Статті в журналах з теми "Moment angulaire orbital des quarks"

The paper focuses on considering some special precessional motions as the spin motions, separating the octonion angular momentum of a proton into six components, elucidating the proton angular momentum in the proton spin puzzle, especially the proton spin, decomposition, quarks and gluons, and polarization and so forth. Maxwell was the first to use the quaternions to study the electromagnetic fields. Subsequently the complex octonions are utilized to depict the electromagnetic field, gravitational field, and quantum mechanics and so forth. In the complex octonion space, the precessional equilibrium equation infers the angular velocity of precession. The external electromagnetic strength may induce a new precessional motion, generating a new term of angular momentum, even if the orbital angular momentum is zero. This new term of angular momentum can be regarded as the spin angular momentum, and its angular velocity of precession is different from the angular velocity of revolution. The study reveals that the angular momentum of the proton must be separated into more components than ever before. In the proton spin puzzle, the orbital angular momentum and magnetic dipole moment are independent of each other, and they should be measured and calculated respectively.

We employ the polarized chiral constituent quarks to extract the polarized structure function of the nucleon. The polarized valon model is used to calculate the spin dependence of parton distribution functions of meson. The connection between the polarized structure of the proton and the Goldstone bosons, using the chiral quark model (χQM) is analyzed and the spin dependence of the parton distribution functions for pion and kaon, is obtained thoroughly. These functions are evolved to high Q2 values, using the singlet, nonsinglet and quark–gluon moments (ΔMS, ΔMNS, ΔMgq) which are convoluted with the polarized valon distributions. The polarized valon distributions for meson are computed, based on a phenomenological method and a comparison between polarized and unpolarized parton distribution functions for pion and kaon are performed. As a consequence of the χQM, the SU (3)f symmetry breaking for the spin dependent of the nucleon sea distributions is achieved. The required polarized parton distributions of the proton will be obtained from the parton distribution functions of the polarized meson via the related convolution integral which are existed in the χQM. Following that the analytical result for the proton's spin structure function, [Formula: see text], is obtained and compared with experimental data. Finally, the parton orbital angular momentum of meson are introduced and the total spin of the meson, based on this quantity and the first moment of distributions for gluon and singlet sectors, are obtained.

Analytical and numerical results, for the orbital and spin content carried by different quark flavors in the baryons, are given in the chiral quark model with symmetry breaking. The reduction of the quark spin, due to the spin dilution in the chiral splitting processes, is transferred into the orbital motion of quarks and antiquarks. The orbital angular momentum for each quark flavor in the proton as a function of the partition factor κ and the chiral splitting probability a is shown. The cancellation between the spin and orbital contributions in the spin sum rule and in the baryon magnetic moments is discussed.

An attempt to treat the asymptotic freedom and the quark confinement as a self-consistent problem in the framework of relativistic quantum mechanics is realized. It is shown that the confinement of quarks induces a change of their helicities together with a simultaneous alteration of orbital momenta, so that the total angular momentum of each quark is conserved. This observation may cast light on the so-called proton spin puzzle after some additional numerical estimations.

The proton spin puzzle issue focused the attention on the parton spin and orbital angular momentum contributions to the proton spin. However, a complete characterization of the proton spin structure requires also the knowledge of the parton spin-orbit correlation. We showed that this quantity can be expressed in terms of moments of measurable parton distributions. Using the available phenomenological information about the valence quarks, we concluded that this correlation is negative, meaning that the valence quark spin and kinetic orbital angular momentum are, in average, opposite. The quark spin-orbit correlation can also be expressed more intuitively in terms of relativistic phase-space distributions, which can be seen as the mother distributions of the standard generalized and transverse-momentum dependent parton distributions. We present here for the first time some examples of the general multipole decomposition of these phase-space distributions.

Is gauge-invariant complete decomposition of the nucleon spin possible? Although it is a difficult theoretical question which has not reached a complete consensus yet, a general agreement now is that there are at least two physically inequivalent gauge-invariant decompositions (I) and (II) of the nucleon. In these two decompositions, the intrinsic spin parts of quarks and gluons are just common. What discriminate these two decompositions are the orbital angular momentum parts. The orbital angular momenta of quarks and gluons appearing in the decomposition (I) are the so-called "mechanical" orbital angular momenta, while those appearing in the decomposition (II) are the generalized (gauge-invariant) "canonical" ones. By this reason, these decompositions are also called the "mechanical" and "canonical" decompositions of the nucleon spin, respectively. A crucially important question is which decomposition is more favorable from the observational viewpoint. The main objective of this concise review is to try to answer this question with careful consideration of recent intensive researches on this problem.

Un vortex optique est un faisceau laser dont le front d’onde est hélicoïdal. Il est donc chiral, d’hélicité gauche ou droite selon le sens de l’hélice. En plus du moment angulaire de spin qui correspond à la polarisation, les photons possèdent aussi un moment angulaire orbital (OAM) qui est quantifié et caractérise l'hélicité du vortex. L’interaction non linéaire de vortex optiques avec des atomes conduit à l’échange d’OAM avec l‘ensemble atomique et la génération de nouveaux vortex. Les propriétés quantiques de ces vortex sont une ressource exploitable dans le cadre des technologies quantiques comme le stockage et le codage de l’information.

The status of lattice calculations of the quark spin, the quark orbital angular momentum, the glue angular momentum and glue spin in the nucleon is summarized. The quark spin calculation is recently carried out from the anomalous Ward identity with chiral fermions and is found to be small mainly due to the large negative anomaly term which is believed to be the source of the ‘proton spin crisis’. We also present the first calculation of the glue spin at finite nucleon momenta.

The Hadronic Paschen-Back effect (HPBE) is a new phenomenon induced by the interplay between finite orbital angular momenta of hadrons and external strong magnetic fields. We review the HPBE in P-wave charmonia and show its mass spectra, deformed wave functions, and mixing ratios, which are evaluated by the constituent quark models in a magnetic field and the cylindrical Gaussian expansion method.

I describe a few of the most exciting open questions in high energy spin physics. After a brief look at (g - 2)μ and the muon electric dipole moment, I concentrate on QCD spin physics. Pressing questions include the interpretation of new asymmetries seen in semi-inclusive DIS, measuring the polarized gluon and quark transversity distributions in the nucleon, testing the DHGHY Sum Rule, measuring the orbital angular momentum in the nucleon, and many others which go beyond the space and time allotted for this talk.

A primary question in hadron physics is how the mass scale for hadrons consisting of light quarks, such as the proton, emerges from the QCD Lagrangian even in the limit of zero quark mass. If one requires the effective action which underlies the QCD Lagrangian to remain conformally invariant and extends the formalism of de Alfaro, Fubini and Furlan to light-front Hamiltonian theory, then a unique, color-confining potential with a mass parameter [Formula: see text] emerges. The actual value of the parameter [Formula: see text] is not set by the model – only ratios of hadron masses and other hadronic mass scales are predicted. The result is a nonperturbative, relativistic light-front quantum mechanical wave equation, the Light-Front Schrödinger Equation which incorporates color confinement and other essential spectroscopic and dynamical features of hadron physics, including a massless pion for zero quark mass and linear Regge trajectories with the identical slope in the radial quantum number [Formula: see text] and orbital angular momentum [Formula: see text]. The same light-front equations for mesons with spin [Formula: see text] also can be derived from the holographic mapping to QCD (3+1) at fixed light-front time from the soft-wall model modification of AdS5 space with a specific dilaton profile. Light-front holography thus provides a precise relation between the bound-state amplitudes in the fifth dimension of AdS space and the boost-invariant light-front wavefunctions describing the internal structure of hadrons in physical space-time. One can also extend the analysis to baryons using superconformal algebra – [Formula: see text] supersymmetric representations of the conformal group. The resulting fermionic LF bound-state equations predict striking similarities between the meson and baryon spectra. In fact, the holographic QCD light-front Hamiltonians for the states on the meson and baryon trajectories are identical if one shifts the internal angular momenta of the meson ([Formula: see text]) and baryon ([Formula: see text]) by one unit: [Formula: see text]. We also show how the mass scale [Formula: see text] underlying confinement and the masses of light-quark hadrons determines the scale [Formula: see text] controlling the evolution of the perturbative QCD coupling. The relation between scales is obtained by matching the nonperturbative dynamics, as described by an effective conformal theory mapped to the light-front and its embedding in AdS space, to the perturbative QCD regime. The data for the effective coupling defined from the Bjorken sum rule [Formula: see text] are remarkably consistent with the Gaussian form predicted by LF holographic QCD. The result is an effective coupling defined at all momenta. The predicted value [Formula: see text] is in agreement with the world average [Formula: see text]. We thus can connect [Formula: see text] to hadron masses. The analysis applies to any renormalization scheme.

Abstract We revisit the problem of the small Bjorken-x asymptotics of the quark and gluon orbital angular momentum (OAM) distributions in the proton utilizing the revised small-x helicity evolution derived recently in [1]. We relate the quark and gluon OAM distributions at small x to the polarized dipole amplitudes and their (first) impact-parameter moments. To obtain the OAM distributions, we derive novel small-x evolution equations for the impact-parameter moments of the polarized dipole amplitudes in the double-logarithmic approximation (summing powers of αs ln2(1/x) with αs the strong coupling constant). We solve these evolution equations numerically and extract the leading large-Nc, small-x asymptotics of the quark and gluon OAM distributions, which we determine to be$$ {L}_{q+\overline{q}}\left(x,{Q}^2\right)\sim {L}_G\left(x,{Q}^2\right)\sim \Delta \Sigma \left(x,{Q}^2\right)\sim \Delta G\left(x,{Q}^2\right)\sim {\left(\frac{1}{2}\right)}^{3.66\sqrt{\frac{\alpha_s{N}_c}{2\uppi}}}, $$ L q + q ¯ x Q 2 ~ L G x Q 2 ~ ∆ Σ x Q 2 ~ ∆ G x Q 2 ~ 1 2 3.66 α s N c 2 π , in agreement with [2] within the precision of our numerical evaluation. (Here Nc is the number of quark colors.) We also investigate the ratios of the quark and gluon OAM distributions to their helicity distribution counterparts in the small-x region.

AbstractLattice calculations of the proton spin components is reviewed. The lattice results of the quark spin from the axial-vector current matrix element at ∼ 0.3−0.4 is smaller than those from the constituent quark models. This is largely due to the fact that the vacuum polarization contribution from the disconnected insertion is negative. Its connection with the anomalous Ward identity is clarified and verified numerically. This resolves the contentious issue in the “proton spin crisis.” The glue spin and angular momentum are found to be large and there is notable contribution from the quark orbital angular momentum. Renormalization, mixing, and normalization of the quark and glue angular momenta are discussed. With sufficient precision, they can be compared with more precise experimental measurements when the electron-ion collider facility is available.

We discuss the negativity of the moment of inertia of (quark-)gluon plasma in a window of “supervortical” range of temperatures above the deconfining phase transition, T≃(1…1.5)Tc, found recently in numerical Monte Carlo simulations by two independent methods. In our work, we confirm numerically that the origin of this effect is rooted in the thermal evaporation of the nonperturbative chromomagnetic condensate. We argue that the negative moment of inertia of gluon plasma indicates the presence of a novel effect, the negative spin-vortical coupling for gluons resulting in a negative gluonic Barnett effect: the spin polarization of gluons exceeds the total angular momentum of rotating plasma, thus forcing the orbital angular momentum to take negative values in the supervortical range of temperatures. Published by the American Physical Society 2024

The object of mapping is to produce a "correct" relational model of the terrain. Its assumptions are that the objects in the world to be mapped are real and objective, and that they enjoy an existence independent of the cartographer; that their reality can be expressed in mathematical terms; that systematic observation and measurement offer the only route to cartographic truth; and that this truth can be independently verified. -- J. B. Harley, "Deconstructing the Map" Cartography, in its pragmatic operation under these assumptions, avoids almost all of the problems of representation with which cultural studies is only too familiar. Maps are representations, and all representations, even "scientific" ones, are cultural signs rather than truths produced in an ideological vacuum. The notion that mathematics, as a tool of Renaissance rationality, allowed real, objective detachment from an object of study was slowly absorbed into the cartographic tradition of Europe about four hundred years ago. "From at least the seventeenth century onward there was an epistemic break in activities such as cartography and architecture, and European map makers increasingly promoted what we would describe today as a standard scientific model of knowledge and cognition" (Harley 234). This model, in its increasing reliance upon mathematics and mathematical probability, essentially avoids or denies the objection that scientific observation and interpretation, and especially the technological gaze of its lens, produce anything other than objective, "real" knowledge. Through a mathematical detachment from the world, aided by the gaze of the lens, we see not the world itself (which includes us in its unmappable flux) but the numbers, straight lines and generalisations (which do not) that modern maps, including photographs, must employ to give the world fixed form and meaning. We find this model of cartography most impressively represented today in NASA's Mars Global Surveyor (MGS) probe, not merely as a sign of the technical success of mathematics, but also of its conceptual failure to provide the "true" representations of terrain to which a truly scientific cartography must aspire. MGS's 1998 attempt to "solve" the controversy surrounding a particularly contentious area on Mars, called Cydonia, with newer, "truer" images of the infamous Face on Mars was, contrary to popular opinion, an unsuccessful one; unsuccessful because NASA failed to remove all reasonable doubt that the Face was a natural geological formation. Not that this was particularly evident from media coverage of the image's release and reception -- the maverick researchers who comprised the protest were given a less than admirable hearing at the trial. Australian headlines reported that the Mars "romantics" (The Australian) had their Face theory "scuttled" (Courier-Mail). Professor Stanley V. McDaniel was demoted to "Mr McDaniel" in the The Australian, someone who wants NASA to continue re-imaging Cydonia to document other nearby features because "he believes [they] are further evidence of a Martian civilisation" (6). Also misrepresented was the like-minded, if slightly more adventurous researcher, Richard Hoagland, author of the underground classic, The Monuments of Mars: A City on the Edge of Forever (1987). Hoagland carelessly became (in both newspapers) Richard "Hoaglund", "leader of the movement" that believes the face is a monument left in Mars's Cydonia region by an ancient civilisation. The Australian, in line with the rest of the Earth's media, was apparently closing the door on the annoyingly persistent research into the Artificial Origin at Cydonia (AOC) hypothesis, which actually "does not claim that there is proof of artificial features on Mars, but that the probability of there being artificial features is strong enough to make new high-resolution photographs a top priority for any future mission to that planet" (McDaniel 2). Rather than confront the hypothesis itself, The Australian merely reminded us that "despite the image being 10 times better than the Viking photograph [a simplified qualification of the imaging process], it seems that some people still want to dream about ancient Martians building huge monuments to themselves" (The Australian). Dr. Mark J. Carlotto, a widely published specialist in the areas of digital image processing, pattern recognition, and computer vision, apparently still wants to dream that dream. An advocate of the AOC hypothesis, he notes that close examination of the image reveals the formation to be rough and highly eroded. Many have therefore concluded that the Face is natural. But others contend that if the Face is artificial it must certainly be very old and highly eroded. Thus the question remains as to how to distinguish an eroded artificial feature from a natural one. (Carlotto) This interestingly portentous question is one which NASA's Jet Propulsion Laboratory (JPL) and their contracted image processors, the privately owned Malin Space Science Systems (MSSS) have been somewhat reluctant to confront since the image of the Face was first captured in Viking frame 35A72. NASA's inaugural public statement on the Cydonia issue, for example, was handled ... "clumsily". As McDaniel reports: Upon the discovery of the Face in July, 1976, a Viking Project Scientist held up Viking frame 35A72, containing the Face, and announced to the assembled press corps that in a picture taken a few hours later "it all went away; it was just the way the light fell on it" -- but with a significant omission: the alleged later photograph, in which the facial features were supposed to have disappeared, was not shown for comparison [because] the statement could not possibly have been true. Frame 35A72 was taken in the early evening at approximately 6pm local time (sun angle 10 degrees). The object was in darkness a few hours later; the spacecraft, with an orbital period of about 24 hours, was no longer in a position to re-photograph the site; nor would it return to the site for many more orbits to come. Thus NASA's first official response to this strange object was an inexplicable misstatement based upon an apparent impossibility. (McDaniel 11-2) Things did not improve from there. NASA was never able to produce the elusive second photograph, yet continued to maintain that it both existed and conclusively disproved that the landform in question could possibly be artificial. In May 1993 the paradox attracted the attention of Senator John Glenn, who received (along with at least ten other members of the House and the Senate) a copy of the NASA document "Information on NASA's Re-Photographing of the Cydonia Region of Mars", which still held that the Face disappeared in the different lighting angles of a separate frame, which it did not reference. Finally in June 1993, after another inquiry by Senator Dianne Feinstein, a revised draft was issued which omits reference to the mysterious "real" photograph of the Face (McDaniel 12-3). NASA's next attempt to re-image Mars, including Cydonia, was the Observer probe, which failed to observe much at all and was declared lost in space. In conjunction with the recent mysterious failure of the Russian Phobos probe, and NASA's constant public relations blunders, conspiracy theories abounded. Was there something lurking at the threshold? The answer came in 1998 through the MGS, from which MSSS had produced a newer, clearer, "truer" image of the contentious feature which seemed to confirm Dr. Michael Malin's own earlier (and strangely self-contradictory) evaluation of 35A72: "it's simply a funny looking hill -- there is nothing unusual about it" (McDaniel 55). The MGS image certainly appeared, at least to the "naked eye" perusing the newspaper, to be just that. The wilderness had been tamed, and the coals cooled, temporarily. We had melted the witch. But exorcisms are never "final". Although NASA had apparently relegated the monstrous Face back to the realm of nature, restoring it within the parameters of conventional geology, McDaniel, Carlotto and others have maintained that NASA's conclusions were drastically premature, noting, as mentioned previously, that if the Face is artificial it must certainly be very old and, considering the Martian environment, highly eroded (Carlotto). According to their independent research, detailed analysis of the MGS image (which NASA appears not to have commissioned), does not invalidate the hypothesis that the Face may be artificial. Rather, it confirms many of the facial features recorded by the Viking, provides further evidence for the formation's high degree of lateral symmetry, and illuminates more anomalous internal detail (Carlotto). The Face on Mars, like the classical monsters of history, will not die easily. Ironically, perusal of Carlotto's dense research is an entry into the latent but undeniable plasticity of numbers, which itself is the quality of the monster that haunts modern cartographic representation. Mathematics, in almost every field of application, is finding it increasingly difficult to keep its disordering unknowns at bay. Geographer Erol Torun, for example, examined the angles formed by the facets of the two-mile long "D & M pyramid" (named after its discoverers, Vincent DiPietro and Gregory Molenaar). As Brian O'Leary writes, he subsequently found that the ratios between the five principal angles at the pyramid apex "express the universal mathematical constants of the square roots of 2,3,5,6, e, and pi ... . These constants should be known by any civilisation possessing Egyptian level technology (or greater) ... . The constants themselves are universal because they exist regardless of the number of the base being used". Regarding the other angles, Torun continued to find mathematically significant numbers "no matter how I looked at the object" (O'Leary 210). As the Cydonia controversy seems to clearly demonstrate, rather than revealing obvious, fixed truths about the world, mathematics and the observational tools they inspire require us to learn to see an approximation of the object they construct and represent as "real". We are thus compelled to draw the Other closer, but not "really", through the technological gaze of the artificial lens, a gaze that works to mask its own latent epistemic crisis. Indeed, this very compulsion inspired the growth of popular microscopy in the mid-eighteenth century, which required a new mode of seeing that could only very generously be termed "observation". Captain Basil Hall vividly recalls a meeting of the Geological Society, when a bottle was produced which was said to contain certain zoophytes. It was handed round, in the first instance, among the initiated on the foremost benches, who commented freely with one another on the forms of the animals in the fluid; but, when it came to our hands, we could discover nothing in the bottle but the most limpid fluid, -- without any trace, so far as our optics could make out, of animals dead or alive, the whole appearing absolutely transparent. The surprise of the ignorant at seeing nothing was only equal to that of the learned who saw so much to admire; nor was it till we were specifically instructed what we were to look for, and the shape, size, and general aspect of the zoophytes pointed out, that our understandings began to co-operate with our eyesight in peopling the fluid, which, up to that moment, had seemed perfectly uninhabited. The wonder then was, how we could possibly have omitted seeing objects now so palpable. (Mantell 8) Indeed, as Harley indicates, the relationship between the geographic and microscopic gaze is fundamental to the modern cartographic tradition. He cites Monmonier and Schnell's Map Appreciation (1988) as a recent example: Geography thrives on cartographic generalisation. The map is to the geographer what the microscope is to the microbiologist, for the ability to shrink the earth and generalise about it ... the microbiologist must choose a suitable objective lens, and the geographer must select a map scale appropriate to both the phenomenon in question and the "regional laboratory" in which the geographer is studying it. (in Harley 245) Importantly for this discussion, through both microscopy and cartography, "photography has also played a large role in twentieth-century ethnological representation", writes James Duncan. What better way to assert the primacy of the visual, produce a "true" representation of the place in question and establish presence than through the use of photography? But the mimetic claims of photography can also be called into question. A camera is a machine constructed to produce an image based upon artificial perspective. Only if one accepts the claims of the naturalness of Renaissance artificial perspective can we accept photography as a mimetic representation of the world. Such claims can be cast in doubt, for example, by the failure of peoples unfamiliar with photographs to be able to "read" them. (43) At the end of the day, though, it all may have more to do with down-to-earth economics than Martian "geopolitics". For many researchers, McDaniel among them, NASA's evasive treatment of the Face and surrounding features (variously labelled the Tholus, the D&M pyramid, the Fort, and the City Square) suggests a cover-up. Specifically, a cover-up of NASA's own inexplicable lack of investigation into apparently artificial structures on the Martian surface. Since the Jet Propulsion Laboratory's data imaging is contracted to a private company legally unaccountable to the public, McDaniel has confronted the somewhat disheartening possibility that financial motives may be obscuring investigation into what seem to be the most intriguing features of the Martian surface. He "does not personally believe in the conspiracy theory", but simply suggests that the Cydonia controversy may demonstrate that the financial interests of Malin Space Science Systems have assumed higher priority than the search for extraterrestrial artefacts: The contract for the Mars Observer (now MGS) involved close to 10 million dollars for Malin Space Science Systems ... . If it became clear that the probability of artificial structures on Mars is very high [or even that such a probability existed], it seems the focus of investigation would shift radically. The emphasis would fall to an accelerated manned mission to Mars. Archaeologists and perhaps biologists would assume an increasingly important role. It would be the manned mission (Johnson Space Flight Centre), not JPL, that takes the driver's seat. (McDaniel 1999) In other words, by producing results which indicated that the Cydonia region was worthy of closer attention, MSSS would jeopardise the future of its own multi-million dollar contract with NASA's Jet Propulsion Laboratory -- hardly a wise business venture, regardless of their geopolitical stance. But whatever the "true" source of the Martian controversy (it is, after all, the mythic planet of war), it seems undeniable that the Face on Mars is at once both an appropriately postmodern enigma and a genuine cartographic anomaly. For we find embodied within its monstrous form (through the lens), the message that our gaze is destined to be returned by ourselves. From the stars to the quarks, "we" seem to forever inhabit the very wilderness our technological gaze functions to both distance and draw closer; to abject. References Berland, Jody. "Mapping Space: Imaging Technologies and the Planetary Body." Technoscience and Cyberculture. Eds. Stanley Aronowitz, Barbara Martinsons, and Michael Menser. New York: Routledge, 1996. 123-37. Bull, Sandra. "Images from Mars Scuttle Face Theory." The Courier-Mail 8 April 1998. Carlotto, Mark J. "Analysis of Global Surveyor Imagery of the Face on Mars." 1998. 4 Oct. 2000 <http://www.psrw.com/~markc/Articles/MGSreport/paper.php>. ---. "New Cydonia Images -- April 2000: Preliminary Data Analysis." 2000. 4 Oct. 2000 <http://www.psrw.com/~markc/Articles/April_2000/April2000.php>. Crowley, Brian, and James J. Hurtak. The Face on Mars: Evidence of a Lost Martian Civilisation. 1986. Melbourne: Sun/Macmillan, 1989. Duncan, James. "Sites of Representation: Place, Time and the Discourse of the Other." Place/Culture/Representation. Eds. James Duncan and David Ley. London: Routledge, 1993. 39-56. Harley, J. B. "Deconstructing the Map." Writing Worlds: Discourse, Text and Metaphor in the Representation of Landscape. Eds. Trevor J. Barnes and James Duncan. London: Routledge, 1992. 231-47. Leech, Graeme. "Mars Romantics Face the Truth: There's Nothing Out There." The Australian 8 April 1998. Mantell, Gideon Algernon. The Invisible World Revealed by the Microscope; or, Thoughts on Animalcules. London: John Murray, 1850. McDaniel, Stanley V. The McDaniel Report: On the Failure of Executive, Congressional and Scientific Responsibility in Investigating Possible Evidence of Artificial Structures on the Surface of Mars and in Setting Mission Priorities for NASA's Mars Exploration Program. Berkeley: North Atlantic, 1993. ---. "Here It Is! But What Is It?" 1998. 4 Oct. 2000 <http://www.mcdanielreport.com/homepage.htm>. ---. "The Cydonia Question: Where Do We Stand?" 1999. 4 Oct. 2000. <http://www.mcdanielreport.com/standing.php>. O'Leary, Brian. "Mars and the Search for Extraterrestrial Life." Suppressed Inventions and Other Discoveries. Ed. Jonathan Eisen. Auckland: AIT, 1994. 204-13. Picknett, Lynn, and Clive Prince. The Stargate Conspiracy: Revealing the Truth behind Extraterrestrial Contact, Military Intelligence and the Mysteries of Ancient Egypt. London: Little, Brown and Co., 1999. Citation reference for this article MLA style: Adam Dodd. "'Unacceptable Renewals': The Geopolitics of Martian Cartography." M/C: A Journal of Media and Culture 3.6 (2000). [your date of access] <http://www.api-network.com/mc/0012/mars.php>. Chicago style: Adam Dodd, "'Unacceptable Renewals': The Geopolitics of Martian Cartography," M/C: A Journal of Media and Culture 3, no. 6 (2000), <http://www.api-network.com/mc/0012/mars.php> ([your date of access]). APA style: Adam Dodd. (2000) 'Unacceptable renewals': the geopolitics of Martian cartography. M/C: A Journal of Media and Culture 3(6). <http://www.api-network.com/mc/0012/mars.php> ([your date of access]).