Tail Function Research Articles

A Pareto tail plot without moment restrictions

We propose a mean functional that exists for arbitrary probability distributions and characterizes the Pareto distribution within the set of distributions with finite left endpoint. This is in sharp contrast to the mean excess plot, which is meaningless for distributions without an existing mean and has non-standard behavior when the mean is finite, but the second moment does not exist. The construction of the plot is based on the principle of a single huge jump, which differentiates between distributions with moderately heavy and super heavy tails. We present an estimator of the tail function based on U-statistics and study its large sample properties. Several loss datasets illustrate the use of the new plot.

A Robust SVD-UKF Algorithm and Its Application in Integrated Navigation Systems

To improve the positioning accuracy in Inertial Navigation System/Global Navigation Satellite System (INS/GNSS) integrated navigation and address the issue of measurement information anomalies, an integrated navigation algorithm based on an improved Huber-M estimation with Singular Value Decomposition Unscented Kalman Filter (SVD-UKF) is proposed. During the iterative update process of the prior information matrix in the UKF filtering, the Singular Value Decomposition (SVD) is introduced. This enhancement optimizes the prior information matrix, thereby enhancing numerical stability. The tail function of the Huber-M estimation is replaced with an exponential square loss function to improve the computational accuracy of the Huber-M estimation. The improved Huber-M estimation is then incorporated into the SVD-UKF framework. This approach reconstructs the UKF prior information and measurement information. The experimental results indicate that, compared to the traditional UKF and the Sage-Husa adaptive SVD-UKF algorithm, the improved algorithm enhances velocity accuracy by 68.7% and 31.2%, respectively, and improves position accuracy by 73.5% and 38.6%, respectively. The positioning accuracy and robustness of the INS/GNSS integrated navigation system were significantly improved, particularly under conditions with abnormal measurement information. The system demonstrated enhanced stability and resistance to interference in these scenarios.

Spinal neuron diversity scales exponentially with swim-to-limb transformation during frog metamorphosis.

Vertebrates exhibit a wide range of motor behaviors, ranging from swimming to complex limb-based movements. Here we take advantage of frog metamorphosis, which captures a swim-to-limb-based movement transformation during the development of a single organism, to explore changes in the underlying spinal circuits. We find that the tadpole spinal cord contains small and largely homogeneous populations of motor neurons (MNs) and V1 interneurons (V1s) at early escape swimming stages. These neuronal populations only modestly increase in number and subtype heterogeneity with the emergence of free swimming. In contrast, during frog metamorphosis and the emergence of limb movement, there is a dramatic expansion of MN and V1 interneuron number and transcriptional heterogeneity, culminating in cohorts of neurons that exhibit striking molecular similarity to mammalian motor circuits. CRISPR/Cas9-mediated gene disruption of the limb MN and V1 determinants FoxP1 and Engrailed-1, respectively, results in severe but selective deficits in tail and limb function. Our work thus demonstrates that neural diversity scales exponentially with increasing behavioral complexity and illustrates striking evolutionary conservation in the molecular organization and function of motor circuits across species.

Biomechanics and morphological comparisons of the caudal region of titanosaurs from the Cretaceous of Brazil: Paleobiology and paleoecology inferences.

Biomechanical studies in sauropod dinosaurs are mainly focused on neck posture and feeding strategy. Few works investigate other aspects such as tail movement and function, especially in the clade Titanosauria, the most diverse within Neosauropoda. This study applied biomechanical concepts of neutral pose (cartilaginous neutral pose) and range of motion to verify the shape and direction of the caudal region of the advanced titanosaurs Adamantisaurus mezzalirai and Baurutitan britoi, in addition to comparing it with other titanosaurs (e.g., Arrudatitan maximus, Lirainosaurus astibiae, and Trigonosaurus pricei). As a result, the tails analyzed have a sigmoidal-convex shape, probably close to the ground (but not touching it). The sigmoidal-convex shape could increase the moment arm for the M. caudofemoralis longus, making it possible to use the tail as a fifth stabilizing member. This work expands our knowledge about sauropod dinosaurs by exposing a diversity of shapes for the tails of titanosaur sauropods and brings new possibilities for how these dinosaurs could use their tails.

ArborSim: Articulated, branching, OpenSim routing for constructing models of multi-jointed appendages with complex muscle-tendon architecture.

Computational models of musculoskeletal systems are essential tools for understanding how muscles, tendons, bones, and actuation signals generate motion. In particular, the OpenSim family of models has facilitated a wide range of studies on diverse human motions, clinical studies of gait, and even non-human locomotion. However, biological structures with many joints, such as fingers, necks, tails, and spines, have been a longstanding challenge to the OpenSim modeling community, especially because these structures comprise numerous bones and are frequently actuated by extrinsic muscles that span multiple joints-often more than three-and act through a complex network of branching tendons. Existing model building software, typically optimized for limb structures, makes it difficult to build OpenSim models that accurately reflect these intricacies. Here, we introduce ArborSim, customized software that efficiently creates musculoskeletal models of highly jointed structures and can build branched muscle-tendon architectures. We used ArborSim to construct toy models of articulated structures to determine which morphological features make a structure most sensitive to branching. By comparing the joint kinematics of models constructed with branched and parallel muscle-tendon units, we found that among various parameters-the number of tendon branches, the number of joints between branches, and the ratio of muscle fiber length to muscle tendon unit length-the number of tendon branches and the number of joints between branches are most sensitive to branching modeling method. Notably, the differences between these models showed no predictable pattern with increased complexity. As the proportion of muscle increased, the kinematic differences between branched and parallel models units also increased. Our findings suggest that stress and strain interactions between distal tendon branches and proximal tendon and muscle greatly affect the overall kinematics of a musculoskeletal system. By incorporating complex muscle-tendon branching into OpenSim models using ArborSim, we can gain deeper insight into the interactions between the axial and appendicular skeleton, model the evolution and function of diverse animal tails, and understand the mechanics of more complex motions and tasks.

Practicality of in-kernel/user-space packet processing empowered by lightweight neural network and decision tree

Integrating machine learning (ML) into kernel packet processing, such as extended Berkeley Packet Filter (eBPF) and eXpress Data Path (XDP), represents a promising strategy for achieving fast and intelligent networking on generic hardware. This includes tasks like automating network operations and discerning traffic classification, exemplified by intrusion detection systems (IDS) combining Decision Tree (DT) and eBPF. However, the potential of ML-empowered packet processing remains to be fully explored. To ensure the integrity and security of kernel operations, eBPF/XDP programs must adhere to stringent constraints such as the maximum number of jump instructions, maximum stack space, and exclusion of floating-point arithmetic. These constraints pose challenges for implementing more intricate ML techniques (e.g., neural networks (NNs)) within eBPF/XDP programs. In such scenarios, AF_XDP provides an alternative solution by allowing XDP programs to redirect packets to user-space applications, bypassing the network stack. This paper initiates an exploration into fast packet classification through two distinct approaches: (1) an in-kernel approach employing eBPF/XDP and (2) a user-space approach assisted by AF_XDP. Specifically, to tackle the eBPF constraints, the in-kernel NN classifier adopts (1) quantization of trained model in the user space, (2) executing the integer-arithmetic-only NN within the kernel space, and (3) sequential layer operations through tail calls. These approaches are evaluated based on factors including packet processing speed, resource efficiency, and detection performance. Notably, our experimental findings demonstrate that (1) Classifiers relying solely on integer arithmetic, such as NN and DT, significantly reduce inference time while maintaining binary classification performance; (2) The lightweight NN classifier can improve the detection performance for most of attacks in case of the multi-class classification compared to the lightweight DT classifier; (3) In single-core scenarios, the DT-empowered in-kernel method can almost achieve the maximum packets per second (pps), i.e., about 800,000pps, whereas the NN-empowered one exhibits lower pps (i.e., about 450,000pps); (4) In multi-core scenarios, the NN-empowered packet processing can almost achieve the maximum pps with two or more cores in the AF_XDP approach and four or more cores in the in-kernel approaches.

Método de avaliação para identificação de bloqueio da cauda de equinos

ABSTRACT This study aims to standardize the clinical and complementary examination using surface electromyography (EMG) to assess the neuromuscular function of the equine tail. Firstly, clinical examinations of the tails and EMG measurements were performed on ten healthy animals without any tail interference or manipulation. This initial experiment aimed to establish a baseline for clinical examination and EMG results. The animals underwent tail nerve plexus blockade in the second experiment using an anesthetic agent. The objective compares the clinical examination and EMG findings between the anesthetized and non-manipulated tails. Finally, two animals were used in the third experiment, where peripheral infiltration of the tail nerve plexuses was performed using a neurolytic agent. The study successfully obtained a pattern for the clinical examination of a healthy equine tail and established a pattern for the clinical examination of a tail after infiltration with anesthetic and neurolytic agents. Significant differences were observed in the clinical examination before and after the application of local anesthesia, as well as in the EMG values before and after local infiltration with anesthetic (P=0.04) and neurolytic agent (P=0.03). The presented study introduces a clinical examination protocol that utilizes surface electromyography as a diagnostic tool for cauda equina block.

Tail Call Optimization Tailored for Native Stack Utilization in JavaScript Runtimes

Tail Call Optimization Tailored for Native Stack Utilization in JavaScript Runtimes

Pitch posture regulation in Peking geckos (Gekko swinhonis): assessing the role of tails before take-off in upward jumping

Abstract Small vertebrates, such as geckos, often use their tails to regulate their posture after take-off and suppress abnormal rotations in mid-air (such as sliding and falling). However, research on tail function before take-off remains scarce, particularly when animals overcome gravity to jump upward. This study examined tailed and tailless geckos’ ability to jump over obstacles. The tails swung up and reached their upper limits during take-off, corresponding to a continuous increase in their trunk elevation angle. Compared to tailless geckos, geckos with intact tails had lower body and tail angular velocities. In addition, tailed geckos achieved larger take-off angles and higher jumps; moreover, their take-off angles were consistent with their velocity angles. Theoretical analyses demonstrated that the tail and its upward swing before take-off could benefit lifting the forelimb and hindlimbs off the ground, expanding the stability area of their centre of mass (COM). A robot prototype verified the effect of the tail and its swing on trunk elevation before take-off. Other parameters, such as the posture of the hindlimbs (support length and angle) and initial angle of the trunk, affect posture regulation. This study significantly extends our knowledge in animal locomotion and provides indispensable information for improving robot jumping ability.

Diplomatic complexity and long-tailed distributions: the function of non-strategic bilateral relations

AbstractStates enact relations with both important partners and seemingly irrelevant countries. The non-strategic constitutes the larger set; a histogram could visualize them in a long-tailed distribution, with the x-axis denoting the partner countries, and the y-axis showing the interaction density. Investigating the function of this long tail, this paper premises that the international is characterized by complexity, meaning that the number of elements is so large that it is impossible to realize all relations simultaneously. States thus select their diplomatic partners based on power-rationales. The thereby inactive nodes nevertheless pose sources of danger, requiring occasional signals of amity—hence a long tail comes about. A repertoire of cheap and quick but unambiguously sovereign practices (such as Twiplomacy, gifts, or honorary consulates) can be spontaneously activated to fill otherwise neglected inter-state ties. Seemingly trivial gestures thus ensure peace among plural polities under the constraint of systemic complexity.

Thermal Drone Technology Used to Capture Thermoregulation in Wild Sumatran Elephants

Drone technology plays a critical role in supporting conservation efforts for endangered species, not only in terms of species monitoring within various landscapes, but also potentially when applied to behavioral studies to investigate interaction patterns and response to environmental change. We tested a thermal drone to investigate thermoregulation and surface temperature of wild Sumatran elephants in the lowland tropical forest of Jambi, Indonesia. Thermoregulation data was obtained using RGB images and videos, while temperature values were measured from thermal images (R-JPEG) extracted into TIFF equipped with pixel temperature. We detected a visual thermoregulation mechanism known as mud bathing. Our study demonstrated that the trunk functions to draw mud and throw it onto the head, back, and stomach, the tail functions to distribute the mud to all parts of the back of the body, while the ears flapped to keep head temperature cool. Our measurements showed that the surface temperature of Sumatran elephants is between 28.9-30.3°C. The head had a relatively lower temperature than other body parts. This study also revealed that the environmental humidity variable significantly affects the elephant's temperature rise. The use of drone technology for future behavioral studies is recommended as it accurately provides high quality data and can be widely used in any type of terrain.

Electrospinning and Optical Properties of Polyacrylonitrile/Titanium Dioxide Nanocomposite Fibers

In situ polymerization was used in this work to prepare polyacrylonitrile (PAN) and titanium dioxide (TiO2) nanocomposite at various ratios (5, 10, 15, and 20 weight percent of TiO2). PAN/TiO2 nanofibers were created using the electrospinning process from a homogenized solution. X-ray diffraction data demonstrated that a structural change to an amorphous state had taken place. Using scanning electron microscopy (SEM), the morphology of the high-aligned fibers with PAN diameters of roughly 33 nm and 51 nm of PAN/(10wt%)TiO2 was examined. A spectrophotometer was used to examine the optical characteristics of the nanofiber films at wavelengths between 200 and 900 nm. The energy gap (Eg) of the nanofiber films was computed, and it decreased as the weight ratio of the TiO2 nanoparticle increased. With 5, 10, and 15% weight percentage of TiO2, respectively, the energy gap (Eg) of PAN nanofibers changes from 3.92 eV to 3.72, 3.39, 3.19 eV. Several other parameters have also been calculated, including the excitation coefficient (k), refractive index (n), Urbach tail (Et), dielectric constant (e1), dielectric loss (e2), and volume and surface energy loss functions (VELF) and (SELF).

Mathematic modeling of the dose in water for calculating collimator scatter factor of flattening filter and flattening filter free megavoltage photon beams

This study presents an empirical method to model the percent depth dose (PDD) curves of flattening filter (FF) and FF-free (FFF) high-energy photon beams using a home-generated buildup function and tail function (buildup-tail function) in radiation therapy. The modeling parameters n and μ of the buildup-tail function were used to characterize the collimator scatter factor (Sc). The buildup function was a quadratic function in the form of d/ √(d2 + n) with main parameters of d (depth in water) and n, while the tail function was in the form of e−μd and was composed of an exponential function with d and μ. PDD was the product of buildup-tail function and characterized by the buildup-tail function by adjusting the parameters n and μ. The Sc of 6 and 10 MV in FF and FFF beams can be expressed simply by the modeling parameters n and μ. The main parameter n increases when photon energy increases. Its physical meaning expresses the beam hardening of photon energy in PDD. The parameter μ can be treated as an attenuation coefficient in the tail function, decreasing when photon energy increases. The values of n and μ obtained from the fitted buildup-tail function were applied into an analytical formula of Sc,FF = nE(S)0.63 μ E, Sc,FFF = nE(S)4.45 μ E to get the Sc of 6 and 10 MV in FF and FFF photon beams, with nE, μ E, S denoting n and μ at photon energy E of field size S. The calculated Sc was compared with the measured data and showed agreement, finding that the field difference was size within ±1%. This model can be used to parameterize the Sc for some clinical requirements. The modeling parameters n and μ can be used to predict the Sc in either FF or FFF beams for the treatment monitor unit in double-check dose calculation. The technique developed in this study can also be used for systematic or random errors in the quality assurance program, thus improving the clinical dose computation accuracy for patient treatment.

Reliable Actors with Retry Orchestration

Cloud developers have to build applications that are resilient to failures and interruptions. We advocate for a fault-tolerant programming model for the cloud based on actors, retry orchestration, and tail calls. This model builds upon persistent data stores and message queues readily available on the cloud. Retry orchestration not only guarantees that (1) failed actor invocations will be retried but also that (2) completed invocations are never repeated and (3) it preserves a strict happen-before relationship across failures within call stacks. Tail calls can break complex tasks into simple steps to minimize re-execution during recovery. We review key application patterns and failure scenarios. We formalize a process calculus to precisely capture the mechanisms of fault tolerance in this model. We briefly describe our implementation. Using an application inspired by a typical enterprise scenario, we validate the functional correctness of our implementation and assess the impact of fault preparedness and recovery on performance.

Broad compatibility between yeast UAS elements and core promoters and identification of promoter elements that determine cofactor specificity

Three classes of yeast protein-coding genes are distinguished by their dependence on the transcription cofactors TFIID, SAGA, and Mediator (MED) Tail, but whether this dependence is determined by the core promoter, upstream activating sequences (UASs), or other gene features is unclear. Also unclear is whether UASs can broadly activate transcription from the different promoter classes. Here, we measure transcription and cofactor specificity for thousands of UAS-core promoter combinations and find that most UASs broadly activate promoters regardless of regulatory class, while few display strong promoter specificity. However, matching UASs and promoters from the same gene class is generally important for optimal expression. We find that sensitivity to rapid depletion of MED Tail or SAGA is dependent on the identity of both UAS and core promoter, while dependence on TFIID localizes to only the promoter. Finally, our results suggest the role of TATA and TATA-like promoter sequences in MED Tail function.

Specifying and Verifying a Transformation of Recursive Functions into Tail-Recursive Functions

It is well known that some recursive functions admit a tail recursive counterpart which have a more efficient time-complexity behavior. This paper presents a formal specification and verification of such process. A monoid is used to generate a recursive function and its tail-recursive counterpart. Also, the monoid properties are used to prove extensional equality of both functions. In order to achieve this goal, the Agda programming language and proof assistant is used to generate a parametrized module with a monoid, via dependent types. This technique is exemplified with the length, reverse, and indices functions over lists.

Improved confidence estimation for the binomial proportion with applications to clinical studies

ABSTRACT In this paper, we establish a frequentist framework that incorporates all confidence sets with guaranteed frequentist coverage probability for the binomial proportion, where different confidence sets are completely characterized by their tail functions. Based on measures of precision in the form of interval length, probability of false coverage, and a new evaluation criterion utilizing prior information, we construct the optimal confidence set for the binomial proportion. The newly proposed methodology is applied to clinical studies. It is shown that confidence intervals obtained via the tail functions are often better than prevailing confidence intervals in view of precision.

Tail Recursion Modulo Context: An Equational Approach

The tail-recursion moduloconstransformation can rewrite functions that are not quite tail-recursive into a tail-recursive form that can be executed efficiently. In this article we generalize tail recursion modulocons(TRMc) to modulocontexts(TRMC), and calculate a general TRMC algorithm from its specification. We can instantiate our general algorithm by providing an implementation of application and composition on abstract contexts, and showing that ourcontextlaws_ hold. We provide some known instantiations of TRMC, namely moduloevaluation contexts(CPS), andassociative operations, and further instantiantions not so commonly associated with TRMC, such asdefunctionalizedevaluation contexts,monoids,semirings,exponents, andcons products. We study the moduloconsinstantiation in particular and prove that an instantiation using Minamide’s hole calculus is sound. We also calculate a second instantiation in terms of the Perceus heap semantics to precisely reason about the soundness of in-place update. While all previous approaches to TRMc fail in the presence of non-linear control (for example induced by call/cc, shift/reset or algebraic effect handlers), we can elegantly extend the heap semantics to a hybrid approach which dynamically adapts to non-linear control flow. We have a full implementation of hybrid TRMc in the Koka language and our benchmark shows the TRMc transformed functions are always as fast or faster than using manual alternatives.

Folding left and right matters: Direct style, accumulators, and continuations

Abstract The equivalence of folding left and right over Peano numbers and lists makes it possible to minimalistically inter-derive (1) structurally recursive functions in direct style, (2) structurally tail-recursive functions that use an accumulator, and (3) structurally tail-recursive functions in delimited continuation-passing style, using Ohori and Sasano’s lightweight fusion by fixed-point promotion. When the fold-left and the fold-right functions account for primitive iteration for Peano numbers, this equivalence is unconditional. When they account for primitive recursion for Peano numbers, this equivalence is modulo left permutativity of their induction-step parameter – a property which is more general than associativity and commutativity. And when they account for primitive iteration or for primitive recursion over lists, this equivalence is modulo left permutativity of their induction-step parameter if these two fold functions have the same type. Since the 1980s, however, the two fold functions for lists do not have the same type: the arguments for their induction-step parameter are swapped, a re-ordering that complicated Bird and Wadler’s duality theorems and whose history is reviewed in an appendix. Without this re-ordering, Bird and Wadler’s second duality theorem more visibly accounts for “re-bracketing,” which is a key step to make recursive programs tail recursive in the general area of program development, from Cooper in the 1960s and onwards.

Multibody analysis and soft tissue strength refute supersonic dinosaur tail.

Sauropod dinosaurs are well known for their massive sizes and long necks and tails. Among sauropods, flagellicaudatan dinosaurs are characterized by extreme tail elongation, which has led to hypotheses regarding tail function, often compared to a whip. Here, we analyse the dynamics of motion of a 3D model of an apatosaurine flagellicaudatan tail using multibody simulation and quantify the stress-bearing capabilities of the associated soft tissues. Such an elongated and slender structure would allow achieving tip velocities in the order of 30m/s, or 100km/h, far slower than the speed of sound, due to the combined effect of friction of the musculature and articulations, as well as aerodynamic drag. The material properties of the skin, tendons, and ligaments also support such evidence, proving that in life, the tail would not have withstood the stresses imposed by travelling at the speed of sound, irrespective of the conjectural 'popper', a hypothetical soft tissue structure analogue to the terminal portion of a bullwhip able to surpass the speed of sound.