Conventional Forces can Explain the Anomalous Acceleration of Pioneer 10

Anderson, et al. find the measured trajectories of Pioneer 10 and 11 spacecraft deviate from the trajectories computed from known forces acting on them. This unmodelled acceleration (and the less well known, but similar, unmodelled torque) can be accounted for by non-isotropic radiation of spacecraft heat. Various forms of non-isotropic radiation were proposed by Katz, Murphy, and Scheffer, but Anderson, et al. felt that none of these could explain the observed effect. This paper calculates the known effects in more detail and considers new sources of radiation, all based on spacecraft construction. These effects are then modelled over the duration of the experiment. The model reproduces the acceleration from its appearance at a heliocentric distance of 5 AU to the last measurement at 71 AU to within 10 percent. However, it predicts a larger decrease in acceleration between intervals I and III of the Pioneer 10 observations than is observed. This is a 2 sigma discrepancy from the average of the three analyses (SIGMA, CHASMP, and Markwardt). A more complex (but more speculative) model provides a somewhat better fit. Radiation forces can also plausibly explain the previously unmodelled torques, including the spindown of Pioneer 10 that is directly proportional to spacecraft bus heat, and the slow but constant spin-up of Pioneer 11. In any case, by accounting for the bulk of the acceleration, the proposed mechanism makes it much more likely that the entire effect can be explained without the need for new physics.Comment: Final minor changes for publication - added explanation of acronyms, added to RTG asymmetry argument.. Was: 12 pages, 9 figures, major revision. Added discussion of gas leaks and spin history, a radiation based explanation of spin changes, and references to re-analysis of Markwardt. Fixed radio forces, tuned models. Was: 7 pages, 5 figures; added liklihood calculations in body and abstract per suggestio

Apraxia in progressive nonfluent aphasia

The clinical and neuroanatomical correlates of specific apraxias in neurodegenerative disease are not well understood. Here we addressed this issue in progressive nonfluent aphasia (PNFA), a canonical subtype of frontotemporal lobar degeneration that has been consistently associated with apraxia of speech (AOS) and in some cases orofacial apraxia, limb apraxia and/or parkinsonism. Sixteen patients with PNFA according to current consensus criteria were studied. Three patients had a corticobasal syndrome (CBS) and two a progressive supranuclear palsy (PSP) syndrome. Speech, orofacial and limb praxis functions were assessed using the Apraxia Battery for Adults-2 and a voxel-based morphometry (VBM) analysis was conducted on brain MRI scans from the patient cohort in order to identify neuroanatomical correlates. All patients had AOS based on reduced diadochokinetic rate, 69% of cases had an abnormal orofacial apraxia score and 44% of cases (including the three CBS cases and one case with PSP) had an abnormal limb apraxia score. Severity of orofacial apraxia (but not AOS or limb apraxia) correlated with estimated clinical disease duration. The VBM analysis identified distinct neuroanatomical bases for each form of apraxia: the severity of AOS correlated with left posterior inferior frontal lobe atrophy; orofacial apraxia with left middle frontal, premotor and supplementary motor cortical atrophy; and limb apraxia with left inferior parietal lobe atrophy. Our findings show that apraxia of various kinds can be a clinical issue in PNFA and demonstrate that specific apraxias are clinically and anatomically dissociable within this population of patients

Moving up and down in the generic multiverse

We give a brief account of the modal logic of the generic multiverse, which is a bimodal logic with operators corresponding to the relations "is a forcing extension of" and "is a ground model of". The fragment of the first relation is called the modal logic of forcing and was studied by us in earlier work. The fragment of the second relation is called the modal logic of grounds and will be studied here for the first time. In addition, we discuss which combinations of modal logics are possible for the two fragments.Comment: 10 pages. Extended abstract. Questions and commentary concerning this article can be made at http://jdh.hamkins.org/up-and-down-in-the-generic-multiverse

Non-Archimedean character of quantum buoyancy and the generalized second law of thermodynamics

Quantum buoyancy has been proposed as the mechanism protecting the generalized second law when an entropy--bearing object is slowly lowered towards a black hole and then dropped in. We point out that the original derivation of the buoyant force from a fluid picture of the acceleration radiation is invalid unless the object is almost at the horizon, because otherwise typical wavelengths in the radiation are larger than the object. The buoyant force is here calculated from the diffractive scattering of waves off the object, and found to be weaker than in the original theory. As a consequence, the argument justifying the generalized second law from buoyancy cannot be completed unless the optimal drop point is next to the horizon. The universal bound on entropy is always a sufficient condition for operation of the generalized second law, and can be derived from that law when the optimal drop point is close to the horizon. We also compute the quantum buoyancy of an elementary charged particle; it turns out to be negligible for energetic considerations. Finally, we speculate on the significance of the absence from the bound of any mention of the number of particle species in nature.Comment: RevTeX, 16 page

Reprints, international markets and local literary taste: New empiricism and Australian literature

Taking a cue from Franco Moretti's research, my article applies statistical methods to probe the history of publishing Australian novels both locally and internationally. By temporarily suspending our discipline's preoccupation with close readings and canonical judgements, I aim to demonstrate how the computational analysis of large-scale publication data about Australian novels can also provoke alternative kinds of, and responses to, Australian literary history

An evaluation of mark and recapture techniques for estimating tigerfish biomass in Lake Kariba

The effectiveness of 2 mark and recapture techniques was evaluated using tiger fish, Hydrocynus vittatus. The 2 techniques used were: tagging with a plastic tag and fluorescent spray marking. While the tagging method resulted as the logical method to use within the constraints of the tiger fish study, it cannot be considered completely reliable for the estimation of population size in Lake Kariba

Pagans and Christians at the frontier: Viking burial in the Danelaw

[FIRST PARAGRAPH] The Vikings are the victims of cultural stereotyping (see e.g. Wawn 2000). In the popular imagination they provide the comic-book archetypal pagans: marauding shaggy war bands living and dying by the sword, with no respect for person or property, and least of all for the hallowed monasteries and clerics of Anglo-Saxon England. They worshipped violent and unforgiving Gods who inhabited the dark places of Northern Europe and they sacrificed animals and humans with complete disregard for Christian ethics. The Viking warrior aspired to the glorious death which would convey him on the journey to Valhalla where he would feast until Ragnorok. On the other hand, the scholarly world, faced with an acute lack of archaeological evidence for Pagan hordes, has created an alternative stereotype of the peaceful immigrant and trader eager to take on all the trappings of the host society, including its religion. In Anglo-Saxon England, within the space of a single generation, pagan warriors had become Christian farmers. Christian burial was rapidly adopted (Wilson 1967), many choosing to be buried in churchyards (Graham-Campbell 1980). By the tenth century their ferocious leaders were commissioning stone crosses and establishing private chapels on their new estates

The surface features and soil pattern of the Hamilton basin

The Holocene history of the Hamilton basin and development of the soil pattern are closely related. The basin was partly filled by the large alluvial fan of the Waikato River which partly buried a hilly, ash-covered landscape. The normal depositional pattern of fans is recognisable (apex of coarse sediments; middle part with ridges of coarse sediments and swales with fine sediments; toe of fine sediments) but has been modified by changing river courses during fan building. Each of these courses was flanked by levees which dammed valleys and embayments and blocked drainage to form lakes. The lakes were the sources of the present day peat bogs. The properties of the soils developed on the wide range of parent materials and landforms in the basin are summarised

The Baosteel Group – A national champion amongst national champions

In comparison to many of the Chinese and Indian state-owned enterprises examined in this volume, the institutional and competitive position of the Baosteel Group is somewhat unique. First, Baosteel stands out as one of the major success stories of recent Chinese state-owned enterprise (SOE) reform. Created as a national steel champion by the Chinese government in the early years of the reform period, and benefiting from the industrial policy support this status has brought during the intervening three decades, Baosteel has earned the status of one of China’s most internationally competitive SOEs. However, Baosteel is also unique in that it does not dominate the Chinese steel sector. Accounting for only a small share of Chinese steel production, Baosteel’s position is one of a technological leader within a competitive market structure populated by a large ‘national champions group’ of SOEs. Moreover, Baosteel has also faced special obligations to implement national industrial policies, by acting as a technological leader tasked with the role of acquiring and upgrading ailing steelmakers. Understanding Baosteel’s position within the Chinese steel sector as a ‘national champion amongst national champions’ is critical to explaining its operational characteristics, its special relationship with the Chinese government, and the benefits and costs this has carried for the firm