2,970 research outputs found

    Recursive Compressed Sensing

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    We introduce a recursive algorithm for performing compressed sensing on streaming data. The approach consists of a) recursive encoding, where we sample the input stream via overlapping windowing and make use of the previous measurement in obtaining the next one, and b) recursive decoding, where the signal estimate from the previous window is utilized in order to achieve faster convergence in an iterative optimization scheme applied to decode the new one. To remove estimation bias, a two-step estimation procedure is proposed comprising support set detection and signal amplitude estimation. Estimation accuracy is enhanced by a non-linear voting method and averaging estimates over multiple windows. We analyze the computational complexity and estimation error, and show that the normalized error variance asymptotically goes to zero for sublinear sparsity. Our simulation results show speed up of an order of magnitude over traditional CS, while obtaining significantly lower reconstruction error under mild conditions on the signal magnitudes and the noise level.Comment: Submitted to IEEE Transactions on Information Theor

    Fundamental properties of solar-like oscillating stars from frequencies of minimum Δν\Delta \nu : II. Model computations for different chemical compositions and mass

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    The large separations between the oscillation frequencies of solar-like stars are measures of stellar mean density. The separations have been thought to be mostly constant in the observed range of frequencies. However, detailed investigation shows that they are not constant, and their variations are not random but have very strong diagnostic potential for our understanding of stellar structure and evolution. In this regard, frequencies of the minimum large separation are very useful tools. From these frequencies, in addition to the large separation and frequency of maximum amplitude, Y\i ld\i z et al. recently have developed new methods to find almost all the fundamental stellar properties. In the present study, we aim to find metallicity and helium abundances from the frequencies, and generalize the relations given by Y\i ld\i z et al. for a wider stellar mass range and arbitrary metallicity (ZZ) and helium abundance (YY). We show that the effect of metallicity is { significant} for most of the fundamental parameters. For stellar mass, for example, the expression must be multiplied by (Z/Z_{\sun})^{0.12}. For arbitrary helium abundance, M \propto (Y/Y_{\sun})^{0.25} . Methods for determination of ZZ and YY from pure asteroseismic quantities are based on amplitudes (differences between maximum and minimum values of \Dnu) in the oscillatory component in the spacing of oscillation frequencies. Additionally, we demonstrate that the difference between the first maximum and the second minimum is very sensitive to ZZ. It also depends on νmin1/νmax\nu_{\rm min1}/\nu_{\rm max} and small separation between the frequencies. Such a dependence leads us to develop a method to find ZZ (and YY) from oscillation frequencies. The maximum difference between the estimated and model ZZ values is about 14 per cent. It is 10 per cent for YY.Comment: 8 pages, 13 figures; published in MNRAS (2015

    Comparison of Gaia and asteroseismic distances

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    Asteroseismology provides fundamental properties (mass, radius and effective temperature) of solar-like oscillating stars using so-called scaling relations. These properties allow the computation of the asteroseismic distance of stars. We compare the asteroseismic distances with the recently released Gaia distances for 74 stars studied in Y{\i}ld{\i}z et al. There is a very good agreement between these two distances; for 64 of these stars, the difference is less than 10 per cent. However, a systematic difference is seen if we use the effective temperature obtained by spectroscopic methods; the Gaia distances are about 5 per cent greater than the asteroseismic distances.Comment: 4 pages, 4 figures, accepted by MNRA

    On the structure and evolution of planets and their host stars - effects of various heating mechanisms on the size of giant gas planets

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    It is already stated in the previous studies that the radius of the giant planets is affected by stellar irradiation. The confirmed relation between radius and incident flux depends on planetary mass intervals. In this study, we show that there is a single relation between radius and irradiated energy per gram per second (ll_-), for all mass intervals. There is an extra increase in radius of planets if ll_- is higher than 1100 times energy received by the Earth (ll_\oplus). This is likely due to dissociation of molecules. The tidal interaction as a heating mechanism is also considered and found that its maximum effect on the inflation of planets is about 15 per cent. We also compute age and heavy element abundances from the properties of host stars, given in the TEPCat catalogue (Southworth 2011). The metallicity given in the literature is as [Fe/H]. However, the most abundant element is oxygen, and there is a reverse relation between the observed abundances [Fe/H] and [O/Fe]. Therefore, we first compute [O/H] from [Fe/H] by using observed abundances, and then find heavy element abundance from [O/H]. We also develop a new method for age determination. Using the ages we find, we analyse variation of both radius and mass of the planets with respect to time, and estimate the initial mass of the planets from the relation we derive for the first time. According to our results, the highly irradiated gas giants lose 5 per cent of their mass in every 1 Gyr.Comment: 15 pages, 13 figures, 3 tables. Accepted by MNRA

    YOGURT; A NOVEL EXCIPIENT (WITH ITS LYSED BACTERIA, AMINO ACIDS, VITAMINS, FATTY ACIDS, AND MINERALS) FOR “TOPICAL DERMATOLOGICAL PRODUCTS” AND FOR “SKIN MICROBIOTA”

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    In recent years various Microbiomes (Skin, Gut Lumen) of the human body have attracted the attention of different research groups. In the meantime it has been shown that the conventional therapy of different diseases by making use of antibiotics and similar antibacterial treatments may disturb the harmony of the Skin Microbiome, resulting in dysbiosis. There are efforts of using “live” or “tyndallized (lysed)” probiotics in order to treat different diseases of the skin. It is also known that amino acids are one of the important key elements of the skin. In this paper, a hypothesis for the utilization of yogurt as an excipient for various topical dermatological products will be proposed. Yogurt contains significant amounts of; Probiotics (starter cultures), Amino Acids, Vitamins, Minerals and various Fatty Acids (saturated, monounsaturated and polyunsaturated). Besides, it has been shown that Antimicrobial Peptides (Bacteriocins) are also present in yogurt. Yogurt could eventually be used as an excipient for the production of various topical dermatological products in order to deliver some of the above-mentioned constituents to the Stratum Corneum (Skin) locally

    An anatomical study on the three-headed biceps brachii in human foetuses, and clinical relevance

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    The biceps brachii (BB) is as one of the most variable muscles in the human body in terms of number and morphology of its heads. The most frequent variation is the presence of a third head, which has been reported by several authors in different populations. Our aim was to find the occurrence of the supernumerary head of BB in Turkish foetuses. Out of the 24 upper limbs of the foetuses, two (8.33%) arms were found to have a three-headed BB. The variations were present unilaterally in the right arm of one male foetus and one female foetus. In one of the cases, the third head of BB originated from the anteromedial aspect of the humerus just distal to the insertion of the coracobrachilais, medial to the brachialis, and in the other the third head was a thin muscle bundle, which arose on the lateral side of the insertion of coracobrachialis and over the origin of the brachialis. Both of them were extended distally and joined the common tendon. The occasional presence of the three-headed BB in the foetuses observed in the present study was similar to those of adults reported in previous studies. In conclusion, these variations are not rare and are interesting not only to anatomists but also to orthopaedic surgeons, plastic surgeons, traumatologists, physiotherapists, doctors dealing with sports medicine, and radiologists. (Folia Morphol 2011; 70, 2: 116–120

    What can generic neural networks learn from a child's visual experience?

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    Young children develop sophisticated internal models of the world based on their egocentric visual experience. How much of this is driven by innate constraints and how much is driven by their experience? To investigate these questions, we train state-of-the-art neural networks on a realistic proxy of a child's visual experience without any explicit supervision or domain-specific inductive biases. Specifically, we train both embedding models and generative models on 200 hours of headcam video from a single child collected over two years. We train a total of 72 different models, exploring a range of model architectures and self-supervised learning algorithms, and comprehensively evaluate their performance in downstream tasks. The best embedding models perform at 70% of a highly performant ImageNet-trained model on average. They also learn broad semantic categories without any labeled examples and learn to localize semantic categories in an image without any location supervision. However, these models are less object-centric and more background-sensitive than comparable ImageNet-trained models. Generative models trained with the same data successfully extrapolate simple properties of partially masked objects, such as their texture, color, orientation, and rough outline, but struggle with finer object details. We replicate our experiments with two other children and find very similar results. Broadly useful high-level visual representations are thus robustly learnable from a representative sample of a child's visual experience without strong inductive biases.Comment: 26 pages, 14 figures, 3 tables; code & all pretrained models available from https://github.com/eminorhan/silicon-menageri

    Anatomical characteristics of the lingual foramen in ancient skulls: a cone beam computed tomography study in an Anatolian population

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    Background: The purpose of this study is to evaluate the anatomical features of lingual foramina and their bony canals in Anatolian ancient mandibles (9–10th century) by using cone beam computed tomography (CBCT). Materials and methods: Fifty-eight ancient dry mandibles were scanned with CBCT. Lingual foramina were grouped into midline, paramedian, posterior foramina and combination of these groups. Midline group was also classified according to internal surface of the mandible (gonial tubercles [GTs]). The incidence, vertical distance and diameter of lingual foramina were measured according to age groups and gender. Results: The incidence of the lingual foramen was 96.6%. Midline of the symphysis had the highest incidence (34.4%) of foramina (p < 0.05), followed by both midline and paramedian type (32.8%; p < 0.05). Classification in terms of GT represented class 3 as the most encountered group (28.6%). Number of foramina observed in the mandibles ranged from 0 to 6 with the incidence of 3.4% and 32.8%, respectively. The male and < 35 years groups presented larger measurement values in midline region (p < 0.05). Conclusions: Mandibular lingual foramina and bony canals are frequently present in ancient mandibles. When compared with modern subjects, similar findings are observed according to published literatures. CBCT is also proved to be an effective imaging modality in the detection of lingual foramina and canals in anthropological studies
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