A Chiral Spin Theory in the Framework of an Invariant Evolution Parameter Formalism

We present a formulation for the construction of first order equations which describe particles with spin, in the context of a manifestly covariant relativistic theory governed by an invariant evolution parameter; one obtains a consistent quantized formalism dealing with off-shell particles with spin. Our basic requirement is that the second order equation in the theory is of the Schr\"{o}dinger-Stueckelberg type, which exhibits features of both the Klein-Gordon and Schr\"{o}dinger equations. This requirement restricts the structure of the first order equation, in particular, to a chiral form. One thus obtains, in a natural way, a theory of chiral form for massive particles, which may contain both left and right chiralities, or just one of them. We observe that by iterating the first order system, we are able to obtain second order forms containing the transverse and longitudinal momentum relative to a time-like vector $t_{\mu}t^{\mu}=-1$ used to maintain covariance of the theory. This time-like vector coincides with the one used by Horwitz, Piron, and Reuse to obtain an invariant positive definite space-time scalar product, which permits the construction of an induced representation for states of a particle with spin. We discuss the currents and continuity equations, and show that these equations of motion and their currents are closely related to the spin and convection parts of the Gordon decomposition of the Dirac current. The transverse and longitudinal aspects of the particle are complementary, and can be treated in a unified manner using a tensor product Hilbert space. Introducing the electromagnetic field we find an equation which gives rise to the correct gyromagnetic ratio, and is fully Hermitian under the proposed scalar product. Finally, we show that the original structure of Dirac'sComment: Latex, 61 pages. Minor revisions. To be published in J. Math. Phy

New Data on the Origin of Modern Man in the Levant

Anthropolog

Bone marrow mesenchymal stem cells do not enhance intra-synovial tendon healing despite engraftment and homing to niches within the synovium

Intra-synovial tendon injuries display poor healing, which often results in reduced functionality and pain. A lack of effective therapeutic options has led to experimental approaches to augment natural tendon repair with autologous mesenchymal stem cells (MSCs) although the effects of the intra-synovial environment on the distribution, engraftment and functionality of implanted MSCs is not known. This study utilised a novel sheep model which, although in an anatomically different location, more accurately mimics the mechanical and synovial environment of the human rotator cuff, to determine the effects of intra-synovial implantation of MSCs

Persistent Place-Making in Prehistory: the Creation, Maintenance, and Transformation of an Epipalaeolithic Landscape

Most archaeological projects today integrate, at least to some degree, how past people engaged with their surroundings, including both how they strategized resource use, organized technological production, or scheduled movements within a physical environment, as well as how they constructed cosmologies around or created symbolic connections to places in the landscape. However, there are a multitude of ways in which archaeologists approach the creation, maintenance, and transformation of human-landscape interrelationships. This paper explores some of these approaches for reconstructing the Epipalaeolithic (ca. 23,000–11,500 years BP) landscape of Southwest Asia, using macro- and microscale geoarchaeological approaches to examine how everyday practices leave traces of human-landscape interactions in northern and eastern Jordan. The case studies presented here demonstrate that these Epipalaeolithic groups engaged in complex and far-reaching social landscapes. Examination of the Early and Middle Epipalaeolithic (EP) highlights that the notion of “Neolithization” is somewhat misleading as many of the features we use to define this transition were already well-established patterns of behavior by the Neolithic. Instead, these features and practices were enacted within a hunter-gatherer world and worldview

Nonseptic tenosynovitis of the digital flexor tendon sheath caused by longitudinal tears in the digital flexor tendons: a retrospective study of 135 tenoscopic procedures

To determine the prevalence of LTs of the digital flexor tendons in a large population of horses undergoing diagnostic tenoscopy of the DFTS and to assess the outcome of surgical treatment and the factors influencing the outcome. Methods: Medical records of 130 horses with chronic tenosynovitis of the DFTS that had tenoscopic surgery between 1999 and 2009 were evaluated. One hundred and thirty-five DFTSs were examined. LTs were diagnosed in 104 DFTSs in 101 horses and long-term follow-up was obtained. Results: Seventy-eight percent of the horses with a nonseptic tenosynovitis of the DFTS had a LT. Preoperative ultrasonographic examination diagnosed tears in 76% of the cases. In showjumpers forelimbs were more frequently affected than hindlimbs (88 vs. 12%), with the right front having a higher incidence of injury than the left front (76 vs. 24%). Seventy-nine percent of the tears involved the deep digital flexor tendon (DDFT) and 87% were located on the lateral tendon border. Thirty-seven horses (38%) returned to an equal or higher level of work. The use of a radiofrequency probe (coblation) was associated with a lower level of performance and decreased the cosmetic end result. Persistence of marked post operative distension of the DFTS carried a poor prognosis for return to previous level of work. Conclusions and potential relevance: A guarded prognosis for future soundness should be given to horses presented for treatment of LTs of the digital flexor tendons. The use of coblation wands had a negative effect on the final outcome

The Rhafas Cave (Morocco): Chronology of the mousterian and aterian archaeological occupations and their implications for Quaternary geochronology based on luminescence (TL/OSL) age determinations

The Middle Palaeolithic chronology of the Maghreb region of North Africa is poorly known because of the paucity of sites with a long stratigraphy and the limited number of available radiometric dates. In this paper, we report the age-estimates obtained by the TL and OSL methods on sediments and burnt lithic samples from the Rhafas Cave in Eastern Morocco. Our results indicate that the Mousterian is largely earlier than 100 ka, that the latest Mousterian dates to OIS 5 between 90–80 ka and the Mousterian to Aterian transition occurred about 70–80 ka, at the end of OIS 5 or during OIS 4. These dates will be most useful in the construction of a chronological framework of this unique sequence and for the interpretation of paleoenvironmental information

Estimating thumb–index finger precision grip and manipulation potential in extant and fossil primates

Primates, and particularly humans, are characterized by superior manual dexterity compared with other mammals. However, drawing the biomechanical link between hand morphology/behaviour and functional capabilities in non-human primates and fossil taxa has been challenging. We present a kinematic model of thumb–index precision grip and manipulative movement based on bony hand morphology in a broad sample of extant primates and fossil hominins. The model reveals that both joint mobility and digit proportions (scaled to hand size) are critical for determining precision grip and manipulation potential, but that having either a long thumb or great joint mobility alone does not necessarily yield high precision manipulation. The results suggest even the oldest available fossil hominins may have shared comparable precision grip manipulation with modern humans. In particular, the predicted human-like precision manipulation of Australopithecus afarensis, approximately one million years before the first stone tools, supports controversial archaeological evidence of tool-use in this taxon

Thermoluminescence dates for the Neanderthal burial site at Kebara in Israel

International audienceThe origins of modern man are a subject of controversy among palaeoanthropologists concerned with human evolution1–3. Particularly heavily debated is the dating of hominid remains uncovered in southwestern Asia, because middle palaeolithic sites have provided skeletal remains classified as representing Neanderthals (Homo sapiens neanderthalensis at Tabun, Amud, Kebara and Shanidar caves) and proto-Cro-Magnons (Homo sapiens sapiens at Skhul and Qafzeh caves). This situation differs considerably from that of Western Europe, where only Neanderthal remains are known from archaeological deposits of this period, or that of the African continent, where no Neanderthal remains have so far been found. Two opposing hypotheses have been offered to explain the relations between Neanderthals and the earliest modern Homo sapiens: first that modern Homo sapiens appeared very early in the Mediterranean Levant and coexisted with a population of Neanderthals who had arrived at a later date; and second that modern humans developed from the local Neanderthal population in southwestern Asia. Recent excavations at the Kebara cave yielded Neanderthal burial in a well-documented stratigraphic and cultural Mousterian sequence4,5. We now report that ther-moluminescence dates from 38 specimens of burnt flint recovered from 4 m of Kebara deposits range from about 60,000 to 48,000 years before present (BP), indicating that Neanderthals were present in the Levant in the latter part of the middle Palaeolithic

Hayonim Cave: a TL-based chronology of a Levantine Mousterian sequence

International audienceThe thermoluminescence dating method was applied to 77 heated flints from the Mousterian layers of Hayonim Cave in order to provide a precise TL-based chronology for this important Levantine sequence. A detailed dosimetric study was performed by using 76 dosimeter capsules and revealed strong spatial dose-rate variations. In parallel, Fourier transform infrared spectrometry enabled the identification of various mineral assemblages in the sediments of the cave and to localize the boundaries of these assemblages. By comparing these two data sets, it is shown that low dose-rate values (not, vert, similar500 μGy/a) are systematically recorded in areas where the calcite-dahllite (CD) assemblage is preserved, whereas higher values (up to 1300 μGy/a) are associated with the leucophosphite, montgomeryite, variscite and siliceous aggregates (LMVS) assemblage. The dosimetric and mineralogical information was combined in order to assess, where possible, the dose-rate experienced by each flint during its burial. Some of the flint samples analyzed were too close to mineral assemblage boundaries and were therefore discarded. This rigorous selection led to TL ages ranging from 230 to 140 ka for the lower part of the Mousterian sequence (layers F and Lower E), which contains lithic industries characterized by blade production using the laminar method