Time Signature Research Articles

Spatiotemporal evolution of emission and absorption signatures in a laser-produced plasma

We report spatiotemporal evolution of emission and absorption signatures of Al species in a nanosecond (ns) laser-produced plasma (LPP). The plasmas were generated from an Inconel target, which contained ∼0.4 wt. % Al, using 1064 nm, ≈6 ns full width half maximum pulses from an Nd:YAG laser at an Ar cover gas pressure of ≈34 Torr. The temporal distributions of the Al I (394.4 nm) transition were collected from various spatial points within the plasma employing time-of-flight (TOF) emission and laser absorption spectroscopy, and they provide kinetics of the excited state and ground state population of the selected transition. The emission and absorption signatures showed multiple peaks in their temporal profiles, although they appeared at different spatial locations and times after the plasma onset. The absorption temporal profiles showed an early time signature representing shock wave propagation into the ambient gas. We also used emission and absorption spectral features for measuring various physical properties of the plasma. The absorption spectral profiles are utilized for measuring linewidths, column density, and kinetic temperature, while emission spectra were used to measure excitation temperature. A comparison between excitation and kinetic temperature was made at various spatial points in the plasma. Our results highlight that the TOF measurements provide a resourceful tool for showing the spatiotemporal LPP dynamics with higher spatial and temporal resolution than is possible with spectral measurements but are difficult to interpret without additional information on excitation temperatures and linewidths. The combination of absorption and emission TOF and spectral measurements thus provides a more complete picture of LPP spatiotemporal dynamics than is possible using any one technique alone.

A self-adaptive deep learning model for building electricity load prediction with moving horizon

A self-adaptive deep learning model powered by ranking selection-based particle swarm optimisation (RSPSO) is developed to predict electricity load in buildings with moving horizons. The main features of the load prediction model include its self-adaptability, repeatability, robustness and accuracy. In real-world building applications, the relationship among weather data, time signature and electricity load is quite complicated. In the proposed self-adaptive deep learning model, a deep learning model with multiple hidden layers is implemented to improve prediction precision. Meanwhile, RSPSO is implemented to select the network’s optimum architecture, which involves discrete variables (i.e. the quantity of neurons in each layer and the quantity of hidden layers) and categorical variables (i.e. activation function in each layer and learning approach). Moreover, the moving horizon approach is adopted to update the architecture and structure of the dynamic deep learning model while enabling its capability in capturing the latest featuring patterns in the electricity load of the building. The proposed load prediction model is tested with the local meteorological profile and electricity load of an educational building. The self-adaptive load prediction model is identified to be the most effective at forecasting the next horizon’s energy consumption, while its prediction performance would deteriorate with the increase of time. The mean squared error, mean absolute error, and coefficient of determination of the proposed prediction model are within the range of 4.48 kW–11.23 kW, 1.28 kW–2.31 kW and 97.52%–98.92%, respectively, demonstrating its prediction accuracy and repeatability. When Gaussian white noise is added to meteorological data, the increase in mean absolute error is within the range of 2.08%–15.33%, demonstrating the robustness of the proposed prediction model in overcoming uncertainty in the weather forecast. Therefore, the proposed accurate, robust, repeatable and self-adaptive load prediction model can be rooted in practical energy management systems thus facilitate building operation and system control.

A Novel Pulsed Eddy Current Criterion for Non-Ferromagnetic Metal Thickness Quantifications under Large Liftoff.

The pulsed eddy current (PEC) inspection is considered a versatile non-destructive evaluation technique, and it is widely used in metal thickness quantifications for structural health monitoring and target recognition. However, for non-ferromagnetic conductors covered with non-uniform thick insulating layers, there are still deficiencies in the current schemes. The main purpose of this study is to find an effective feature, to measure wall thinning under the large lift-off variations, and further expand application of the PEC technology. Therefore, a novel method named the dynamic apparent time constant (D-ATC) is proposed based on the coil-coupling model. It associates the dynamic behavior of the induced eddy current with the geometric dimensions of the non-ferromagnetic metallic component by the time and amplitude features of the D-ATC curve. Numeral calculations and experiments show that the time signature is immune to large lift-off variations.

Spectral-timing of AGN ionized outflows with Athena

ABSTRACT Spectral-timing techniques have proven valuable in studying the interplay between the X-ray corona and the accretion disc in variable active galactic nuclei (AGNs). Under certain conditions, photoionized outflows emerging from central AGN regions also play a role in the observable spectral-timing properties of the nuclear components. The variable ionizing flux causes the intervening gas to ionize or recombine, resulting in a time-dependent absorption spectrum. Understanding the spectral-timing properties of these outflows is critical not only for the determination of their role in the AGN environment but also for the correct interpretation of timing signatures of other AGN components. In this paper, we test the capabilities of the Athena X-IFU instrument in studying the spectral and spectral-timing properties of a black hole system displaying a variable outflow. We take the narrow-line Seyfert 1 IRAS 13224−3809 as a test case. Our findings show that while the non-linear response of the absorbing medium can result in complex behaviour of time lags, the resulting decrease in the coherence can be used to constrain gas density and distance to the central source. Ultimately, modelling the coherence spectra of AGN outflows may constitute a valuable tool in studying the physical properties of the outflowing gas.

Approximate and Convenient Time Signatures. Rubato Notation in Alexander Scriabin’s Early Preludes

Many of Alexander Scriabin’s preludes feature quixotic or rhythmically inaccurate notation, including time signatures that do not correlate with rhythmic events in the foreground. From the standpoint of performance practice, I introduce an interpretive approach that focusses on rubato as a causal factor of Scriabin’s notational idiosyncrasies and argue that they represent an act of selfanalysis, pointing to a conscious imprint of pre-compositional planning on the final product in the choice of metric notation. In this study, preludes are classified according to two criteria: (1) the type of primary metrical dissonance they engender, which includes Type A rubato, i.e., an expressive anticipation or ornamentation of the melodic line against the accompaniment in strict time, and Type B rubato – temporary displacement of the entire texture; and (2) the type of approximation in time signature notation. The focus of this study are the early preludes (up to 1903) as Scriabin’s attention in the later preludes appears to increasingly turn toward the harmonic dissonance and away from rubato and hand synchronisation issues. I present notational variants to three preludes from op. 11 that serve as an investigative tool into Scriabin’s compositional process. Finally, I offer suggestions regarding performance considerations as well as the historical evaluation of Scriabin’s oeuvre in light of the analyses presented in this study.

Device fingerprinting using deep convolutional neural networks

Device fingerprinting is a problem of identifying a network device using network traffic data to secure against cyber-attacks. Automated device classification from a large set of network traffic features space is challenging for the devices connected in the cyberspace. In this work, the idea is to define a device-specific unique fingerprint by analysing solely inter-arrival time of packets as a feature to identify a device. Neural networks are the universal function approximation which learn abstract, highlevel, nonlinear representation of training data. Deep convolution neural network is used on images of inter-arrival time signature for device fingerprinting of 58 non-IoT devices of 5-11 types. To evaluate the performance, we compared ResNet-50 layer and basic CNN-5 layer architectures. We observed that device type identification models perform better than device identification. We also found that when deep learning models are attacked over device signature, the models identify the change in signature, and classify the device in the wrong class thereby the classification performance of the models degrades. The performance of the models to detect the attacks are significantly different from each other though both models indicate the system under attack.

Axion string signatures: a cosmological plasma collider

We study early and late time signatures of both QCD axion strings and hyperlight axion strings (axiverse strings). We focus on charge deposition onto axion strings from electromagnetic fields and subsequent novel neutralizing mechanisms due to bound state formation. While early universe signatures appear unlikely, there are a plethora of late time signatures. Axion strings passing through galaxies obtain a huge charge density, which is neutralized by a dense plasma of bound state Standard Model particles forming a one dimensional “atom”. The charged wave packets on the string, as well as the dense plasma outside, travel at nearly the speed of light along the string. These packets of high energy plasma collide with a center of mass energy of up to 109 GeV. These collisions can have luminosities up to seven orders of magnitude larger than the solar luminosity, and last for thousands of years, making them visible at radio telescopes even when they occur cosmologically far away. The new observables are complementary to the CMB observables for hyperlight axion strings that have been recently proposed, and are sensitive to a similar motivated parameter range.

SCARE: Side Channel Attack on In-Memory Computing for Reverse Engineering

In-memory computing (IMC) architectures provide a much needed solution to energy-efficiency barriers posed by Von-Neumann computing. The functions implemented in such in-memory architectures are often proprietary and constitute confidential intellectual property (IP). Our studies indicate that IMC architectures implemented using resistive RAM (RRAM) are susceptible to side channel attack (SCA). Unlike the conventional SCAs that are aimed to leak private keys from cryptographic implementations, SCA on IMC for reverse engineering (SCARE) can reveal the sensitive IP implemented within the memory through power/timing side channels. Therefore, the adversary does not need to perform invasive reverse engineering (RE) to unlock the functionality. We demonstrate SCARE by taking recent IMC architectures, such as dynamic computing in memory (DCIM) and memristor-aided logic (MAGIC) as test cases. Simulation results indicate that AND, OR, and NOR gates (which are the building blocks of complex functions) yield distinct power and timing signatures based on the number of inputs, making them vulnerable to SCA. We show that adversary can use templates (using foundry-calibrated simulations or fabricating known functions in test chips) and analysis to identify the structure of the implemented function by testing a limited number of patterns. We also propose countermeasures, such as redundant inputs and expansion of literals. Redundant inputs can mask the IP with 25% area and 20% power overhead. However, functions can be found at higher RE effort. Expansion of literals incurs 36% power overhead. However, it imposes a brute force search increasing the adversarial RE effort by <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3.04\times $ </tex-math></inline-formula> .

The Effects of Odd Time Signatures on Pop Song Enjoyment

Odd time signatures are a music theory concept and are not used often in modern pop music. Additionally, a significant issue of unoriginality is occurring in the modern pop song genre, and very little research has been conducted on time signatures. A study was conducted on how the time signature of a song impacts the enjoyment of a pop song in order to find a solution for artists to improve the quality of their songs. High school music students listened to both previously released pop songs and self-composed variations on a single pop song, rating each song after each listen in order to find this solution. The average enjoyment of all of the ratings of common time signature pop songs were statistically compared to the average enjoyment of all of the ratings of odd time signature pop songs. The previously released pop song segment of the study found that previously released common time signature pop songs were enjoyed significantly more than previously released odd time signature pop songs, but this part may have been subject to dramatic confounding variables. The second part of the study found that there was no significant difference in the average enjoyment of odd time signature variations than the average enjoyment of common time signature variations. These results imply that fans of pop artists would enjoy their songs no less depending on the time signature, and thus pop song artists can increase the originality of their songs by utilizing odd time signatures with almost no consequence.

Measurement of differential tt¯ production cross sections in the full kinematic range using lepton+jets events from proton-proton collisions at s=13 TeV

Measurements of differential and double-differential cross sections of top quark pair ($\text{t}\overline{\text{t}}$) production are presented in the lepton+jets channels with a single electron or muon and jets in the final state. The analysis combines for the first time signatures of top quarks with low transverse momentum $p_\text{T}$, where the top quark decay products can be identified as separated jets and isolated leptons, and with high $p_\text{T}$, where the decay products are collimated and overlap. The measurements are based on proton-proton collision data at $\sqrt{s} = $ 13 TeV collected by the CMS experiment at the LHC, corresponding to an integrated luminosity of 137 fb$^{-1}$. The cross sections are presented at the parton and particle levels, where the latter minimizes extrapolations based on theoretical assumptions. Most of the measured differential cross sections are well described by standard model predictions with the exception of some double-differential distributions. The inclusive $\text{t}\overline{\text{t}}$ production cross section is measured to be $\sigma_{\text{t}\overline{\text{t}}} = $ 791 $\pm$ 25 pb, which constitutes the most precise measurement in the lepton+jets channel to date.

Singing Philosophy: Deviating Voices and Rhythms without a Time Signature

AbstractThis text practices a philosophical voice that deviates from visuo-centric theory and the muteness of its language and instead sings a complex simultaneity of things and thoughts that burn through the walls of the discipline and illuminate the activities at the margins. This philosophical voice sings a refrain of “I,” which brings us back to bring us forward, surprising us in its renewal again and again. It is a body that is, as Samuel Beckett’sNot I, at once not I and I; an idiosyncratic subjectivity that carries its plural name in its mouth. In this way, it further diffracts the sonic possibility of counterfactual slices into simultaneous dimensionalities open to our gaze in the dark, when we have let go of a normative orientation and are able to see the image at its depth. Between text scores, Churten theory, Canto Cardenche, and the breath of a humpback whale, this voice tries not to theorise. It does not want to produce a philosophical message, supporting a “philosophism” which akin to “scientism” treats philosophy as a phenomenon unconnected to cultural values or location, gender or racial specificity. Instead, it aims to practice a philosophy that opens in song to its own anxiety of objectivity, its fear of a reflective centre, and performs a translucent marginality that generates the view of a plural world burning through a permeable skin.

The role of key IN CREATING AN INTERPRETATIONAL model in Baroque music (based on French Suite in D minor by J. S. Bach)

Background. For anyone creating his own interpretational version of a work which belongs to Baroque culture it is highly important to understand semantics of a given key, which in this day and age becomes a valuable asset to reveal the composer’s intention, including the works like French Suite in D minor by J. S.Bach. The approach, suggested in the article, elaborates existing studies, providing them with new meaning. The aim of the article is to reveal the significance of a key in the Baroque music, particularly in J. S. Bach’s works, as a premise for present-day musicians creating new versions of performance. Methodology of a research is founded on historically-theoretical and interpretational methods of analysis. Results. The genre of a keyboard suite holds an important place in J. S. Bach’s legacy. French Suite in D minor is the first one among others. Allemande is written in accordance with the customs of their time. At the same time, tonal development of each movement reflects general aesthetic principles of movement, realizing pivotal idea of the genre. The change in tonal reference points, which happens in the frameworks of Tonic – Dominant relations, shows diverse colours and tension of the development within one key. Allemande’s harmonic complexity exposes semantical sense of the key, which influences other dances. Sarabande is presented as a concentration of ‘funebre’ lyricism, the sense of Gigue is reconstructed due to the change of expected time signature 3/8 to 4/4 and usage of pulsating dotted notes. Courante and two Menuettos are marked by a certain simplicity and “transfiguration” of musical language, which causes not only a genre, but also imagery and semantical contrast. French Suite in D minor is a relatively difficult material for creation of performer’s interpretation. Contrasts of tempo and mood of the dances typical for this genre are not so obvious in this suite as compared to other J. S. Bach’s suites in minor keys. General atmosphere of reserve and inner tension is stressed by the key of D minor, which shapes the whole cycle’s character. Conclusions. The above mentioned peculiarities of J. S. Bach’s French Suite in D minor define the performance interpretation, designed to reveal dialectic unity of opposites in compositionally-dramaturgical structure of the Suite. The performer chooses means, aimed both at creation of macro-unity and at reveal of typological features of the suite genre which is based on contrast. One of the main factors contributing to unity is tempo of performance: apart from quite similar tempos of Allemande and Courante, Gigue is noteworthy, too, as its tempo due to peculiarity of melody and pathos, uncommon for the genre, is “decelerated” in a natural way. Suite contrast can be revealed through articulation and touche, as well as through tempo in view of singularity of Sarabande. Basing on the piece under analysis, we may state that in Baroque era D minor key was already interpreted as a bearer of complex and profound meaning, devoid of mundane, as a subjective key, retaining, however, possibility to be used to reveal objective generalising senses. Thus, we think it should be a “zone of special attention” for performers.

Dreaming in Motion: Zoom Excerpts from Black Motion Pictures

Abstract Gabrielle Civil, a Black feminist performance artist, and Anna Martine Whitehead, a Black transdisciplinary artist, formulate, exchange, and respond to embodied strategies of creativity and resistance. They discuss Black performance dreams and their own movements as Black performers. Recorded on June 4, 2020, during the coronavirus shutdown and shortly after George Floyd’s tragic death, their words have become a time capsule. Their conversation is part of Black Motion Pictures, Civil’s interview series with radical Black creatives on Zoom, an internet video conference platform. Time signatures and ellipses from the original Zoom transcript highlight the glitchy strangeness and mediation of the moment.

The Eschatological Key

Abstract In the first volume of his systemic series, German theologian Jürgen Moltmann begins his systematics with a musical metaphor; “The eschatological is not one element of Christianity, but it is the medium of Christian faith as such, the key in which everything is set …” Moltmann then goes on to propose that the eschaton is a temporal event, which breaks the logic of his initial metaphor of the key signature. This essay will explore the differences between understanding the eschaton explicated as the key that Christian hope is set as opposed to a temporal alternative, such as the time signature. Jeremy Begbie is brought into the conversation to explicate how “harmony” can guide our conversation of music theory, and Miguel De La Torre illuminates how Moltmann’s claim, which while revolutionary in many aspects, continues to rely on Eurocentric understanding of salvation history, just as music theory tends towards Eurocentrism. We also examine what we lose out on when we leave this uninterrogated. To conclude, we explore how Moltmann’s proposal about Christian hope becomes more coherent within the metaphor of key signature and right relationship instead of time signature and temporality.

Time Signature Detection: A Survey.

This paper presents a thorough review of methods used in various research articles published in the field of time signature estimation and detection from 2003 to the present. The purpose of this review is to investigate the effectiveness of these methods and how they perform on different types of input signals (audio and MIDI). The results of the research have been divided into two categories: classical and deep learning techniques, and are summarized in order to make suggestions for future study. More than 110 publications from top journals and conferences written in English were reviewed, and each of the research selected was fully examined to demonstrate the feasibility of the approach used, the dataset, and accuracy obtained. Results of the studies analyzed show that, in general, the process of time signature estimation is a difficult one. However, the success of this research area could be an added advantage in a broader area of music genre classification using deep learning techniques. Suggestions for improved estimates and future research projects are also discussed.

RETRACTED: Steal like an artist: Connection between critical thinking and creativity of a future musician in a digital environment

• Correlation between critical thinking and creativity in music was investigated. • The level of critical thinking was assessed using the Watson-Glaser test. • Respondents with a high level of critical thinking had a higher level of creativity. In the modern world, it is quite difficult to create authentic, unlike anything musical works, since there is a huge amount of different music. For this reason, it is extremely difficult to create a new product. The problem of creativity in this matter is of relevance. Although most studies on this topic show a positive correlation between critical and creative thinking in an online environment, there are a number of studies in which this correlation has not been traced. This fact is the rationale for this study. For this reason, this topic should be explored in more detail. As part of this work, the correlation between critical thinking and creativity in music production will be investigated (in this study, the correlation is proved by confirming the alternative hypothesis of the difference in students’ creativity depending on their critical thinking level). The sample of research participants was composed of 563 students. In the first stage, the level of critical thinking was assessed using the Watson-Glaser test. The respondents taking part in the experiment studied in music universities in the specialties of composing and arrangement. During the experiment, three groups were formed: respondents with a low level of critical thinking (first group), respondents with an average level of critical thinking (second group), and respondents with a high level of critical thinking (third group). At the second stage, the respondents were required to write a series of small pieces (30 measures with ¾ time signature (waltzes in major and minor)). The resulting compositions were evaluated by professors from various universities in China to determine the creativity in writing melodies. The obtained results, analyzed using Student's two-sample test for independent variables, showed that respondents with a high level of critical thinking had a higher level of creativity (about 80% or more) in a total digital environment, while respondents with an average and low level of critical thinking received almost equally low results (on average, not exceeding 60%, but in some cases, the results were slightly higher). In this case, the alternative hypothesis H 1 t about existence of investigated correlation was confirmed. It should be noted that the concepts of “creativity” and “authenticity” are abstract and rather subjective. Given the complexity of evaluating works from this point of view, teachers passed an oral survey in which they were required to define the word “creativity”. As the results showed, this task was difficult for most teachers, but they coped with it quite successfully. Most of the teachers gave the epithet “unlike anything” or “special”. All data sets were checked on obeying normal distribution using the Shapiro–Wilk test.

A New Variant of the Winternitz One Time Signature Based on Graded Encoding Schemes

Digital signature schemes are used to guarantee for non-repudiation and authenticity of any kind of data like documents, messages or software. The Winternitz one-time signature (WOTS) scheme, which can be described using a certain number of so-called “function chains”, plays an important role in the design of both stateless and stateful many-time signature schemes. The main idea of WOTS scheme is the use of a limited number of function chains, all of which begin at some random values. This work introduces WOTS-GES, a new WOTS type signature scheme in which the need for computing all of the intermediate values of the chains is eliminated. More precisely, to compute each algorithm of the proposed scheme, we only need to calculate one intermediate value. This significantly reduces the number of required operations needed to calculate the algorithms of WOTS-GES. To achieve this results, we have used the concept of “leveled” multilinear maps which is alsoreferred to as graded encoding schemes. We expect these results to increase the efficiency of Winternitz based digital signature schemes.

Effect of the second invariant of the Cauchy–Green deformation tensor on the local dynamics of dielectric elastomers

This paper aims to investigate the local oscillations of a dielectric elastomer with emphasis on the effect of the second invariant of the deformation tensor in finite strain theory on such oscillations. Four hyperelastic constitutive models are utilized in this study, namely the classic Gent model, a modified Gent model, a modified version of the Pucci–Saccomandi model, and the Mooney–Rivlin model. We derive the governing equations for all the models through the use of the Euler–Lagrange formulation. We explore the local responses of the system in the framework of the nonlinear frequency responses by solving the equations of motion using the multiple time scales method. In addition, to provide an in-depth analysis, we analyze static and dynamic electromechanical instabilities by plotting the voltage-stretch diagram and the time signature. The numerical results for damped and undamped dielectric elastomers are simulated and compared. We analyze the system’s response for the aforementioned hyperelastic constitutive functions, and compare the differences and similarities of models. Based on the results, two saddle–node bifurcations occur in the system. Generally, increasing the second invariant parameters of the hyperelastic models, decreases the response amplitude. As contribution of the second invariant in the Mooney–Rivlin model is increased, for both damped and undamped systems, softening turns into hardening nonlinearity. We also show that the second invariant tunes the bifurcation points and instability of the system. Moreover, it can control the static and dynamic pull-in and snap-through voltages.

Interrogating the mechanism of the solvation dynamics in BmimBF4/PC mixtures: A cooperative study employing time-resolved fluorescence and molecular dynamics

In this article, the solvation in ionic liquid/molecular solvent (IL/MS) mixtures is investigated. The steady-state and time-resolved measurements of the solvation of coumarin 153 (C153) in BmimBF4/propylene carbonate are presented. A slight bathochromic shift was observed in the steady-state spectra upon increasing the IL molar fraction xIL. The time correlated photon counting TCSPC and fluorescence upconversion techniques were used to obtain the experimental solvation response functions (SRFs). The SRFs were found to be multi-exponential and the average solvation times increased with xIL. The MD simulations were performed to help the interpretation of the experimental data. An unprecedentedly good agreement between the measured and the calculated SRFs was achieved. The partition of the coulombic energy of interaction between the atoms of C153 and cations, anions and PC molecules provides a deep understanding of the time signatures of the mixture components participation in the solvation response. Indeed, the slow portion of the SRFs was found to be dominated by the IL. These time signatures change in function of xIL and represent the previously established regimes of IL/MS mixtures: electrolyte solution (xIL< 0.2) and lubricated IL (xIL> 0.2). These results will be of crucial interest for the understanding of the molecular rearrangements occurring in IL/MS electrolyte models for dye sensitized solar cells (DSSCs) after photo-excitation.

Shifts in Gait Signatures Mark the End of Lifespan in Mice, With Sex Differences in Timing.

Reduced walking speed is a hallmark of functional decline in aging across species. An age-related change in walking style may represent an additional key marker signifying deterioration of the nervous system. Due to the speed dependence of gait metrics combined with slowing of gait during aging, it has been challenging to determine whether changes in gait metrics represent a change in style. In this longitudinal study we employed gait signatures to separate changes in walking style and speed in mice. We compared gait signatures at mature adult age with middle aged, old and geriatric time points and included female and male sub-cohorts to examine sex differences in nature or timing signature shifts. To determine whether gait signature shifts occurred independently from a decline in other mobility domains we measured balance and locomotor activity. We found that walking speed declined early, whereas gait signatures shifted very late during the aging process. Shifts represented longer swing time and stride length than expected for speed, as in slow motion, and were preceded by a decline in other mobility domains. The pattern of shifts was similar between female and male cohorts, but with sex differences in timing. We conclude that changes in walking style, speed and other mobility domains represent separate age-related phenomena. These findings call for careful, sex specific selection of type and timing of outcome measures in mechanistic or interventional studies. The pattern of age-related gait signature shifts is distinct from patterns seen in neurodegenerative conditions and may be a translatable marker for the end of the lifespan.