- Proceedings of the National Academy of Sciences of the United States of America
- Published about 5 years ago
The production of purposely made painted or engraved designs on cave walls-a means of recording and transmitting symbolic codes in a durable manner-is recognized as a major cognitive step in human evolution. Considered exclusive to modern humans, this behavior has been used to argue in favor of significant cognitive differences between our direct ancestors and contemporary archaic hominins, including the Neanderthals. Here we present the first known example of an abstract pattern engraved by Neanderthals, from Gorham’s Cave in Gibraltar. It consists of a deeply impressed cross-hatching carved into the bedrock of the cave that has remained covered by an undisturbed archaeological level containing Mousterian artifacts made by Neanderthals and is older than 39 cal kyr BP. Geochemical analysis of the epigenetic coating over the engravings and experimental replication show that the engraving was made before accumulation of the archaeological layers, and that most of the lines composing the design were made by repeatedly and carefully passing a pointed lithic tool into the grooves, excluding the possibility of an unintentional or utilitarian origin (e.g., food or fur processing). This discovery demonstrates the capacity of the Neanderthals for abstract thought and expression through the use of geometric forms.
The manufacture of geometric engravings is generally interpreted as indicative of modern cognition and behaviour. Key questions in the debate on the origin of such behaviour are whether this innovation is restricted to Homo sapiens, and whether it has a uniquely African origin. Here we report on a fossil freshwater shell assemblage from the Hauptknochenschicht (‘main bone layer’) of Trinil (Java, Indonesia), the type locality of Homo erectus discovered by Eugène Dubois in 1891 (refs 2 and 3). In the Dubois collection (in the Naturalis museum, Leiden, The Netherlands) we found evidence for freshwater shellfish consumption by hominins, one unambiguous shell tool, and a shell with a geometric engraving. We dated sediment contained in the shells with (40)Ar/(39)Ar and luminescence dating methods, obtaining a maximum age of 0.54 ± 0.10 million years and a minimum age of 0.43 ± 0.05 million years. This implies that the Trinil Hauptknochenschicht is younger than previously estimated. Together, our data indicate that the engraving was made by Homo erectus, and that it is considerably older than the oldest geometric engravings described so far. Although it is at present not possible to assess the function or meaning of the engraved shell, this discovery suggests that engraving abstract patterns was in the realm of Asian Homo erectus cognition and neuromotor control.
Depth of interaction (DOI) information is indispensable to improve sensitivity and spatial resolution of positron emission tomography (PET) systems especially for small field-of-view PET such as small animal PET. In this work, we proposed a more practical X'tal cube with the two-sided readout detector, which was made of crystal bars segmented in the height direction only by using SSLE technique. We developed two types of prototype detectors with a 3 mm cubic segment and a 1.5 mm cubic segment by using 3×3×20 mm3 and 1.5×1.5×20 mm3 crystal bars segmented into 7 and 13 DOI segments, respectively, using the SSLE technique. First, performance of the detector composed of one crystal bar with different DOI segments and two thorough silicon via (TSV) multi-pixel photon counters (MPPCs) as readout at both ends of the crystal bar were. Then, performance evaluation was carried out for a 4×4 crystal array of 3×3×20 mm3 with 7 DOI segments and an 8×8 crystal array of 1.5×1.5×20 mm3 with 13 DOI segments. Each readout included a 4×4 channel of the 3×3 mm2 active area TSV MPPCs. All the segments in the 4×4 array were identified very clearly when there was air between the crystal bars. The optimization was performed for the 8×8 array by inserting reflectors partially between the crystal bars. The mean energy resolutions at the 511 keV photo peak for the 4×4 array with air between the crystal bars and for the 8×8 array with partial reflectors between the crystal bars were 10.1% ± 0.3% and 10.8% ± 0.8%, respectively. Timing resolution of 783 ± 36 ps and 1.14 ± 0.22 ns were obtained for the detectors composed of the 4×4 array and the 8×8 array with partial reflectors, respectively. Practical X'tal cubes with 3 mm and 1.5 mm DOI resolutions and two-sided readout were developed.
In this study, a low-cost microfluidic device from polymethyl methacrylate was fabricated by laser engraving technique. The device is consisted of a central chip unit with an aligned microchannel. Both sides of the engraved microchannel were sandwiched by two synthesized sheets from polyamide/titania (PA/TiO2) hollow nanofibers as extractive phases. The inlet and outlet of the device were connected to the polyether ether ketone tubes, while a peristaltic pump was used to deliver both sample and desorbing solvent through the microchannel. The recorded scanning electron microscopy images from the surface of the synthesized PA/TiO2 nanofibers, exhibit a good degree of homogeneity and porosity throughout their structures. Also, the presence of titanium was indicated by the energy dispersive X-ray analysis, while the recorded Fourier transform infrared spectra confirmed their chemical structures. The addition of titania in the composition of polyamide nanofibers, not only improved the mechanical stability of the extractive phase but also enhanced its extraction capability. The major parameters associated with the extraction performance were studied and eventually the method was validated by the use of a gas chromatography-mass spectrometry. The limits of detection for the selected triazines were between 0.01 and 0.03ngmL(-1), while the limits of quantification ranged from 0.04 to 0.1ngmL(-1). In addition, the interday and intraday reproducibility (RSD%) were lower than 6.6% (n=3). The calibration graph for atrazine was linear in the range of 0.2-50ngmL(-1) while two linear ranges for ametryn and terbutryn (0.1-10 and 20-500ngmL(-1)) were achieved. Relative recoveries were between 89 and 98% with the regression coefficient range of 0.9969-0.9991.
Medical identification jewellery can convey vital information to emergency responders, but mistakes and ambiguity may lead to misdiagnosis and morbidity. We performed a review of relevant articles retrieved from Pubmed(®) , Embase(®) and Scopus(®) and Google UK Inc. to investigate the commercial availability and issuance of these products. From 84 identified studies, we shortlisted 74 for review. The Google search retrieved 1,090,000 results within 0.57 s (January 2017). We explored 32 websites selling medical alert jewellery in the first five pages of these results. We found that patients themselves are currently responsible for the engraved wording on medical alert jewellery, with no mandatory physician checks. The accuracy and appropriateness of this information may thus vary. In the absence of national guidance in the UK, we suggest that there should be a list of specific indications warranting their use, a requirement for regular review of information, and clarity around the level of physician input into the engraving chosen. We discuss the potential benefits vs. risks of wearing medical alert jewellery and clarify the limitations of medical teams' responsibilities in relation to patients found to be wearing them.
Self-folding or micro-origami technologies are actively investigated as a novel manufacturing process to fabricate three-dimensional macro/micro-structures. In this paper, we present a simple process to produce a self-folding structure with a biaxially oriented polystyrene sheet (BOPS) or Shrinky Dinks. A BOPS sheet is known to shrink to one-third of its original size in plane, when it is heated above 160 °C. A grid pattern is engraved on one side of the BOPS film with a laser engraver to decrease the thermal shrinkage of the engraved side. The thermal shrinkage of the non-engraved side remains the same and this unbalanced thermal shrinkage causes folding of the structure as the structure shrinks at high temperature. We investigated the self-folding mechanism and characterized how the grid geometry, the grid size, and the power of the laser engraver affect the bending curvature. The developed fabrication process to locally modulate thermomechanical properties of the material by engraving the grid pattern and the demonstrated design methodology to harness the unbalanced thermal shrinkage can be applied to develop complicated self-folding macro/micro structures.
The aim of this study was to compare the shear bond strength (SBS), enamel surface characteristics, and the adhesive remnant index (ARI) scores of different etching methods.
We propose a novel scintillation detector design for positron emission tomography (PET), which has depth of interaction (DOI) capability and uses a single-ended readout scheme. The DOI detector contains a pair of crystal bars segmented using sub-surface laser engraving (SSLE). The two crystal bars are optically coupled to each other at their top segments and are coupled to two photo-sensors at their bottom segments. Initially, we evaluated the performance of different designs of single crystal bars coupled to photomultiplier tubes at both ends. We found that segmentation by SSLE results in superior performance compared to the conventional method. As the next step, we constructed a crystal unit composed of a 3 × 3 × 20 mm(3) crystal bar pair, with each bar containing four layers segmented using the SSLE. We measured the DOI performance by changing the optical conditions for the crystal unit. Based on the experimental results, we then assessed the detector performance in terms of the DOI capability by evaluating the position error, energy resolution, and light collection efficiency for various crystal unit designs with different bar sizes and a different number of layers (four to seven layers). DOI encoding with small position error was achieved for crystal units composed of a 3 × 3 × 20 mm(3) LYSO bar pair having up to seven layers, and with those composed of a 2 × 2 × 20 mm(3) LYSO bar pair having up to six layers. The energy resolution of the segment in the seven-layer 3 × 3 × 20 mm(3) crystal bar pair was 9.3%-15.5% for 662 keV gamma-rays, where the segments closer to the photo-sensors provided better energy resolution. SSLE provides high geometrical accuracy at low production cost due to the simplicity of the crystal assembly. Therefore, the proposed DOI detector is expected to be an attractive choice for practical small-bore PET systems dedicated to imaging of the brain, breast, and small animals.
Oracle Bone Inscriptions in the Shang dynasty (1600-1046 BC) are the earliest well-developed writing forms of the Chinese character system, and their carving techniques have not been studied by tool marks analysis with microscopy. In this study, a digital microscope with three-dimensional surface reconstruction based on extended depth of focus technology was used to investigate tool marks on the surface of four pieces of oracle bones excavated at the eastern area of Huayuanzhuang, Yinxu site(ca., 1319-1046 BC), the last capital of the Shang dynasty, Henan province, China. The results show that there were two procedures to carve the characters on the analyzed tortoise shells. The first procedure was direct carving. The second was “outlining design,” which means to engrave a formal character after engraving a draft with a pointed tool. Most of the strokes developed by an engraver do not overlap the smaller draft, which implies that the outlining design would be a sound way to avoid errors such as wrong and missing characters. The strokes of these characters have different shape at two ends and variations on width and depth of the grooves. Moreover, the bottom of the grooves is always rugged. Thus, the use of rotary wheel-cutting tools could be ruled out. In most cases, the starting points of the strokes are round or flat while the finishing points are always pointed. Moreover, the strokes should be engraved from top to bottom. When vertical or horizontal strokes had been engraved, the shell would be turned about 90 degrees to engrave the crossed strokes from top to bottom. There was no preferred order to engrave vertical or horizontal strokes. Since both sides of the grooves of the characters are neat and there exists no unorganized tool marks, then it is suggested that some sharp tools had been used for engraving characters on the shells. Microsc. Res. Tech., 2016. © 2016 Wiley Periodicals, Inc.
Glass is one of the most convenient materials for the development of microfluidic devices. However, most fabrication protocols require long processing times and expensive facilities. As a convenient alternative, polymeric materials have been extensively used due their lower cost and versatility. Although CO2 laser ablation has been used for fast prototyping on polymeric materials, it can’t be applied to glass devices because the local heating causes thermal stress and results in extensive cracking. A few papers have shown the ablation of channels or thin holes (used as reservoirs) on glass but the process is still far away from yielding functional glass microfluidic devices. To address these shortcomings, this communication describes a simple method to engrave glass-based capillary electrophoresis devices using standard (1 mm-thick) microscope glass slides. The process uses a sacrificial layer of wax as heat sink and enables the development of both channels (with semicircular shape) and pass-through reservoirs. Although microscope images showed some small cracks around the channels (that became irrelevant after sealing the engraved glass layer to PDMS) the proposed strategy is a leap forward in the application of the technology to glass. In order to demonstrate the capabilities of the approach, the separation of dopamine, catechol and uric acid was accomplished in less than 100 s. This article is protected by copyright. All rights reserved.