Materiality , Language and the Production of Knowledge Art , Subjectivity and Indigenous Ontology

Since all theories of knowing deal with the being of subjects, objects, instruments and environments, they can be viewed as onto-epistemological.  This chapter examines key ideas that emerge from the work of Julia Kristeva – 'the speaking subject', 'materiality of language' and 'heterogeneity' – to demonstrate  how ontology and epistemology are inextricably entwined in knowledge production. Kristeva also affirms both the agency of matter and  the dimension of human/subjective agency implicated in cultural production. This is contrasted with Gilles Deleuze and Felix Guattari’s account creative practice. The article also draws on the artistic work of researcher-practitioner Brian Martin, and his account of the relationship between Indigenous Australian art and culture to demonstrate that in an Indigenous world view, the real, the immaterial, the imaginary and the representational occur concurrently.

Australian Indigenous ontology and art by Brian Martin. 2 In weaving together some of the conceptual threads that emerge from these domains of thought, I hope to illuminate the relationship between being and knowing as living process.It is this notion of sentience, one that acknowledges the distinction between the organic and the inorganic 'meat' and the living body as the site of the production of meaning, which articulates the divergence in the materialist perspectives of these two bodies of thought.This divergence can be traced to the different genealogies of the ideas of Kristeva and of Deleuze and Guattari.
A crucial difference between Kristeva's and Deleuze's accounts of creative production and transformation is the notion of dialectics.Kristeva recasts and overturns the Hegelian dialectic, which is based on a triadic struggle and the projection or movement towards transcendence, and recasts Hegel's conception of 'negativity' as the drive towards true knowledge or totality.Kristevan 'negativity' points to the material (and therefore unconscious) dimension of our encounter with language in creative production and revolution.Operating dynamically and dialectically between the biological and social order, it ruptures the fixed categories and oppositions of language to produce not totality, but what Kristeva refers to as an 'infinitesimal differentiation within the phenotext'. 3Kristeva highlights the way art becomes a potent vehicle for articulating a dissenting subjectivity.The speaking subject is the split subject divided between conscious and unconscious motivations-between physiological processes and social constraints.Her notion of negativity is founded on the dialogic and heterogeneous dimensions through which the subject and language operate.In Kristevan thought, heterogeneity implies a relationality that affirms difference, in that it is both material/biological and semiotic.This material--semiotic (pace Haraway) affirms a radical immanence that is, at the same time, situated. 4Hence Kristeva's account of aesthetic experience as revolution articulates a second overturning (after Karl Marx) of Hegel's dialectic that posits social and political struggle in terms of thesis, antithesis and synthesis.
Hegel's notion of dialectics puts consciousness first.Marx's, on the other hand, emphasises the means of economic production and its inherent contradictions as a basis for dialectical development.The contradiction inherent in all things perpetuates the dialectic process and results in a cleavage, a struggle between the two elements of the contradiction that results in the elimination of the weaker element.According to Kristeva, art replaces economic materiality, and its underlying implication of transcendence, with biological process and aesthetics.For Kristeva, there is no essential separation between body and mind.Biology-the rhythms and drives operating through the body as instinctual responsiveness to objects in the world (the semiotic) is crucial to, and part of, our signifying processes.Aesthetic experience implies a heterogeneous sentient and relational subject-one that is, at the same time, constituted through material biological processes and language.
Transformations that occur in subjectivity can thus be understood as causal and situated.They result in transformations of language and have the potential to transform discourse, because the subject is not only material process but is also in and of language.By turning inward to the material processes of subjectivity, Kristeva's notion of practice and dialectics goes beyond a view of contradiction that involves a replacement of one contradiction or thesis with another.Her view of dialectics originates in the work of René Thom and is grounded on the theory of catastrophe-the idea that small changes and contradictions in minor parts of a non--linear system or field of forces can cause instabilities of attraction and repulsion that may lead to sudden changes in the whole system.In this model, when elements in the system lose equilibrium or are shattered, one element does not replace another, but shattered elements reform to bring about a completely new (but nevertheless heterogeneous) system or object.As will be discussed later in this essay, Kristeva's elaboration of the chora and of pre--Oedipal process provides an explanation of the co--constitutive relationship between meaning and matter in processes that are laid down prior to the subject's entry into language; such processes illuminate the notion of the subject as a 'filter' through which the world is transformed into language and thought.This aspect of her thought also deviates from Deleuze and Guattari's conceptions of 'affect' and the 'body without organs'.
Deleuze's anti--Hegelianism originates in Nietzsche's notion of genealogy and the will to power underpinned by a focus on the productivity of the nondialectical differential forces.'Let us recall Nietzsche's idea of the eternal return a little ditty, a refrain, but which captures the mute and unthinkable forces of the Cosmos.' 5 Immanence, virtuality, forces, speed, movement and genesis, rather than dialectics, are key concepts underpinning Deleuze and Guattari's account of production and transformation.In its movement towards becoming, 'the body is also mere body, just matter under the pulsation of cosmic forces, the same that moves dust and planets in the universe'. 6Arthur Kroker also illuminates the tendency in Deleuze and Guattari to abstract the body, reducing it to inorganic matter.He observes that to enter the body of their texts is to 'experience a fantastic psychological curvature of the dematerialization and decontextualization of one's own missing body'. 7Through insistence on notions of forces and intensities and the machinic 'body without organs' in Deleuze and Guattari's account of cultural production, the specific relational heterogeneity of carnal materiality is elided-movement or capture occurs outside.This tendency is evident in Deleuze's Francis Bacon: The Logic of Sensation, where the focus remains predominantly on the external object and the 'rhythmic unity of the senses can be discovered only by going beyond the organism'. 8 What is Philosophy?Deleuze and Guattari put forward a materialist conception of knowledge production, which they describe as 'the art of forming, inventing and fabricating concepts'. 9However, while they do acknowledge the implication of the human subject through their notion of conceptual personae, they do not fully elucidate the crucial relationship between biology, matter and language that gives rise to semiosis as an ineluctable foundation of onto--epistemology.
Kristevan thought provides a model for understanding how material--discursive practices emerge from corporeal responses and are translated into language and thought.In experience--in--practice there is a constant movement between the material world, the rhythmic unity biological/material self (the self as 'other') and the social self.This movement instantiates a performative production of knowledge or onto--epistemology.
'Permeability' is a useful term for unravelling Kristeva's account of the complex relationship between body and mind and individual and society as a dynamic process of how we come to make meaning.It allows us to understand that humans are continuous with nature and other objects in the world.Biological processes that support and enable human life operate as a semiotic 'filter' and this filtering attributes value to objects encountered via sensation and affect.Through her conception of the chora, and of the relationship between the infant and the mother's body, Kristeva demonstrates that human consciousness and language are products of these 'filtering' processes.
A crucial distinction between Kristeva's and Deleuze and Guattari's accounts can be found in their differing conceptions of 'affect' and the emphasis that Kristeva places on the link between affect and language.Affect is hardwired into the human biological system as an instinctual mechanism for warding off-impelling the organism away from-what is sensed as dangerous and harmful and for registering pleasurable sensations.In departing from Freud, Kristeva suggests that both negative and positive affect have the power to impel; both can therefore be understood as a form of agency.It is in the phase where pleasure or un--pleasure is registered that objects begin to take on value or become perceptions as opposed to what Deleuze and Guattari call 'percepts' or sensations that are 'independent of a state of those who experience them'. 10leuze and Guattari conceive affects as non--human becomings or blocs of sensation that occur when material passes into sensation.They explain that this takes place within a zone or phase of indetermination and indiscernibility that immediately precedes natural differentiation.In this framework affects are non-human compounds of sensation that occur when humans become continuous with the material world.When sensation becomes sensation of a concept, the composite sensation is reterritorialised. 11Deleuze and Guattari's account of these human/non-human transformations is ambiguous and couched in abstractions that do not fully explain the movement from the material process (blocs of undifferentiated sensation as being) to the subject of language and thought.Kristeva's notion of heterogeneity, on the other hand, precludes the conception of pure or undifferentiated sensation of (human) beings.Central to understanding this and how being and language co--emerge is what Kristeva has theorised as the semiotic chora that gives rise to the heterogeneity of language: the 'symbolic'-language as it signifies (the communicative function of language)-and the 'semiotic' language as it is related to the material or biological processes closely implicated in affect. 12

-THE SEMIOTIC AND THE SYMBOLIC
The semiotic chora, the space or site of biological interactions and exchanges between the infant and the mother's body, registers the first imprints of experience that are rudimentary signals of language that will follow.It is an articulation of bodily drives, energy charges and psychical marks-a non--expressive totality, known through its effects.This constitutes the heterogeneity that distinguishes human biology and psychic life from the outset.It is also related to the dynamism of the body constantly in motion and perpetually seeking to maximise the capacities of the living organism.It is a complex of pulsations-intensities, tensions and release of tensions that occur through interactions with what lies beyond or outside the living system.Kristeva tells us that operations of the chora organise pre--verbal psychic space according to logical categories that precede and transcend language.These operations or semiotic functions, which are constituted through biological drives and energy discharges, initially oriented around the mother's body, persist as an asymbolic modality that governs the connections between the body and the 'other' throughout the life of the subject.They articulate a continuum between the body and external objects and between the body and language. 13We may now understand the 'semiotic' as an alternative material 'code' of language, a 'bodily knowing' that nonetheless implicates itself in relays of meaning that are manifested in social relations.
In creative production, entanglements or enfoldments between the body and objects give rise to drives or impulses that are articulated by the semiotic and result in variations and multiplicity of meanings that may be produced.The semiotic disposition of language, which corresponds to what Deleuze and Guattari describe as harmonies, rhythms or style, establishes a relational functioning between the signifying code and the fragmented or drive--ridden body of the speaking (and hearing/seeing) subject. 14This putting--into--process of language must connect with our biological processes, affects and feelings in a vital way if language is to take on particular meanings or to affect us.Creative practice or 'the productive performance' of language maintains the link between the semiotic and the symbolic, between discourse and our lived and situated experiences-our material being in the world-because unlike Deleuze and Guttari's body without organs, the body in Kristeva's articulation of practice is always already heterogeneously constituted.Three terms, 'negativity', 'rejection' and 'signifiance' are crucial to understanding Kristeva's account of language as material process that is predicated on relationality.
-NEGATIVITY AND REJECTION 'Negativity' can be understood as the processes of semiotic motility and charges or 'death drive', a force that impels movement towards an undifferentiated or archaic phase that precedes the subject's entry into language.Kristeva draws on Freud to explain negativity as a drive or urge, inherent in organic life to return to earlier states. 15Negativity operates dynamically and dialectically between the biological and social order, replacing the fixed categories and oppositions of language to produce what Kristeva refers to as an 'infinitesimal differentiation within the phenotext'. 16gativity is closely related to, and cannot be considered apart from, two related concepts in Kristeva's account of language as material process.She posits 'expenditure' or 'rejection' as better terms for explaining the movement of material contradictions that generate the semiotic function.If negativity is a motility or dynamism that seeks an undifferentiated state, rejection is what repeatedly interrupts this movement.Rejection moves between the two poles of drives and consciousness.Think of negativity and rejection working together as a kind of pre-linguistic pulse that sets up a constant rhythmic responsiveness to language and to other objects in the world.Rejection constitutes the shattering of unity or unified meaning.It has a relation or connection to language, but only in terms of what Kristeva refers to as scission or separation that opens up a crucible of intensities and sensation where meaning is ruptured, superseded and exceeded. 17This is an indication of the asymbolic functioning of the chora as discussed above.However, rejection is ambiguous in that it is also a precondition for the emergence of new meanings and renewed or recuperated subjectivity.The perpetual rhythms and workings of material and biological processes that maintain the living organismnegativity-rejection … negativity-rejection-are continuous with processes that produce the subject, language and meaning.They begin the process of 'filtering' that transforms stimuli into coherent form.What is important to note at this stage, is that in aesthetic experience both the production and reception of the artwork inscribes negativity and rejection by bringing the symbolic function into an encounter with the semiotic or material dimensions of the work.This results in an unsettling and multiplying of meaning, and the work is experienced both as material object and as a form of representation, as will be illustrated with reference to the work of Brian Martin.The ongoing renewal and production of the subject or subjectivity through material processes underpins the ongoing renewal and production of language and meaning in creative practice as onto--epistemology.

-SIGNIFIANCE
The term signifiance distinguishes the supplementary signifying process that operates beyond established codes from signification-the conventional way in which words signify meaning. 18Signifiance is an alternative signifying process, the result of the heterogeneous workings of language which articulates both symbolic and semiotic dispositions: language as it is conventionally coded as opposed to material/sensory articulations of language-sound, rhythm and prosody in verbal language; colour, line and other formal elements in visual language.This double articulation of language allows the text or artwork that emerges from experience--in-practice, to signify what the communicative or representative function of the work cannot say. 19Signifiance allows us to grasp how words or verbal and visual utterances can be charged with multiple and hitherto unimagined meanings.In Edvard Munch's (1893) painting The Scream for example, this relationship becomes apparent.The unity of the composition is constantly disrupted by the impact of lines creating dynamism and movement and breaking up the compositional space.
Ambiguity and indeterminacy give rise to multiple meanings-for example, it is difficult to distinguish landscape from sky or to tell if the two figures in the background are approaching or receding; if viewing is sustained over a longer period of time, the retinal impact of colour and line in this painting operate synaesthetically to become 'noise' and the surface of the painting induces not meaning but sensation.Thus we can demonstrate that the semiotic, as well as being a precondition for the symbolic, also functions synchronically with the symbolic.The marks, swirling lines and brushstrokes in Munch's painting both indicate and exceed their representational and compositional functions.Sensation, language and thought become concurrent and interchangeable and the boundaries between them are permeable.The work captures the artist's particular lived and embodied experience and preserves it in what Deleuze and Guattari describe as a 'bloc of sensation'. 20The work is not only a representation of the scream, it is the scream as sensation: these two elements affect the viewer simultaneously.
In Deleuze and Guattari's schema such a work would give rise to percepts and affects that engender a non--human becoming, where being and the world merge as material process.How can we explain this erasure of the subject and emanation of the work of art without falling into mysticism?Kristevan psychoanalysis provides us with a way out of the impasse through its account of the relationship between biological processes and thought/language.In a sense, psychoanalysis gestures towards notions of a 'transcendental' that neither privileges the Cartesian subject nor social constructivist accounts of the subject.Kristevan thought, with its insistence on heterogeneity, does not fully jettison the human or subjective dimension of this process because in Kristeva's framework the subject as sensation, as sentient being, is also an already (relationally) constituted and heterogeneous entity.
It has perhaps become clear from the discussion so far that words and images impinge on the body in the same way as objects.Deleuze and Guattari acknowledge that philosophical concepts are sensibilia in the same way that aesthetic objects are sensibilia. 21Aesthetic experience also corresponds with what they describe as the moment material passes into sensation and articulates a zone where we no longer know which is animal and which is human. 22What Kristeva provides, however, is an understanding of the originary processes that link bodily processes to language.This is fundamental to grasping the idea of creative production as material process and as an alternative mode of semiosis.
In Art beyond Representation, Barbara Bolt illustrates this with her description of experience--in--practice as 'working hot'. 23In material practices such as painting, there is an intensification of contradiction brought about by the unpredictable and/or accidental effects produced by the interactions of the materials and tools used in the making of the work.Often, this requires speedy and spontaneous responses which leave no time or space for rational thought.This does not mean, as Deleuze and Guattari imply and as Judith Butler has claimed in her notion of performativity, that the subject is, strictly speaking, absent. 24The issue of the subject's absence in performativity turns on the relationship between the notion of an already constituted subject of language/discourse and the subject of practicethe subject as being.
In Revolution in Poetic Language, Kristeva tells us that 'the subject never is, the subject is only the signifying process and he appears only as a signifying practice'. 25It is important not to mistake the inflection in Kristeva's statement since it does not imply the total absence of the subject, but a movement towards, and appearance of, the subject to a more fluid and dynamic process.Elsewhere, Kristeva's references to the absence of the (human) subject relate to psychoanalytical accounts (particularly those of Lacan)-of the subject as it is positioned or coalesced through the symbolic and the social.In her theorisation of creative practice, however, Kristeva's notion of the 'speaking subject' goes beyond such accounts by positing heterogeneity.This casts a different light on Deleuze and Guattari's notion of 'sensation as being' and on their description of affects as 'non--human becomings' of man. 26The notion of heterogeneity acknowledges another register or prevailing presence of 'subjectivity' as material process and contradiction that constitute different forms of agency.The experience of practice puts the subject in 'process/on trial', a condition in which subjective processes are predominantly determined by biological processes and drives so that an alternative logic is at work; the logic of material process and of the unconscious where there is 'no time' in the sense of linear temporality, and where the binaries and contradictions of the symbolic and established discourses do not hold.The knowledge or reality brought about by direct experience is thus a signifying apprehension of a new heterogeneous object. 27Hence the 'subject' can be understood as a filter or passageway where there is a struggle between conflicting tendencies or drives whose stases or representamen are rooted in affective processes.This point is crucial to understanding why and how Kristeva places the subject and forms of subjective agency, rather than mechanistic or automatic processes, at the core of revolutionary practice.The key is her conception of 'affect' as both positive and negative affects that originate in pleasure and displeasure.
Pleasure can be understood as the removal or absence of displeasure.In encounters with objects in the world, negativity and rejection give rise to sensation.However, following raw sensation is a concurrent emergence or registering of positive or negative affects that attribute value(s) or that 'colour' encounters with the material world and other sensibilia.This constitutes a movement towards thought and symbolic language.The question of just how this shift occurs still remains.
The psychoanalytical term 'cathexis' is pertinent here.Synonymous with 'investment', cathexis is a drive that produces subjective motivation or volition towards both libidinal and discursive economies.Charles Rycroft describes it as 'a quantity of energy attaching to any object or mental structure'. 28'Hypercathexis' involves an intensity of investment in one process or set of configurations in order to repress others. 29Cathexis is a moment of the coalescing of subjectivity according to the pleasures and displeasures of our encounters with objects-something between an emotional commitment and a vested interest in the relative rewards and satisfactions offered in processes of making and interpreting art and indeed in experiences of everyday life.The notion of cathexis permits an understanding of movements between being and knowing or the culminating point that Deleuze and Guattari call 'reterritorialisation'. 30 From this we may argue for a materialist 'transcendental'; material process as an infinite unfolding or two--way movement between the material world, biological processes and discourse.The subject as biological organism, or being, is a 'filter' through which objects pass as raw sensation and are then 'transubstantiated' into language.In experience--in--practice language becomes the space of an alternative or translinguistic representation that allows a transfer from instinctual conflict arising from the physiological on one hand, and conscious thought on the other.Situated between the body (energy, drive, excitability) and mind (representation), 'language allows thought to reach and stabilise energy'. 31e focus on subjective processes as forms of agency must also be understood in relation to the 'agency' of materiality itself.Kristeva's work acknowledges the agency of 'brute' materiality.In her account there is no opposition between inside and outside-consciousness and materiality are mutually constitutive and enfolded.This is the basis of onto--epistemological practice and it is in this sense that we can begin to articulate what we mean by the notion of a 'new materialism'.

-INDIGENOUS ONTOLOGY
The notion of 'onto--epistemology' as the basis of all cultural production is articulated in Australian artist Brian Martin's practice and his account of Australian Indigenous ontology.Martin tells us that in an Indigenous worldview it is self-evident that the immaterial and the imaginary, the real and representation, occur interchangeably and concurrently.Through his art practice and elaboration of what he calls 'real immateriality', Martin brings a fresh perspective to understanding the movements that occur between the material world, being and knowing.
The relationship of culture and 'land' or 'Country' is the foundation of Indigenous ideology and culture.In a traditional Aboriginal society, movement with and in Country defines material existence as ways of being, ways of doing and ways of knowing.This relationship constitutes and is constituted by the interconnection of memory, life and culture, which are embedded in Country: Indigenous art practices manifest this trinity.Within this framework, the immaterial is materially constituted by the real material conditions of existence, where the immaterial itself, becomes a reality.This 'immateriality' in Indigenous cultural ideology is manifest in the real existence of Country and ever continuing cultural practices. 32e interrelatedness of material existence and cultural production challenges dominant Western discourse and conceptions of art formulated in a representationalist view of the world.The ontological relationship that people have to Country is vital in Indigenous cultural practices where the relationship between the referent and the sign is causal and reciprocal.Indigenous ontology and cultural practices are based on a methexical relationship, or what Paul Carter describes as a performative action that brings something into being and existence. 33For example, when the emu dance is performed, the being of sensation of the dancer is emu and the aesthetic image produced transfers the sensation of the dancer's lived experience to the audience.Pertinent here is Deleuze and Guattari's notion of the artwork as 'monument'.The artwork as monument does not commemorate the past, but is a bloc of present sensations. 34In this example it engenders a becoming emu of both the dancer and the audience.Martin observes that this methexical relationship, which entails a collapse between the ontological and the representational, emphasises the physical/material ground of Indigenous practices and permits an understanding of how the 'real' and the 'immaterial', the 'imaginary', the 'spiritual' and the 'representational' operate concurrently as 'real immateriality'.It is this interrelatedness and its effects that assign value and meaning in Indigenous cultural production and worldview.
In Indigenous culture there is also no distinction between art, culture and living or being.In Aboriginal languages words used about art are not nouns, but denote action.The artwork enacts the thing so that a painted landscape, tree or animal is the thing itself.Making and viewing artworks involves a re--experiencing of the thing.
As Martin explains in his analysis of the works of Kathleen Petyarre, Margaret Petyarre and Badger Bates in 'Immaterial Land', the function of the repetition of mark--making in Aboriginal art is to engender a performative methexical mapping of Country, to bring Country into being. 35Martin explains that we see this again in Rover Thomas's 1984 painting Landscapes, where the dots become an indexical trace of the jabbing action of painting that maps the ground and produces a synesthetic rhythm conveying a sense of movement.This allows the maker to re-experience Country and viewer to grasp how both meaning and re--experiencing emerges from the action of art making.This double articulation can be better grasped through a closer examination of the terms 'cathexis' and 'methexis' as they are explicated by Kristeva via Freud, and Carter in his work The Lie of the Land. 36In elaborating the emergence of revolutionary discourse, Kristeva draws on Freud's account of 'cathexis', as discussed above, as a term to describe the quantity of drive or libidinal energy attaching to, or invested in, an object, representation or mental structure.A build up of cathexis can lead to sublimation and the formation of images that are affectively charged.Hence cathexis can be understood as an aspect of internal psychic processes that lead to creative production.
Methexis on the other hand, refers initially to external practices-the participation in performative ritual or memorialisation.Paul Carter describes this as 'a reverent miming that involves the feeling of certain emotions, allowing one to get into a certain frame of mind or a state of "passionate sympathetic contemplation"'. 37 this notion of performance there is no dichotomy between actor and an object to be acted upon, but the two come into being through each other. 38Hence, we may conceive of methexis as an external action or performative participation that gives rise to internal processes, which, in turn, lead to creative production.Further, we can argue that methexis is a mode of being--in--practice that gives rise to certain cathexes through which aesthetic images emerge.It should be noted that this conception of methexis goes beyond that of mimesis as imitation.Rather, it may be understood as the 'inhabiting' or repetition of language that allows forms to be VOLUME21 NUMBER2 SEP2015 114 apprehended anew or as if experiencing them in 'the real' and/or for the first time.
This notion of methexis allows us to appreciate virtuosity in the performance of a previously composed work, such as a piece of music, as creative production in its own right.
In Martin's drawing practice the interrelationship between figuration and abstraction not only enacts this methexical dimension of art making, but also mirrors the interrelationship between the material and the immaterial, the imaginary and the real.This is achieved through the articulation of the relationship between the abstract and the representational.In his Methexical Countryscapes (see, for example, Figure 1), the rhythm of marks made using charcoal on paper maps the texture of Country as the artist has experienced it.
The scale of Martin's works (2 metres by 1.5 metres) heighten their immersive quality.However, it is Martin's use of the grid (each work is made up of thirty panels) that articulates the relationship between abstraction and figuration and hence the notion of the concurrence of representation and the real or material in aesthetic experience.

Figure 2 :
Figure 2: Brian Martin, Darug 1, 2013, single panel, charcoal on paper, 210 x 297 mm (detail); courtesy Brian Martin Part of this essay appeared in a different form in Estelle Barrett, Kristeva Reframed: Interpreting Key Thinkers for the Arts, I.B.Tauris, London, 2011.I am grateful to the publishers for allowing me to republish it.I would also like to thank Brian Martin for allowing me to reproduce his images here.Gilles Deleuze, and Félix Guattari, What is Philosophy?, trans.Hugh Tomlinson and Graham Burchill, Verso, London and New York, 1994; Julia Kristeva, Revolution in Poetic Language, trans.Margaret Waller, intro.Leon S. Roudiez, Columbia University Press, New York and Oxford, 1984. -ACKNOWLEDGEMENTS1