648 research outputs found
Inefficient practice of flint heat treatment at Hasankeyf Höyük: An anti-functional view
This paper investigates the heat treatment of flint practiced at the Neolithic site of Hasankeyf Höyük in southeast Turkey. It does not involve petrographic or geochemical analysis to identify the physical and chemical evidence of heat treatment but aims to understand cultural aspects of the use of ancient lithic technology, using heat treatment as a case study. Heat treatment is a lithic production technique in which siliceous rocks are heated by controlled fire in order to improve their flaking quality. Archaeological evidence of heat treatment is seen all over the world, and numerous studies have contributed to the better understanding of this technique. However, what is particularly intriguing in the case of Hasankeyf Höyük is that there are many flint artefacts which were apparently overheated and unusable due to the frequent failure in achieving successful heat treatment. On the other hand, experimental studies using an electrical furnace and open fire show that once the appropriate heating time and temperature are learnt, the heat treatment of local flint at Hasankeyf Höyük is an easy process and does not require high technical skill. It is therefore suggested that heat treatment at this site was exercised along non-economic principles by people who were not very keen on improving technological efficiency, even when they could have easily done so
Solid State Diffusion Bonding of Silicon Nitride with Vanadium Foils(Materials, Metallurgy & Weldability)
Fidgety movements assessment accuracy survey in Japan
To investigate the accuracy of fidgety movements (FMs) assessment in Japanese assessors. Sixty specialists participated in the first survey. Of the participants, 18 were assessors certified by the GMs basic-training course. The surveys were composed of FMs assessment of 20 video clips. The correct assessment rates (CARs) were investigated. The survey videos were judged into three types: normal (F + +, F +), abnormal (AF) and absent (F + -, F -). After the first survey, each participant performed a self-learning exercise using clips of the first survey. The follow-up survey was conducted three months after the first survey. The median CAR of the first survey was 65% in certified assessors and 50% in noncertified assessors. The median CARs of certified assessors were significantly higher than that of noncertified assessors for all clips and for normal FMs and AF clips (p < 0.01). After 3 months of self-learning exercise the CARs in each judgement type improved in 28 follow-up survey participants. Their median CAR improved from 60% in the first survey to 84% in the follow-up survey. To practise general movements assessment (GMA), course certification is required. The self-learning exercise with the confirmed judgement FMs clips may be effective for improving the ability of FMs judgement
Statistical Mechanics of Self--Gravitating System : Cluster Expansion Method
We study statistical mechanics of the self--gravitating system applying the
cluster expansion method developed in solid state physics. By summing infinite
series of diagrams, we derive a complex free energy whose imaginary part is
related to the relaxation time of the system. Summation of another series
yields two--point correlation function whose correlation length is essentially
given by the Jeans wavelength of the system.Comment: 4 pages including 2 eps figures, RevTe
Introduction: Immersed in Lithics
The idea of holding a conference to discuss how we can explore what affects our approaches to, and understanding of, lithic artefacts and their analysis emerged from a hands-on workshop entitled Northern Knap-in in November 2014. In that workshop we wanted to explore how prehistoric people in the north of England, which is perceived by many as being a (lithic)resource-poor region, might have adapted to the lack of good quality flint and chert for tool manufacture and so we experimented with the working of non-flint raw materials. Many things emerged from that day including how the experimental knapping of materials other than flint allowed us to think outside the conventional box, and how communal knapping and grinding demonstrated some of the different ways that people interacted and adapted to each other’s rhythm when making artefacts. We were also struck (excuse the pun) by how much non-lithic specialists contributed to the questions we raise in lithic analysis. This brought home to us the importance of finding other, sometimes non- conventional, ways in which we can engage with the past. This eventually led to the Immersed in Lithics Conference in February 2016
Origin of scaling structure and non-gaussian velocity distribution in self-gravitating ring model
Fractal structures and non-Gaussian velocity distributions are characteristic
properties commonly observed in virialized self-gravitating systems such as
galaxies or interstellar molecular clouds. We study the origin of these
properties using the one-dimensional ring model which we newly propose in this
paper. In this simple model, particles are moving, on a circular ring fixed
in the three dimensional space, with mutual interaction of gravity. This model
is suitable for accurate symplectic integration method by which we find the
phase transition in this system from extended-phase to collapsed-phase through
an interesting phase (\halo-phase) which has negative specific heat. In this
intermediate energy scale, there appear scaling properties, non-thermal and
non-Gaussian velocity distributions. In contrast, these peculiar properties are
never observed in other \gas and \core phases. Particles in each phase have
typical time scales of motion determined by the cutoff length , the ring
radius and the total energy . Thus all relaxation patterns of the system
are determined by these three time scales.Comment: 21pages,11figure
Successful Extracorporeal Life Support for Life-threatening Hypercapnia with Bronchiolitis Obliterans after Allogeneic Hematopoietic Stem Cell Transplantation
Bronchiolitis obliterans (BO) is a disease with a poor prognosis, and a key factor that limits long-term survival after allogeneic hematopoietic stem cell transplantation (HSCT). We here report a case of a 31-year woman with acute lymphatic leukemia, which was treated by chemotherapy and HSCT, and consequently developed BO 2 years after HSCT. A non-tuberculous mycobacterial infection occurred and showed gradual exacerbation. She started taking anti-mycobacterial drugs, but lost appetite, felt tired and finally lost consciousness one month after beginning medication. Arterial blood gas revealed marked hypercapnia. Using extracorporeal life support (ECLS), the carbon dioxide concentration was reduced and her consciousness recovered. To our knowledge, this is the first case in which ECLS was successfully used for hypercapnia in a patient with BO
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