563 research outputs found

    Reconciliation and relationship quality in Assamese macaques (Macaca assamensis)

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    A consistent conclusion in reconciliation research is that animals that reconcile are likely to have strong social bonds. This has led to the hypothesis that reconciliation occurs most often between valuable social partners. We tested this hypothesis in a group of Assamese macaques (Macaca assamensis) living near a temple in Assam, India. Using focal sample and ad libitum data collection, we recorded the occurrence of reconciliation, grooming, and agonistic aiding, and the outcomes of approach. We used matrix association methods (Tau(Kr) correlation) to correlate reconciliation with grooming, aiding, and approach outcome. Females reconciled more often with females with which they had stronger grooming and aiding relationships. The correlation between reconciliation and aiding was significant for support to the aggressor and the victim. In contrast, no such correlations with reconciliation were found for males. This study provides evidence that females reconcile most often with valuable and compatible social partners. The results do not support the relationship-quality hypothesis for males, and we suggest that future studies give more consideration to the possibility that males reconcile for reasons other than to repair relationships with valuable partners. (c) 2005 Wiley-Liss, Inc

    Radiocarbon Date List X: Baffin Bay, Baffin Island, Iceland, Labrador Sea, and the Northern North Atlantic

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    Date List X contains an annotated listing of 213 radiocarbon dates determined on samples from marine and terrestrial environments. The marine samples were collected from the East Greenland, Iceland, Spitzbergen, and Norwegian margins, Baffin Bay, and Labrador Sea. The terrestrial samples were collected from Vestfirdir, Iceland and Baffin Island. The samples were submitted by INSTAAR and researchers affiliated with INSTAAR\u27s Micropaleontology Laboratory under the direction of Dr.’s John T. Andrews and Anne E. Jennings. All of the dates from marine sediment cores were determined from either shells or foraminifera (both benthic and planktic). All dates were obtained by the Accelerator Mass Spectrometry (AMS) method. Regions of concentrated marine research include: Baffin Bay, Baffin Island, Labrador Sea, East Greenland fjords, shelf and slope, Denmark Strait, the southwestern and northwestern Iceland shelves, and Vestfirdir, Iceland. The non-marine radiocarbon dates are from peat, wood, plant microfossils, and mollusc. The radiocarbon dates have been used to address a variety of research objectives such as: 1. determining the timing of northern hemisphere high latitude environmental changes including glacier advance and retreat, and 2. assessing the accuracy of a fluctuating reservoir correction. Thus, most of the dates constrain the timing, rate, and interaction of late Quaternary paleoenvironmental fluctuations in sea level, glacier extent, sediment input, and changes in ocean circulation patterns. Where significant, stratigraphic and sample contexts are presented for each core to document the basis for interpretations

    Quantum Extremism: Effective Potential and Extremal Paths

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    The reality and convexity of the effective potential in quantum field theories has been studied extensively in the context of Euclidean space-time. It has been shown that canonical and path-integral approaches may yield different results, thus resolving the `convexity problem'. We discuss the transferral of these treatments to Minkowskian space-time, which also necessitates a careful discussion of precisely which field configurations give the dominant contributions to the path integral. In particular, we study the effective potential for the N=1 linear sigma model.Comment: 11 pages, 4 figure

    Advances in the genetic classification of amyotrophic lateral sclerosis

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    Purpose of review Amyotrophic lateral sclerosis (ALS) is an archetypal complex disease wherein disease risk and severity are, for the majority of patients, the product of interaction between multiple genetic and environmental factors. We are in a period of unprecedented discovery with new large-scale genome-wide association study (GWAS) and accelerating discovery of risk genes. However, much of the observed heritability of ALS is undiscovered and we are not yet approaching elucidation of the total genetic architecture, which will be necessary for comprehensive disease subclassification. Recent findings We summarize recent developments and discuss the future. New machine learning models will help to address nonlinear genetic interactions. Statistical power for genetic discovery may be boosted by reducing the search-space using cell-specific epigenetic profiles and expanding our scope to include genetically correlated phenotypes. Structural variation, somatic heterogeneity and consideration of environmental modifiers represent significant challenges which will require integration of multiple technologies and a multidisciplinary approach, including clinicians, geneticists and pathologists. Summary The move away from fully penetrant Mendelian risk genes necessitates new experimental designs and new standards for validation. The challenges are significant, but the potential reward for successful disease subclassification is large-scale and effective personalized medicine

    Non-Fermi liquid regime of a doped Mott insulator

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    We study the doping of a Mott insulator in the presence of quenched frustrating disorder in the magnetic exchange. A low doping regime δ<J/t\delta<J/t is found, in which the quasiparticle coherent scale is low : ϵF=J(δ/δ)2\epsilon_F^* = J (\delta/\delta^*)^2 with δ=J/t\delta^*=J/t (the ratio of typical exchange to hopping). In the ``quantum critical regime'' ϵF<T<J\epsilon_F^*<T<J, several physical quantities display Marginal Fermi Liquid behaviour : NMR relaxation time 1/T1const.1/T_1\sim const., resistivity ρdc(T)T\rho_{dc}(T) \propto T, optical lifetime \tau_{opt}^{-1}\propto \omega/\ln(\omega/\epstar) and response functions obey ω/T\omega/T scaling, e.g. Jqχ(q,ω)tanh(ω/2T)J\sum_q \chi''(q,\omega) \propto \tanh (\omega/2T). In contrast, single-electron properties display stronger deviations from Fermi liquid theory in this regime with a ω\sqrt{\omega} dependence of the inverse single-particle lifetime and a 1/ω1/\sqrt{\omega} decay of the photoemission intensity. On the basis of this model and of various experimental evidence, it is argued that the proximity of a quantum critical point separating a glassy Mott-Anderson insulator from a metallic ground-state is an important ingredient in the physics of the normal state of cuprate superconductors (particularly the Zn-doped materials). In this picture the corresponding quantum critical regime is a ``slushy'' state of spins and holes with slow spin and charge dynamics responsible for the anomalous properties of the normal state.Comment: 40 pages, RevTeX, including 13 figures in EPS. v2 : minor changes, some references adde

    Domain wall generation by fermion self-interaction and light particles

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    A possible explanation for the appearance of light fermions and Higgs bosons on the four-dimensional domain wall is proposed. The mechanism of light particle trapping is accounted for by a strong self-interaction of five-dimensional pre-quarks. We obtain the low-energy effective action which exhibits the invariance under the so called \tau-symmetry. Then we find a set of vacuum solutions which break that symmetry and the five-dimensional translational invariance. One type of those vacuum solutions gives rise to the domain wall formation with consequent trapping of light massive fermions and Higgs-like bosons as well as massless sterile scalars, the so-called branons. The induced relations between low-energy couplings for Yukawa and scalar field interactions allow to make certain predictions for light particle masses and couplings themselves, which might provide a signature of the higher dimensional origin of particle physics at future experiments. The manifest translational symmetry breaking, eventually due to some gravitational and/or matter fields in five dimensions, is effectively realized with the help of background scalar defects. As a result the branons acquire masses, whereas the ratio of Higgs and fermion (presumably top-quark) masses can be reduced towards the values compatible with the present-day phenomenology. Since the branons do not couple to fermions and the Higgs bosons do not decay into branons, the latter ones are essentially sterile and stable, what makes them the natural candidates for the dark matter in the Universe.Comment: 34 pages, 2 figures, JHEP style,few important refs. adde

    Low energy fast events from radon progenies at the surface of a CsI(Tl) scintillator

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    In searches for rare phenomena such as elastic scattering of dark matter particles or neutrinoless double beta decay, alpha decays of Rn222 progenies attached to the surfaces of the detection material have been identified as a serious source of background. In measurements with CsI(Tl) scintillator crystals, we demonstrate that alpha decays of surface contaminants produce fast signals with a characteristic mean-time distribution that is distinct from those of neutron- and gamma-induced events.Comment: 9 pages, 8 figure

    Measurement of the Ds lifetime

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    We report precise measurement of the Ds meson lifetime. The data were taken by the SELEX experiment (E781) spectrometer using 600 GeV/c Sigma-, pi- and p beams. The measurement has been done using 918 reconstructed Ds. The lifetime of the Ds is measured to be 472.5 +- 17.2 +- 6.6 fs, using K*(892)0K+- and phi pi+- decay modes. The lifetime ratio of Ds to D0 is 1.145+-0.049.Comment: 5 pages, 2 figures submitted to Phys. Lett.

    Confirmation of the Double Charm Baryon Xi_cc+ via its Decay to p D+ K-

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    We observes a signal for the double charm baryon Xi_cc+ in the charged decay mode Xi_cc+ -> p D+ K- to complement the previously reported decay Xi_cc+ -> Lambda_c K- pi+ in data from SELEX, the charm hadro-production experiment (E781) at Fermilab. In this new decay mode we observe an excess of 5.62 events over an expected background estimated by event mixing to be 1.38+/-0.13 events. The Poisson probability that a background fluctuation can produce the apparent signal is less than 6.4E-4. The observed mass of this state is (3518+/-3)MeV/c^2, consistent with the published result. Averaging the two results gives a mass of (3518.7+/-1.7)MeV/c^2. The observation of this new weak decay mode confirms the previous SELEX suggestion that this state is a double charm baryon. The relative branching ratio Gamma(Xi_cc+ -> pD+K-)/Gamma(Xi_cc+ -> Lambda_c K- pi+) = 0.36+/-0.21.Comment: 11 pages, 6 included eps figures. v2 includes improved statistical method to determine significance of observation. Submitted to PL
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