3,522 research outputs found

    A New Conception of War

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    In 1989, the Marine Corps formally adopted a theory of conflict called maneuver warfare and described its tenets in a short but revolutionary doctrinal manual simply titled Warfighting. This conflict theory evolved along two paths that wound their way through the landscape of the late Cold War period before coming together in 1989. A New Conception of War traces this story from the post–Vietnam War years to the present. The first path was forged by U.S. Air Force colonel John R. Boyd, whose ideas on warfare were shaped by a military career during the height of the Cold War and his own passion for challenging conventional wisdom in the search for new and useful ideas. The second path was navigated by many thinkers within the Marine Corps during a period of institutional soul-searching after Vietnam, driven by the Corps’ imperative to adapt to the exigencies of the day and thus remain a useful contributor to national defense. Drawing on new and previously unpublished material from the major players of this period, including a full transcript of Boyd’s “Patterns of Conflict” lecture, A New Conception of War captures a period of remarkable intellectual ferment within the Marine Corps and the development of a unique conceptual framework for warfighting that continues to inspire Marines today

    A New Conception of War: John Boyd, the U.S. Marines, and Maneuver Warfare

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    Vascular perfusion chilling of red meat carcasses - A feasibility study.

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    Meat carcasses must be chilled to below 7°C before leaving the slaughterhouse. Typically this is done by passing cold air over the surfaces of eviscerated and de-hided carcasses. This surface cooling can take many hours to reduce centre temperatures to below 7°C. In vascular perfusion chilling (VPC), a cold fluid is circulated through the intact vascular system, offering significant reductions in cooling time. This paper describes a small feasibility study to evaluate vascular perfusion techniques for rapid chilling of lamb carcasses using a proprietary Flo-ice(™) system. This produces pumpable ice slurries containing very fine ice particles, suitable for circulating through vascular systems. VPC was found to be capable of rapid initial reduction of carcass temperatures in comparison with air chilling (mean times to 20°C in deep legs were reduced from 2.6 to 1.3h, which was significantly different at P<0.05). In all cases however, uptake of perfusate into the carcasses occurred. This limited the duration of the perfusion treatment and as a result restricted the period of enhanced cooling. Samples from carcasses treated with VPC were lighter (P<0.05, with mean measured L value increasing from 43.4 to 46.8) and more yellow (P<0.05, with mean measured b value increasing from 6.7 to 7.9) than samples from conventionally chilled carcasses, and had lower shear force values when cooked (P<0.05, with mean force reducing from 10.0 to 6.8kg). This was most probably due to the added water in the meat. Microbial quality of the meat was not significantly affected by the perfusion treatments

    Microstructural characterisation of TiAlTiAu and TiAlPdAu ohmic contacts to AlGaN/GaN

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    Ti/Al/Ti/Au and Ti/Al/Pd/Au contacts to AlGaN/GaN have been investigated to ascertain the effect of annealing temperature on the structural evolution of the contacts. Ti/Al/Ti/Au contacts become ohmic after rapid thermal annealing at 750°C or higher, corresponding to the formation of an interfacial TiN phase, with inclusions penetrating through the AlGaN layer observed after annealing at 950°C. The Pd layer is shown to be more efficient at inhibiting diffusion of Au to the interface than Ti. Ohmic behaviour was not seen with the Ti/Al/Pd/Au scheme. Either the presence of Au at the interface may improve ohmic behaviour, or the Ti:Al ratio is insufficient in this scheme

    The Intermediate Luminosity Optical Transient SN 2010da: The Progenitor, Eruption and Aftermath of a Peculiar Supergiant High-mass X-ray Binary

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    We present optical spectroscopy, ultraviolet to infrared imaging and X-ray observations of the intermediate luminosity optical transient (ILOT) SN 2010da in NGC 300 (d=1.86 Mpc) spanning from -6 to +6 years relative to the time of outburst in 2010. Based on the light curve and multi-epoch SEDs of SN 2010da, we conclude that the progenitor of SN 2010da is a ~10-12 Msol yellow supergiant possibly transitioning into a blue loop phase. During outburst, SN 2010da had a peak absolute magnitude of M<-10.4 mag, dimmer than other ILOTs and supernova impostors. We detect multi-component hydrogen Balmer, Paschen, and Ca II emission lines in our high-resolution spectra, which indicate a dusty and complex circumstellar environment. Since the 2010 eruption, the star has brightened by a factor of ~5 and remains highly variable in the optical. Furthermore, we detect SN 2010da in archival Swift and Chandra observations as an ultraluminous X-ray source (L~6x10^{39} erg/s). We additionally attribute He II 4686 Angstrom and coronal Fe emission lines in addition to a steady X-ray luminosity of ~10^{37} erg/s to the presence of a compact companion.Comment: published; updated citations and other minor edit

    Microstructural characterisation of TiAlTiAu and TiAlPdAu ohmic contacts to AlGaN/GaN

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    Ti/Al/Ti/Au and Ti/Al/Pd/Au contacts to AlGaN/GaN have been investigated to ascertain the effect of annealing temperature on the structural evolution of the contacts. Ti/Al/Ti/Au contacts become ohmic after rapid thermal annealing at 750°C or higher, corresponding to the formation of an interfacial TiN phase, with inclusions penetrating through the AlGaN layer observed after annealing at 950°C. The Pd layer is shown to be more efficient at inhibiting diffusion of Au to the interface than Ti. Ohmic behaviour was not seen with the Ti/Al/Pd/Au scheme. Either the presence of Au at the interface may improve ohmic behaviour, or the Ti:Al ratio is insufficient in this scheme

    A variational approach to the QCD wave functional:Dynamical mass generation and confinement

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    We perform a variational calculation in the SU(N) Yang Mills theory in 3+1 dimensions. Our trial variational states are explicitly gauge invariant, and reduce to simple Gaussian states in the zero coupling limit. Our main result is that the energy is minimized for the value of the variational parameter away form the perturbative value. The best variational state is therefore characterized by a dynamically generated mass scale MM. This scale is related to the perturbative scale ΛQCD\Lambda_{QCD} by the following relation: αQCD(M)=π41N\alpha_{QCD}(M)={\pi\over 4}{1\over N}. Taking the one loop QCD β\beta- function and ΛQCD=150Mev\Lambda_{QCD}=150 Mev we find (for N=3) the vacuum condensate απ=0.008Gev4{\alpha\over \pi}= 0.008 Gev^4.Comment: 37 pages, (1 Figure available upon request), preprint LA-UR-94-2727, PUPT-149

    Exploring extensions to the standard cosmological model and the impact of baryons on small scales

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    It has been claimed that the standard model of cosmology (ΛCDM) cannot easily account for a number of observations on relatively small scales, motivating extensions to the standard model. Here, we introduce a new suite of cosmological simulations that systematically explores three plausible extensions: warm dark matter, self-interacting dark matter, and a running of the scalar spectral index of density fluctuations. Current observational constraints are used to specify the additional parameters that come with these extensions. We examine a large range of observable metrics on small scales, including the halo mass function, density, and circular velocity profiles, the abundance of satellite subhaloes, and halo concentrations. For any given metric, significant degeneracies can be present between the extensions. In detail, however, the different extensions have quantitatively distinct mass and radial dependencies, suggesting that a multiprobe approach over a range of scales can be used to break the degeneracies. We also demonstrate that the relative effects on the radial density profiles in the different extensions (compared to the standard model) are converged down to significantly smaller radii than are the absolute profiles. We compare the derived cosmological trends with the impact of baryonic physics using the EAGLE and ARTEMIS simulations. Significant degeneracies are also present between baryonic physics and cosmological variations (with both having similar magnitude effects on some observables). Given the inherent uncertainties both in the modelling of galaxy formation physics and extensions to ΛCDM, a systematic and simultaneous exploration of both is strongly warranted
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