julilili42/papers huggingface dataset:
Micro XRF
2017-08-30

Chapter 41 Micro XRF Susan M. Mentzer, Susan M. Mentzer Institute for Archaeological Sciences, University of Tübingen, Tübingen, Germany School of Anthropology, University of Arizona, Tucson, USA Senckenberg Centre for Human Evolution and Paleoenvironment, University of Tübingen, Tübingen, GermanySearch for more papers by this author Susan M. Mentzer, Susan M. Mentzer Institute for Archaeological Sciences, University of Tübingen, Tübingen, Germany School of Anthropology, University of Arizona, Tucson, USA Senckenberg Centre for Human Evolution and Paleoenvironment, University of Tübingen, Tübingen, GermanySearch for more papers by this author Book Editor(s):Dr. Cristiano Nicosia, Dr. Cristiano Nicosia Centre de Recherches en Archéologie et Patrimoine, Université Libre de Bruxelles, BelgiumSearch for more papers by this authorEm. Prof. Dr. Georges Stoops, Em. Prof. Dr. Georges Stoops Vakgroep Geologie, Faculteit Wetenschappen, Universiteit Gent, BelgiumSearch for more papers by this author First published: 30 August 2017 https://doi.org/10.1002/9781118941065.ch41Citations: 10 AboutPDFPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShareShare a linkShare onFacebookTwitterLinked InRedditWechat Summary Microscopic X-ray fluorescence spectroscopy (Micro-XRF) shows much promise for studies that integrate micromorphological observations from thin sections with data regarding elemental composition of different sediments and materials. The strengths of the technique include minimal sample preparation, and its suitability for analysis of different portions of micromorphology blocks including large slabs. Laboratory-grade micro-XRF instruments differ from traditional XRF instruments in their X-ray focusing optics and sample chamber configurations. Researchers in this field emphasize in particular the strength of combining petrography with micro-XRF data, an approach that has direct implications for archaeological micromorphology. Micro-XRF analyses have been conducted successfully directly on resin-impregnated archaeological sediment blocks. Micro-XRF applications in terrestrial sedimentology, soil science and archaeology that link elemental measurements with micromorphological or other petrographic analyses are thus far rather limited. A brief overview of the few studies outside of archaeology reveals several applications in understanding soil forming processes. Citing Literature Archaeological Soil and Sediment Micromorphology RelatedInformation
X‐ray Microdiffraction
2017-08-30

X-ray diffraction (XRD) is used for studying the crystal structure of inorganic and organic substances. In geosciences, the most common application of XRD is in the analysis of powder samples. A typical X-ray powder diffractometer consists of a water-cooled X-ray tube, a detector for recording the intensities of X-rays scattered by the analysed sample, and a goniometer that controls the angle between the X-ray tube, sample and detector. For samples in thin section, or for very small sample amounts, the more appropriate technique is a variety of XRD known as X-ray microdiffraction (μ-XRD). In μ-XRD, the analytical area is variable and depends on the optics of the instrument and the sampling parameters. The output of a μ-XRD measurement is similar to that of classical XRD. If a two-dimensional detector is used (μ-XRD2), a certain number of overlapping diffraction images is produced depending on size of the detector and the °2θ-range to be analysed.
Reflected Light
2017-08-30

Reflected light microscopy is used mainly in the petrographic analysis of thin sections in archaeological contexts to identify and classify the organic components. The methodology used to study the organic components is that of organic petrology, which was developed principally from the years 1963 to 1995 for the petrographic study of peat, brown coal, hard coals, source rocks and other rocks containing organic carbon. To carry out the petrographic analyses, a reflected light microscope photometer equipped for fluorescence examination with the capability of switching to white light illumination and setup with oil immersion objectives 20x and 50x is used. Reflectance analysis is an important tool in organic petrology and is employed to determine the rank of coal and the maturation level of the sedimentary organic matter. Methods of organic petrology can be used for a wide range of archaeological applications.
Isotope Mass Spectrometry (On Microdrilled Powders)
2017-08-30

Many analytical techniques – beyond optical petrography – can be applied to micromorphological samples, which include thin sections and resin-impregnated sediment blocks. A relatively recent development, the use of stable isotope mass spectrometry on powders drilled from archaeological sediment blocks was first reported in Mentzer & Quade. Isotopic analysis of the resulting powder proceeds via a mass spectrometer. This chapter describes the basic analytical procedure for measurements of stable isotopic ratios of carbon and oxygen in bulk samples of carbonates. The microdrilling technique differs very little from the standard analytical procedure on bulk samples. Microdrilling as a method of subsample extraction has been applied widely in studies of speleothems. Applications of isotopic analysis to calcareous archaeological materials are also numerous but are typically conducted on loose samples, which limits the ability of micromorphologists to provide information about the context or conditions of preservation.
Secondary growth as a determinant of plant shape and form
2017-08-31

Plants are the primary producers of biomass on earth. As an almost stereotypic feature, higher plants generate continuously growing bodies mediated by the activity of different groups of stem cells, the meristems. Shoot and root thickening is one of the fundamental growth processes determining form and function of these bodies. Mediated by a group of cylindrical meristems located below organ surfaces, vascular and protective tissues are continuously generated in a highly plastic manner, a competence essential for the survival in an ever changing environment. Acknowledging the fundamental role of this process, which is overall designated as secondary growth, we discuss in this review our current knowledge about the evolution and molecular regulation of the vascular cambium. The cambium is the meristem responsible for the formation of wood and bast, the two types of vascular tissues important for long-distance transport of water and assimilates, respectively. Although regulatory patterns are only beginning to emerge, we show that cambium activity represents a highly rewarding model for studying cell fate decisions, tissue patterning and differentiation, which has experienced an outstanding phylogenetic diversification.
Platelet-mediated shedding of NKG2D ligands impairs NK cell immune-surveillance of tumor cells
2017-08-31

Platelets promote metastasis, among others by coating cancer cells traveling through the blood, which results in protection from NK cell immune-surveillance. The underlying mechanisms, however, remain to be fully elucidated. Here we report that platelet-coating reduces surface expression of NKG2D ligands, in particular MICA and MICB, on tumor cells, which was mirrored by enhanced release of their soluble ectodomains. Similar results were obtained upon exposure of tumor cells to platelet-releasate and can be attributed to the sheddases ADAM10 and ADAM17 that are detectable on the platelet surface and in releasate following activation and at higher levels on platelets of patients with metastasized lung cancer compared with healthy controls. Platelet-mediated NKG2DL-shedding in turn resulted in impaired "induced self" recognition by NK cells as revealed by diminished NKG2D-dependent lysis of tumor cells. Our results indicate that platelet-mediated NKG2DL-shedding may be involved in immune-evasion of (metastasizing) tumor cells from NK cell reactivity.
Comparative effectiveness of antiepileptic drugs in patients with mesial temporal lobe epilepsy with hippocampal sclerosis
2017-08-31

Summary Objective Mesial temporal lobe epilepsy with hippocampal sclerosis ( MTLE ‐ HS ) is a common epilepsy syndrome that is often poorly controlled by antiepileptic drug ( AED ) treatment. Comparative AED effectiveness studies in this condition are lacking. We report retention, efficacy, and tolerability in a cohort of patients with MTLE ‐ HS . Methods Clinical data were collected from a European database of patients with epilepsy. We estimated retention, 12‐month seizure freedom, and adverse drug reaction ( ADR ) rates for the 10 most commonly used AED s in patients with MTLE ‐ HS . Results Seven hundred sixty‐seven patients with a total of 3,249 AED trials were included. The highest 12‐month retention rates were observed with carbamazepine (85.9%), valproate (85%), and clobazam (79%). Twelve‐month seizure freedom rates varied from 1.2% for gabapentin and vigabatrin to 11% for carbamazepine. Response rates were highest for AED s that were prescribed as initial treatment and lowest for AED s that were used in a third or higher instance. ADR s were reported in 47.6% of patients, with the highest rates observed with oxcarbazepine (35.7%), topiramate (30.9%), and pregabalin (27.4%), and the lowest rates with clobazam (6.5%), gabapentin (8.9%), and lamotrigine (16.6%). The most commonly reported ADR s were lethargy and drowsiness, dizziness, vertigo and ataxia, and blurred vision and diplopia. Significance Our results did not demonstrate any clear advantage of newer versus older AED s. Our results provide useful insights into AED retention, efficacy, and ADR rates in patients with MTLE ‐ HS .
Are baboons learning "orthographic" representations? Probably not
2017-08-31

The ability of Baboons (papio papio) to distinguish between English words and nonwords has been modeled using a deep learning convolutional network model that simulates a ventral pathway in which lexical representations of different granularity develop. However, given that pigeons (columba livia), whose brain morphology is drastically different, can also be trained to distinguish between English words and nonwords, it appears that a less species-specific learning algorithm may be required to explain this behavior. Accordingly, we examined whether the learning model of Rescorla and Wagner, which has proved to be amazingly fruitful in understanding animal and human learning could account for these data. We show that a discrimination learning network using gradient orientation features as input units and word and nonword units as outputs succeeds in predicting baboon lexical decision behavior-including key lexical similarity effects and the ups and downs in accuracy as learning unfolds-with surprising precision. The models performance, in which words are not explicitly represented, is remarkable because it is usually assumed that lexicality decisions, including the decisions made by baboons and pigeons, are mediated by explicit lexical representations. By contrast, our results suggest that in learning to perform lexical decision tasks, baboons and pigeons do not construct a hierarchy of lexical units. Rather, they make optimal use of low-level information obtained through the massively parallel processing of gradient orientation features. Accordingly, we suggest that reading in humans first involves initially learning a high-level system building on letter representations acquired from explicit instruction in literacy, which is then integrated into a conventionalized oral communication system, and that like the latter, fluent reading involves the massively parallel processing of the low-level features encoding semantic contrasts.
Multiband photometry and spectroscopy of an all-sky sample of bright white dwarfs
2017-08-31

The upcoming NASA Transiting Exoplanet Survey Satellite (TESS) will obtain space-based uninterrupted light curves for a large sample of bright white dwarfs distributed across the entire sky, providing a very rich resource for asteroseismological studies and the search for transits from planetary debris. We have compiled an all-sky catalogue of ultraviolet, optical and infrared photometry as well as proper motions, which we propose as an essential tool for the preliminary identification and characterization of potential targets. We present data for 1864 known white dwarfs and 305 high-probability white dwarf candidates brighter than 17 mag. We describe the spectroscopic follow-up of 135 stars, of which 82 are white dwarfs and 25 are hot subdwarfs. The new confirmed stars include six pulsating white dwarf candidates (ZZ Cetis), and nine white dwarf binaries with a cool main-sequence companion. We identify one star with a spectroscopic distance of only 25 pc from the Sun. Around the time TESS is launched, we foresee that all white dwarfs in this sample will have trigonometric parallaxes measured by the ESA Gaia mission next year.
Ultrafast Charge Transfer and Upconversion in Zinc β‐Tetraaminophthalocyanine‐Functionalized PbS Nanostructures Probed by Transient Absorption Spectroscopy
2017-08-31

Abstract We functionalize PbS nanocrystals with the organic semiconductor Zn β‐tetraaminophthalocyanine to design a nanostructured solid‐state material with frequent organic–inorganic interfaces. By transient absorption and fluorescence spectroscopy, we investigate the optoelectronic response of this hybrid material under near‐infrared excitation to find efficient charge transfer from the nanocrystals to the molecules. We demonstrate that the material undergoes cooperative sensitization of two nanocrystals followed by photon upconversion and singlet emission of the organic semiconductor. The upconversion efficiency resembles that of comparable systems in solution, which we attribute to the large amount of interfaces present in this solid‐state film. We anticipate that this synthetic strategy has great prospects for increasing the open‐circuit voltage in PbS nanocrystal‐based solar cells.
Basic parameters of the helium-accreting X-ray bursting neutron star in 4U 1820−30
2017-08-31

The ultracompact low-mass X-ray binary 4U 1820-30 situated in the globular cluster NGC 6624 has an orbital period of only 11.4 min which likely implies a white dwarf companion. The observed X-ray bursts demonstrate a photospheric radius expansion phase and therefore are believed to reach the Eddington luminosity allowing us to estimate the mass and the radius of the neutron star (NS) in this binary. Here we re-analyse all Rossi X-ray Timing Explorer observations of the system and confirm that almost all the bursts took place during the hard persistent state of the system. This allows us to use the recently developed direct cooling tail method to estimate the NS mass and radius. However, because of the very short, about a second, duration of the cooling tail phases that can be described by the theoretical atmosphere models, the obtained constraints on the NS radius are not very strict. Assuming a pure helium NS atmosphere we found that the NS radius is in the range 10-12 km, if the NS mass is below 1.7 , and in a wider range of 8-12 km for a higher 1.7-2.0 NS mass. The method also constrains the distance to the system to be 6.5 0.5 kpc, which is consistent with the distance to the cluster. For the solar composition atmosphere, the NS parameters are in strong contradiction with the generally accepted range of possible NS masses and radii.
Dynamics of multistable biological motion perception
2017-08-31

The dynamic stability of percepts has been extensively studied in low-level motion (Hock et al. 2003, 1996). A manifestation of dynamic stability is the perceptual hysteresis shown for a pair of mutually exclusive motion stimuli. So far hysteresis effects have not been investigated in biological motion perception. Its measurement requires a parameter that controls the relative bias of perception for the two alternatives. We developed such a stimulus for biological motion perception and investigated dynamic stability. METHODS: Our stimulus is based on the fact that body motion perception from two-dimensional movies can be bistable (Vanrie et al. 2004), alternating between two different percepts. We developed a new stimulus by random sampling two shaded volumetric walkers covered with 1050 circular discs. The fraction of discs drawn from either walker is a hysteresis parameter that allows to vary gradually the preference for two perceived walking directions. We realized two experiments: I. Measurement of the times before the first perceptual switch as function of the hysteresis parameter. II. Measurement of a hysteresis loop, varying the hysteresis parameter gradually up and down. This experiment adapted the Modified Method of Limits by (Hock et al. 1993). RESULTS: Experiment I shows that, dependent on the hysteresis parameter, the new stimulus can induce both an unambiguous perception of walking direction and perceptual bistability. The average switching time is smallest if both percepts are equally likely and it depends systematically on the hysteresis parameter (p < 10-15). Experiment II measured the percept probabilities as function of the hysteresis parameter. These probabilities are significantly dependent on previous values of the parameter (i.e. whether it was increasing or decreasing), implying perceptual hysteresis (p < 0.01). CONCLUSION: We demonstrated that body motion perception, like low-level motion perception, shows indicators of dynamic multi-stability. Meeting abstract presented at VSS 2017
Perception of others' body sizes is predicted by own body size
2017-08-31

Previous research demonstrated that estimates of others' body sizes are biased towards the average body size in the population (Cornelissen, Gledhill, Cornelissen & Tovée, 2016). Bodies in the environment not only influence the internal reference of what is perceived as average or "normal", but also play an essential role in self-body size evaluation via social comparison (Cattarin, Thompson, Thomas & Williams, 2000). In two psychophysical experiments, we asked whether there is also an influence of own body size on the perception of others' body sizes. For Experiment 1, four biometric female avatars with a body mass index (BMI) of 15, 25, 35, and 45 were generated, and then their weight was altered (± 5, ±10, ±15, and ±20% BMI change) based on a statistical body model. For each of the avatar series, female participants spanning the BMI range memorized what the avatar's body looked like and then responded for the presented bodies varying in weight whether it was the same as the one memorized. Results showed no influence of participants' BMI on the accuracy of body size estimates, but sensitivity to weight changes was highest for bodies close to one's own BMI. In Experiment 2, we examined whether this effect was driven by memory or perceptual factors. Specifically, in a 2-alternative forced choice discrimination task, two bodies were presented simultaneously using the same BMI categories as in Experiment 1. If participants' body size influences sensitivity during simultaneous presentation, it would suggest that the effect found in Experiment 1 is not due to a better memorization of bodies that are close to one's own body size. Again, sensitivity to differences in body weight was highest for bodies close to one's own BMI. These results suggest that our own body size influences our perceptual ability to discriminate the sizes of other's bodies. Meeting abstract presented at VSS 2017
Of Human Observers and Deep Neural Networks: A Detailed Psychophysical Comparison
2017-08-31

Deep Neural Networks (DNNs) have recently been put forward as computational models for feedforward processing in the human and monkey ventral streams. Not only do they achieve human-level performance in image classification tasks, recent studies also found striking similarities between DNNs and ventral stream processing systems in terms of the learned representations (e.g. Cadieu et al., 2014, PLOS Comput. Biol.) or the spatial and temporal stages of processing (Cichy et al., 2016, arXiv). In order to obtain a more precise understanding of the similarities and differences between current DNNs and the human visual system, we here investigate how classification accuracies depend on image properties such as colour, contrast, the amount of additive visual noise, as well as on image distortions resulting from the Eidolon Factory. We report results from a series of image classification (object recognition) experiments on both human observers and three DNNs (AlexNet, VGG-16, GoogLeNet). We used experimental conditions favouring single-fixation, purely feedforward processing in human observers (short presentation time of t = 200 ms followed by a high contrast mask); additionally, we used exactly the same images from 16 basic level categories for human observers and DNNs. Under non-manipulated conditions we find that DNNs indeed outperformed human observers (96.2% correct versus 88.5%; colour, full-contrast, noise-free images). However, human observers clearly outperformed DNNs for all of the image degrading manipulations: most strikingly, DNN performance severely breaks down with even small quantities of visual random noise. Our findings reinforce how robust the human visual system is against various image degradations, and indicate that there may still be marked differences in the way the human visual system and the three tested DNNs process visual information. We discuss which differences between known properties of the early and higher visual system and DNNs may be responsible for the behavioural discrepancies we find. Meeting abstract presented at VSS 2017
Towards matching peripheral appearance for arbitrary natural images using deep features
2017-08-31

Due to the structure of the primate visual system, large distortions of the input can go unnoticed in the periphery, and objects can be harder to identify. What encoding underlies these effects? Similarly to Freeman & Simoncelli (Nature Neuroscience, 2011), we developed a model that uses summary statistics averaged over spatial regions that increases with retinal eccentricity (assuming central fixation on an image). We also designed the averaging areas such that changing their scaling progressively discards more information from the original image (i.e. a coarser model produces greater distortions to original image structure than a model with higher resolution). Different from Freeman and Simoncelli, we use the features of a deep neural network trained on object recognition (the VGG-19; Simonyan & Zisserman, ICLR 2015), which is state-of-the art in parametric texture synthesis. We tested whether human observers can discriminate model-generated images from their original source images. Three images subtending 25 deg, two of which were physically identical, were presented for 200 ms each in a three-alternative temporal oddity paradigm. We find a model that, for most original images we tested, produces synthesised images that cannot be told apart from the originals despite producing significant distortions of image structure. However, some images were readily discriminable. Therefore, the model has successfully encoded necessary but not sufficient information to capture appearance in human scene perception. We explore what image features are correlated with discriminability on the image (which images are harder than others?) and pixel (where in an image is the hardest location?) level. While our model does not produce "metamers", it does capture many features important for the appearance of arbitrary natural images in the periphery. Meeting abstract presented at VSS 2017