process.

Fluid dynamics of the larval zebrafish pectoral fin and the role of fin bending in fluid transport

Larval zebrafish beat their pectoral fins during many behaviors including low-speed swimming and prey tracking; however, little is known about the functions of these fin movements. Previously, we found experimental support for the function of larval fins in mixing of fluid near the body, which may enhance respiration by diffusion of dissolved oxygen across the skin. Here we use computational fluid dynamics to analyze fluid flow due to the pectoral fin movement. The pectoral fins bend along their proximodistal axis during abduction (fin extension), but remain nearly rigid during adduction (fin flexion). We hypothesize that this asymmetry in bending is critical for fluid mixing near the body and test the effects of fin bending with our simulations. For normal fin beats, we observed similar flow patterns in simulations and experiments. Flow patterns showed fluid stretching and folding, indicative of mixing. When proximodistal bending was removed from fin motion, fins were less effective at transporting fluid in a posterior direction near the body surface, but lateral mixing of fluid near the body was unaffected. Our results suggest that fin bending enhances posterior transport of fluid along the body surface, which may act to aid respiration in combination with lateral stretching and folding of fluid.

No role for direct touch using the pectoral fins, as an information gathering strategy in a blind fish

Blind Mexican cave fish (Astyanax fasciatus) lack a functional visual system and have been shown to sense their environment using a technique called hydrodynamic imaging, whereby nearby objects are detected by sensing distortions in the flow field of water around the body using the mechanosensory lateral line. This species has also been noted to touch obstacles, mainly with the pectoral fins, apparently using this tactile information alongside hydrodynamic imaging to sense their surroundings. This study aimed to determine the relative contributions of hydrodynamic and tactile information during wall following behaviour in blind Mexican cave fish. A wall was custom built with a 'netted' region in its centre, which provided very similar tactile information to a solid tank wall, but was undetectable using hydrodynamic imaging. The fish swam significantly closer to and collided more frequently with the netted region of this wall than the solid regions, indicating that the fish did not perceive the netted region as a solid obstacle despite being able to feel it as such with their pectoral fins. We conclude that the touching of objects with the pectoral fins may be an artefact of the intrinsic link between pectoral fin extensions and tail beating whilst swimming, and does not function to gather information. During wall following, hydrodynamic information appears to be used strongly in preference to tactile information in this non-visual system.

Implications of fin width scaling on variability and reliability of high-k metal gate FinFETs

In this paper, we report a study to understand the fin width dependence on performance, variability and reliability of n-type and p-type triple-gate fin field effect transistors (FinFETs) with high-k dielectric and metal gate. Our results indicate that with decreasing fin width the well-known performance improvement in terms of sub-threshold swing and drain-induced barrier lowering are accompanied by a degradation of the variability and the reliability. As a matter of fact fin width scaling causes (i) higher hot-carrier degradation (HC) in nFinFETs owing to the higher charge carrier temperature for the same internal stress voltages; (ii) worse negative bias temperature instability (NBTI) in pFinFETs due to the increased contribution from the (1 1 0) surface; (iii) higher variability due to the non-uniform fin extension doping, as highlighted by applying a novel characterization technique.

Fgfr1 signalling in the development of a sexually selected trait in vertebrates, the sword of swordtail fish

BackgroundOne of Darwin's chosen examples for his idea of sexual selection through female choice was the "sword", a colourful extension of the caudal fin of male swordtails of the genus Xiphophorus. Platyfish, also members of the genus Xiphophorus, are thought to have arisen from within the swordtails, but have secondarily lost the ability to develop a sword. The sustained increase of testosterone during sexual maturation initiates sword development in male swordtails. Addition of testosterone also induces sword-like fin extensions in some platyfish species, suggesting that the genetic interactions required for sword development may be dormant, rather than lost, within platyfish. Despite considerable interest in the evolution of the sword from a behavioural or evolutionary point of view, little is known about the developmental changes that resulted in the gain and secondary loss of the sword. Up-regulation of msxC had been shown to characterize the development of both swords and the gonopodium, a modified anal fin that serves as an intromittent organ, and prompted investigations of the regulatory mechanisms that control msxC and sword growth.ResultsBy comparing both development and regeneration of caudal fins in swordtails and platyfish, we show that fgfr1 is strongly up-regulated in developing and regenerating sword and gonopodial rays. Characterization of the fin overgrowth mutant brushtail in a platyfish background confirmed that fin regeneration rates are correlated with the expression levels of fgfr1 and msxC. Moreover, brushtail re-awakens the dormant mechanisms of sword development in platyfish and activates fgfr1/msxC-signalling. Although both genes are co-expressed in scleroblasts, expression of msxC in the distal blastema may be independent of fgfr1. Known regulators of Fgf-signalling in teleost fins, fgf20a and fgf24, are transiently expressed only during regeneration and thus not likely to be required in developing swords.ConclusionOur data suggest that Fgf-signalling is involved upstream of msxC in the development of the sword and gonopodium in male swordtails. Activation of a gene regulatory network that includes fgfr1 and msxC is positively correlated with fin ray growth rates and can be re-activated in platyfish to form small sword-like fin extensions. These findings point towards a disruption between the fgfr1/msxC network and its regulation by testosterone as a likely developmental cause for sword-loss in platyfish.