Моделирование сорбционных процессов на твердофазных ионообменниках

Объектом исследования являются характеристики ионообменных материалов, влияющие на процессы очистки технологических растворов от растворенных в них соединений. Цель работы – определить влияние селективных свойств ионообменного материала, кинетических характеристик, а также метода осуществления процесса на эффективность разделения ионов щелочных и щелочноземельных элементов В процессе выполнения работы изучались физико-химические характеристики ионообменного материала, определялись кинетические, гидравлические и селективные свойства сорбентов. В результате исследования определены коэффициенты селективности, высота эквивалентной теоретической ступени для непрерывной и ступенчатой подачи ионита в колонну, получены параметрические модели, адекватно описывающее зависимость перепада давления через слой ионообменного материала и величины расширения ионообменного слоя от скорости потока и температуры.The object of the study are the characteristics of ion-exchange materials, which influence the processes of purification of process solutions from the diluted compounds. The aim of this work was to determine the impact of the selective properties of ion-exchange material, kinetic characteristics, and a method of implementing the process on the efficiency of the separation of ions of alkali and alkaline earth elements In the process of doing the work studied physico-chemical characteristics of ion-exchange material was determined in a kinetic, hydraulic and selective properties of the sorbents. The study identified the factors of selectivity, the height equivalent to theoretical stages for continuous and stepped feed of an ion exchanger in a column, adequately describing the dependence of the pressure drop through the layer of ion exchange material and the value of the expansion of the ion exchange layer from the flow rate and temperature

Comparing Probabilistic Models for Melodic Sequences

Modelling the real world complexity of music is a challenge for machine learning. We address the task of modeling melodic sequences from the same music genre. We perform a comparative analysis of two probabilistic models; a Dirichlet Variable Length Markov Model (Dirichlet-VMM) and a Time Convolutional Restricted Boltzmann Machine (TC-RBM). We show that the TC-RBM learns descriptive music features, such as underlying chords and typical melody transitions and dynamics. We assess the models for future prediction and compare their performance to a VMM, which is the current state of the art in melody generation. We show that both models perform significantly better than the VMM, with the Dirichlet-VMM marginally outperforming the TC-RBM. Finally, we evaluate the short order statistics of the models, using the Kullback-Leibler divergence between test sequences and model samples, and show that our proposed methods match the statistics of the music genre significantly better than the VMM.Comment: in Proceedings of the ECML-PKDD 2011. Lecture Notes in Computer Science, vol. 6913, pp. 289-304. Springer (2011

One- and two-photon resonant spectroscopy of hydrogen and anti-hydrogen atoms in external electric fields

The resonant spectra of hydrogen and anti-hydrogen atoms in the presence of an external electric field are compared theoretically. It is shown that nonresonant corrections to the transition frequency contain terms linear in the electric field. The existence of these terms does not violate space and time parity and leads to a difference in the resonant spectroscopic measurements for hydrogen and anti-hydrogen atoms in an external electric field. The one-photon 1s-2p and the two-photon 1s-2s resonances are investigated

Polarized point sources in the LOFAR Two-meter Sky Survey: A preliminary catalog

The polarization properties of radio sources at very low frequencies (h45m–15h30m right ascension, 45°–57° declination, 570 square degrees). We have produced a catalog of 92 polarized radio sources at 150 MHz at 4.′3 resolution and 1 mJy rms sensitivity, which is the largest catalog of polarized sources at such low frequencies. We estimate a lower limit to the polarized source surface density at 150 MHz, with our resolution and sensitivity, of 1 source per 6.2 square degrees. We find that our Faraday depth measurements are in agreement with previous measurements and have significantly smaller errors. Most of our sources show significant depolarization compared to 1.4 GHz, but there is a small population of sources with low depolarization indicating that their polarized emission is highly localized in Faraday depth. We predict that an extension of this work to the full LOTSS data would detect at least 3400 polarized sources using the same methods, and probably considerably more with improved data processing

Epigenetic and genetic variation at SKA2 predict suicidal behavior and post-traumatic stress disorder

Traumatic stress results in hypothalamic pituitary adrenal (HPA) axis abnormalities and an increased risk to both suicidal behaviors and post-traumatic stress disorder (PTSD). Previous work out of our laboratory identified SKA2 DNA methylation associations with suicidal behavior in the blood and brain of multiple cohorts. Interaction of SKA2 with stress predicted suicidal behavior with ~80% accuracy. SKA2 is hypothesized to reduce the ability to suppress cortisol following stress, which is of potentially high relevance in traumatized populations. Our objective was to investigate the interaction of SKA2 and trauma exposure on HPA axis function, suicide attempt and PTSD. SKA2 DNA methylation at Illumina HM450 probe cg13989295 was assessed for association with suicidal behavior and PTSD metrics in the context of Child Trauma Questionnaire (CTQ) scores in 421 blood and 61 saliva samples from the Grady Trauma Project (GTP) cohort. Dexamethasone suppression test (DST) data were evaluated for a subset of 209 GTP subjects. SKA2 methylation interacted with CTQ scores to predict lifetime suicide attempt in saliva and blood with areas under the receiver operator characteristic curve (AUCs) of 0.76 and 0.73 (95% confidence interval (CI): 0.6–0.92, P=0.003, and CI: 0.65–0.78, P<0.0001) and to mediate the suppression of cortisol following DST (β=0.5±0.19, F=1.51, degrees of freedom (df)=12/167, P=0.0096). Cumulatively, the data suggest that epigenetic variation at SKA2 mediates vulnerability to suicidal behaviors and PTSD through dysregulation of the HPA axis in response to stress

The multifaith campus: Transforming colleges and universities for spiritual engagement

Dafina Lazarus Stewart, Michael M. Kocet, and Sharon Lobdell explore what college and university campuses would look like if transformed to promote and sustain religious and secular pluralism and interfaith cooperation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/83741/1/20049_ftp.pd

A search for pulsations in the HgMn star HD 45975 with CoRoT photometry and ground-based spectroscopy

The existence of pulsations in HgMn stars is still being debated. To provide the first unambiguous observational detection of pulsations in this class of chemically peculiar objects, the bright star HD 45975 was monitored for nearly two months by the CoRoT satellite. Independent analyses of the light curve provides evidence of monoperiodic variations with a frequency of 0.7572 c/d and a peak-to-peak amplitude of ~2800 ppm. Multisite, ground-based spectroscopic observations overlapping the CoRoT observations show the star to be a long-period, single-lined binary. Furthermore, with the notable exception of mercury, they reveal the same periodicity as in photometry in the line moments of chemical species exhibiting strong overabundances (e.g., Mn and Y). In contrast, lines of other elements do not show significant variations. As found in other HgMn stars, the pattern of variability consists in an absorption bump moving redwards across the line profiles. We argue that the photometric and spectroscopic changes are more consistent with an interpretation in terms of rotational modulation of spots at the stellar surface. In this framework, the existence of pulsations producing photometric variations above the ~50 ppm level is unlikely in HD 45975. This provides strong constraints on the excitation/damping of pulsation modes in this HgMn star.Comment: Accepted for publication in A&A, 14 pages, 15 colour figures (revised version after language editing

Radiative Corrections to γγ→ttˉ\gamma\gamma\to t \bar t in the Electroweak Standard Model

The cross-section for $\gamma\gamma\to t \bar t$ with arbitrary polarized photons is calculated within the electroweak Standard Model including the complete virtual and soft-photonic $O(\alpha)$ corrections. We present a detailed numerical discussion of the radiative corrections with particular emphasis on the purely weak corrections. These are usually of the order of 1--10\% for energies up to 1 TeV. For unpolarized or equally polarized photons they reach almost 10\% close to threshold. The large corrections cannot be traced back to a universal origin like the running of $\alpha$ or the $\rho$-parameter. Apart from the energy region around the Higgs resonance $(\gamma\gamma\to H^*\to t\bar t)$ the weak corrections are widely independent of the Higgs-boson mass.Comment: 22 pages, LaTeX (compressed, uuencoded), 20 figures as compressed uuencoded ps-files, complete ps-file available via anonymous ftp from ftp://ftp.physik.uni-wuerzburg.de/pub/preprint/WUE-ITP-95-017.p

Observation of a Linearly Dispersing Collective Mode in a Quantum Hall Ferromagnet

Double layer two-dimensional electron systems can exhibit a fascinating collective phase believed to exhibit both quantum ferromagnetism and excitonic superfluidity. This unusual phase has recently been found to exhibit tunneling phenomena reminiscent of the Josephson effect. A key element of the theoretical understanding of this bizarre quantum fluid is the existence of linearly dispersing Goldstone collective modes. Using the method of tunneling spectroscopy, we have demonstrated the existence of these modes. We find the measured velocity to be in reasonable agreement with theoretical estimates.Comment: 5 pages, 4 figures; accepted for publication in PRL. Contains new data, a new figure, and a new titl