2,536 research outputs found
Karyotyping human chromosomes by optical and X-ray ptychography methods
Sorting and identifying chromosomes, a process known as karyotyping, is widely used to detect changes in chromosome shapes and gene positions. In a karyotype the chromosomes are identified by their size and therefore this process can be performed by measuring macroscopic structural variables. Chromosomes contain a specific number of base pairs that linearly correlate with their size; therefore it is possible to perform a karyotype on chromosomes using their mass as an identifying factor. Here, we obtain the first images of chromosomes using the novel imaging method of ptychography. We can use the images to measure the mass of chromosomes and perform a partial karyotype from the results. We also obtain high spatial resolution using this technique with synchrotron source X-rays
Testing a priority-based queue model with Linux command histories
We study human dynamics by analyzing Linux history files. The goodness-of-fit
test shows that most of the collected datasets belong to the universality class
suggested in the literature by a variable-length queueing process based on
priority. In order to check the validity of this model, we design two tests
based on mutual information between time intervals and a mathematical
relationship known as the arcsine law. Since the previously suggested queueing
process fails to pass these tests, the result suggests that the modelling of
human dynamics should properly consider the statistical dependency in the
temporal dimension.Comment: 17 pages, 17 figure
Gas-induced segregation in Pt-Rh alloy nanoparticles observed by in-situ Bragg coherent diffraction imaging
Bimetallic catalysts can undergo segregation or redistribution of the metals
driven by oxidizing and reducing environments. Bragg coherent diffraction
imaging (BCDI) was used to relate displacement fields to compositional
distributions in crystalline Pt-Rh alloy nanoparticles. 3D images of internal
composition showed that the radial distribution of compositions reverses
partially between the surface shell and the core when gas flow changes between
O2 and H2. Our observation suggests that the elemental segregation of
nanoparticle catalysts should be highly active during heterogeneous catalysis
and can be a controlling factor in synthesis of electrocatalysts. In addition,
our study exemplifies applications of BCDI for in situ 3D imaging of internal
equilibrium compositions in other bimetallic alloy nanoparticles
Real-time sparse-sampled Ptychographic imaging through deep neural networks
Ptychography has rapidly grown in the fields of X-ray and electron imaging
for its unprecedented ability to achieve nano or atomic scale resolution while
simultaneously retrieving chemical or magnetic information from a sample. A
ptychographic reconstruction is achieved by means of solving a complex inverse
problem that imposes constraints both on the acquisition and on the analysis of
the data, which typically precludes real-time imaging due to computational cost
involved in solving this inverse problem. In this work we propose PtychoNN, a
novel approach to solve the ptychography reconstruction problem based on deep
convolutional neural networks. We demonstrate how the proposed method can be
used to predict real-space structure and phase at each scan point solely from
the corresponding far-field diffraction data. The presented results demonstrate
how PtychoNN can effectively be used on experimental data, being able to
generate high quality reconstructions of a sample up to hundreds of times
faster than state-of-the-art ptychography reconstruction solutions once
trained. By surpassing the typical constraints of iterative model-based
methods, we can significantly relax the data acquisition sampling conditions
and produce equally satisfactory reconstructions. Besides drastically
accelerating acquisition and analysis, this capability can enable new imaging
scenarios that were not possible before, in cases of dose sensitive, dynamic
and extremely voluminous samples
APLIKASI TEORI PERILAKU TERENCANA: NIAT MELAKUKAN PHYSICAL EXERCISE (LATIHAN FISIK) PADA REMAJA DI SURABAYA
Alasan utama untuk rnengangkat topik ini dalarn penelitian ia1ah penulis berrnaksud untuk rneneliti variabel-variabel yang rnelatarbelakangi perilaku physical exercise yang dilakukan remaja di Surabaya. Tujuannya, peneliti ingin rnenguji apakah ada hubungan antara attitude towards behavior (A TB), subjective norm (SN), dan perceived behavioral control (PBC), baik secara bersama-sama maupun secara parsial, dengan niat berperilaku physical exercise (latihan fisik) pada remaja di Surabaya. Metode angket digunakan dalarn penelitian ini, rnenggunakan teknik penskalaan sernantik diferensial. Rernaja baik pria dan wanita (N=336) di kota Surabaya berpartisipasi dalarn penelitian ini. Hasil uji hipotesis rnenujukkan bahwa : {a). Terdapat hubungan yang signifikan antara ATB, SN, dan PBC, secara bersarna-sarna terhadap niat rnelakukan Physical exersice pada remaja (F = 14.233; p = 0,000). Hasil korelasi parsial menunjukkan ATB, dan SN menjadi prediktor paling kuat terhadap niat melaku.kan Physical Exercise, sedangkan PBC tidak
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