Ending the war on error: towards an archaeology of failure

Failure is a fundamental part of the human condition. While archaeologists readily identify large-scale failures, such as societal collapse and site abandonment, they less frequently consider the smaller failures of everyday life: the burning of a meal or planning errors during construction. Here, the authors argue that evidence for these smaller failures is abundant in the archaeological record but often ignored or omitted in interpretations. Closer examination of such evidence permits a more nuanced understanding both of the mundane and the larger-scale failures of the human past. Excluding failure from the interpretative toolbox obscures the reconstruction of past lives and is tantamount to denying the humanity of past peoples

Towards an antifragility framework in past human–environment dynamics

Scholarship on human–environment interactions tends to fall under two headings: collapse or resilience. While both offer valid explanatory frameworks for human–environment dynamics, both view stress as a net negative that, if unchecked, disrupts systems in equilibrium. Societies either succumb to stress (and collapse) or overcome stress and persist (demonstrate resilience). We re-evaluate the role of stress and advocate for a non-equilibrium approach to the study of past human–environment interactions. We draw inspiration from Nasim Taleb’s concept of ‘antifragility’, which posits a positive role of stress for increasingly complex systems. We apply antifragility as an explanatory framework to pre-Hispanic coastal Peru, where indigenous farmers adapted to the stresses of highly variable El Niño events through a variety of water management systems. Finally, we note that an antifragility approach highlights the beneficial role of stressors, and that avoiding stress altogether makes a system more fragile

Three-Omega Thermal-Conductivity Measurements with Curved Heater Geometries

The three-omega method, a powerful technique to measure the thermal conductivity of nanometer-thick films and the interfaces between them, has historically employed straight conductive wires to act as both heaters and thermometers. When investigating stochastically prepared samples such as two-dimensional materials and nanomembranes, residue and excess material can make it difficult to fit the required millimeter-long straight wire on the sample surface. There are currently no available criteria for how diverting three-omega heater wires around obstacles affects the validity of the thermal measurement. In this Letter, we quantify the effect of wire curvature by performing three-omega experiments with a wide range of frequencies using both curved and straight heater geometries on SiO$_2$/Si samples. When the heating wire is curved, we find that the measured Si substrate thermal conductivity changes by only 0.2%. Similarly, we find that wire curvature has no significant effect on the determination of the thermal resistance of a $\sim$65 nm SiO$_2$ layer, even for the sharpest corners considered here, for which the largest measured ratio of the thermal penetration depth of the applied thermal wave to radius of curvature of the heating wire is 4.3. This result provides useful design criteria for three-omega experiments by setting a lower bound for the maximum ratio of thermal penetration depth to wire radius of curvature.Comment: 4 pages, 3 figure

The Human Virome in Children and its Relationship to Febrile Illness

This study investigates the relationship of viruses to febrile illness in children. Subjects are normal children 2-36 months of age with fever along with normal children of the same age without fever, plus immunocompromised children with fever along with immunocompromised children without fever. Specimens obtained include blood, nasopharyngeal secretions, and feces. Specimens are analyzed using a panel of virus-specific PCR assays and also by high throughput sequencing using 454 and Illumina platforms

θ−\theta- Parameter in 2 Color QCD at Finite Baryon and Isospin Density

We use 2-color QCD as a model to study the effects of simultaneous presence of the so-called $\theta$ parameter, chemical potentials for baryon number, $\mu_B$ and for isospin charge, $\mu_I$. We pay special attention to $\theta$, $\mu_B$, $\mu_I$ dependence of different vacuum condensates, including chiral and diquark condensates, as well as the gluon condensate, $$, and the topological susceptibility. We find that two phase transitions of the second order will occur when $\theta$ relaxes from $\theta=2\pi$ to $\theta=0$, if $\mu$ is of order of the pion mass. We demonstrate that the transition to the superfluid phase at $\theta = \pi$ occurs at a much lower chemical potential than at $\theta = 0$. We also show that the strong $\theta$ dependence present near $\theta = \pi$ in vacuum (Dashen's phenomenon), becomes smoothed out in the superfluid phase. Finally, we comment on the relevance of this study for the real world with N_c=3

Effects of intersensory localization of spheres and prisms as measured in Harris type apparatus

The vision specialist often finds himself asking the question, What are the immediate effects of my lens and/or prism therapy on a given patient? If for example, a change in accommodation or convergence is effected by lenses, what will be the results of this change on the visual performance of the patient as far as his intersensory localizations of objects in space are concerned? Past experience by some traditional practitioners would dictate that positive lenses and prism base-in will tend to force a subject to localize farther out than his habitual localization pattern. Minus lenses·and prism base-out tend to localize closer than he normally would. This effect, they would say, is an illustration of the phenomenon known as SILO. The letters SILO stand for the phenomenon of smaller-in and larger-out. For example, if a subject views an object through minus spherical lenses or base-out prisms, he will experience the object as being smaller and closer whereas if he views the same object through plus spherical lenses or base-in prisms, he will experience the object as being larger and farther away. Our thesis deals only with half of the SILO effect, i.e., the perceived distance. Recently, some developmentalists have postulated that localization may be attributable to postural functions of accommodation. Specifically, since plus lenses move the posture out in space, the subject will localize farther out also. The opposite is true for minus lenses. On the other hand, some psychologists believe that the extraocular muscles relay information to the brain as to the position of the eyes in the orbit. Therefore, can we attribute changes in eye-hand coordination and intersensory localization to accommodation, convergence, or both? With this in mind it was our intention to investigate the above question utilizing the addition of spherical lenses and prisms over the habitually worn prescription of a subject in order to artificially change the accommodation and convergence and then measure the change in intersensory localization. Intersensory localization being the observer\u27s ability to judgementally or behaviourally map one modality on to another

Molecular Cloud Structure in the Magellanic Clouds: Effect of Metallicity

The chemical structure of neutral clouds in low metallicity environments is examined with particular emphasis on the H to H_2 and C+ to CO transitions. We observed near-IR H_2 lines and the CO J=1-0 line from 30 Doradus and N159/N160 in the Large Magellanic Cloud and from DEM S 16, DEM S 37, and LI-SMC 36 in the Small Magellanic Cloud. We find that the H_2 emission is UV-excited and that (weak) CO emission always exists (in our surveyed regions) toward positions where H_2 and [CII] emission have been detected. Using a PDR code and a radiative transfer code, we simulate the emission of line radiation from spherical clouds and from large planar clouds. Because the [CII] emission and H_2 emission arise on the surface of the cloud and the lines are optically thin, these lines are not affected by changes in the relative sizes of the neutral cloud and the CO bearing core, while the optically thick CO emission can be strongly affected. The sizes of clouds are estimated by measuring the deviation of CO emission strength from that predicted by a planar cloud model of a given size. The average cloud column density and therefore size increases as the metallicity decreases. Our result agrees with the photoionization regulated star formation theory by Mc Kee (1989).Comment: 45 Pages including 15 figures. To be published in the ApJ May 10, 1998 issue, Vol. 49

Long Phonon Mean Free Paths Observed in Cross-plane Thermal-Conductivity Measurements of Exfoliated Hexagonal Boron Nitride

Sub-micron-thick layers of hexagonal boron nitride (hBN) exhibit high in-plane thermal conductivity, useful optical properties, and serve as dielectric encapsulation layers with low electrostatic inhomogeneity for graphene devices. Despite the promising applications of hBN as a heat spreader, the thickness dependence of the cross-plane thermal conductivity is not known, and the cross-plane phonon mean free paths in hBN have not been measured. We measure the cross-plane thermal conductivity of hBN flakes exfoliated from bulk crystals. We find that the thermal conductivity is extremely sensitive to film thickness. We measure a forty-fold increase in the cross-plane thermal conductivity between 7 nm and 585 nm flakes at 295 K. We attribute the large increase in thermal conductivity with increasing thickness to contributions from phonons with long mean free paths (MFPs), spanning many hundreds of nanometers in the thickest flakes. When planar twist interfaces are introduced into the crystal by mechanically stacking multiple thin flakes, the cross-plane thermal conductivity of the stack is found to be a factor of seven below that of individual flakes with similar total thickness, thus providing strong evidence that phonon scattering at twist boundaries limits the maximum phonon MFPs. These results have important implications for hBN integration in nanoelectronics and improve our understanding of thermal transport in two-dimensional materials.Comment: 4 pages, 3 figure

The Large-Scale Polarization of the Microwave Foreground

Most of the useful information about inflationary gravitational waves and reionization is on large angular scales where Galactic foreground contamination is the worst, so a key challenge is to model, quantify and remove polarized foregrounds. We use the Leiden radio surveys to quantify the polarized synchrotron radiation at large angular scales, which is likely to be the most challenging polarized contaminant for the WMAP satellite. We find that the synchrotron E- and B-contributions are equal to within 10% from 408-820MHz with a hint of E-domination at higher frequencies. We quantify Faraday Rotation & Depolarization effects and show that they cause the synchrotron polarization percentage to drop both towards lower frequencies and towards lower multipoles.Comment: To be published in the proceedings of "The Cosmic Microwave Background and its Polarization", New Astronomy Reviews, (eds. S. Hanany and K.A. Olive). 4 pages. More foreground information at http://www.hep.upenn.edu/~angelica/foreground.html#polar or from [email protected]