167 research outputs found

    Machine learning approach to pattern recognition in nuclear dynamics from the ab initio symmetry-adapted no-core shell model

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    A novel machine learning approach is used to provide further insight into atomic nuclei and to detect orderly patterns amidst a vast data of large-scale calculations. The method utilizes a neural network that is trained on ab initio results from the symmetry-adapted no-core shell model (SA-NCSM) for light nuclei. We show that the SA-NCSM, which expands ab initio applications up to medium-mass nuclei by using dominant symmetries of nuclear dynamics, can reach heavier nuclei when coupled with the machine learning approach. In particular, we find that a neural network trained on probability amplitudes for ss-and pp-shell nuclear wave functions not only predicts dominant configurations for heavier nuclei but in addition, when tested for the 20^{20}Ne ground state, it accurately reproduces the probability distribution. The nonnegligible configurations predicted by the network provide an important input to the SA-NCSM for reducing ultra-large model spaces to manageable sizes that can be, in turn, utilized in SA-NCSM calculations to obtain accurate observables. The neural network is capable of describing nuclear deformation and is used to track the shape evolution along the 2042^{20-42}Mg isotopic chain, suggesting a shape-coexistence that is more pronounced toward the very neutron-rich isotopes. We provide first descriptions of the structure and deformation of 24^{24}Si and 40^{40}Mg of interest to x-ray burst nucleosynthesis, and even of the extremely heavy nuclei such as 166,168^{166,168}Er and 236^{236}U, that build upon first principles considerations.Comment: 10 pages, 9 figure

    Investigate the Possibility of Using Phosphorescence in Clinical Oncology as an Early Prognostic Test in Detecting Brain Carcinogenesis.

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    Phosphorescence is considered one of the non-invasive glioblastoma testing methods based on studying molecular energy and the metabolism of L-tryptophan (Trp) through KP, which provides essential information on regulating immunity and neuronal function. This study aimed to conduct a feasibility study using phosphorescence in clinical oncology as an early prognostic test in detecting Glioblastoma. This study was conducted on 1039 patients who were operated on with follow-up between January 1, 2014, and December 1, 2022, and retrospectively evaluated in participating institutions in Ukraine (the Department of Oncology, Radiation Therapy, Oncosurgery, and Palliative Care at the Kharkiv National Medical University). Method of protein phosphorescence detection included two steps. During the first step, of luminol-dependent phosphorescence intensity in serum was carried out after its activation by the light source, according to the spectrofluorimeter method, as follows. At a temperature of 30 °C, serum drops were dried for 20 min to form a solid film. After that, we put the quartz plate with dried serum in a phosphoroscope of luminescent complex and measured the intensity. With the help of Max-Flux Diffraction Optic Parallel Beam Graded Multilayer Monochromator (Rigaku Americas Corporation) following spectral lines as 297, 313, 334, 365, 404, and 434 nm were distinguished and absorbed by serum film in the form of light quantum. The monochromator exit split width was 0.5 mm. Considering the limitations of each of the non-invasive tools currently available, phosphorescence-based diagnostic methods are ideally integrated into the NIGT platform: a non-invasive approach for visualizing a tumor and its main tumor characteristics in the spatial and temporal order. Because trp is present in virtually every cell in the body, these fluorescent and phosphorescent fingerprints can be used to detect cancer in many different organs. Using phosphorescence, it is possible to create predictive models for GBM in both primary and secondary diagnostics. This will assist clinicians in selecting the appropriate treatment option, monitoring treatment, and adapting to the era of patient-centered precision medicine

    Collaborative Online Learning: Plurilingual and Pluricultural Development

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    Background. The growing importance of international cooperation among universities have increased the number of joint training projects. Common Bologna principles followed by Russian and Spanish tertiary institutions helped perform a pilot study focused on telecollaboration and plurilingual and pluricultural competence implementation. The project aimed at forming plurilingual and pluricultural competence and communicative competence among students studying either English or Spanish or both through the integration of digital technologies into the learning process.Methods. This 7-month study took place in Moscow (Russian Federation) and Valencia (Spain) from November 2019 to June 2020. Participants were university students aged 20–23 from Teaching Training Faculties from Lomonosov Moscow State University and CEU Cardenal Herrera University. The undergraduates who volunteered to participate in the focus group took part in five telecollaboration sessions (March-May 2020). The participants were divided into two mixed (50% Russian and 50% Spanish learners) subgroups and discussed suggested topics during online studentled bilingual sessions. After each online interaction, researchers collected their opinions through questionnaires and discussion with a lecturer.Outcomes. All participants announced that the study gave them a chance to improve their language abilities, update their vocabulary and enhance their intercultural experience. None of the partakers reported having experienced any difficulty doing the project and only regretted that interaction time was too short. Additionally, lecturers were able to test new curricula implementation and assessment procedures.Conclusions. The pilot study was feasible to deliver and there was a clear, satisfactory result with the focus groups participants and teaching staff

    CASSIS: The Cornell Atlas of Spitzer/Infrared Spectrograph Sources. II. High-resolution observations

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    The Infrared Spectrograph (IRS) on board the Spitzer Space Telescope observed about 15,000 objects during the cryogenic mission lifetime. Observations provided low-resolution (R~60-127) spectra over ~5-38um and high-resolution (R~600) spectra over ~10-37um. The Cornell Atlas of Spitzer/IRS Sources (CASSIS) was created to provide publishable quality spectra to the community. Low-resolution spectra have been available in CASSIS since 2011, and we present here the addition of the high-resolution spectra. The high-resolution observations represent approximately one third of all staring observations performed with the IRS instrument. While low-resolution observations are adapted to faint objects and/or broad spectral features (e.g., dust continuum, molecular bands), high-resolution observations allow more accurate measurements of narrow features (e.g., ionic emission lines) as well as a better sampling of the spectral profile of various features. Given the narrow aperture of the two high-resolution modules, cosmic ray hits and spurious features usually plague the spectra. Our pipeline is designed to minimize these effects through various improvements. A super sampled point-spread function was created in order to enable the optimal extraction in addition to the full aperture extraction. The pipeline selects the best extraction method based on the spatial extent of the object. For unresolved sources, the optimal extraction provides a significant improvement in signal-to-noise ratio over a full aperture extraction. We have developed several techniques for optimal extraction, including a differential method that eliminates low-level rogue pixels (even when no dedicated background observation was performed). The updated CASSIS repository now includes all the spectra ever taken by the IRS, with the exception of mapping observations

    Spitzer observations of Abell 1763 - II: Constraining the nature of activity in the cluster-feeding filament with VLA and XMM-Newton data

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    The Abell 1763 superstructure at z=0.23 contains the first galaxy filament to be directly detected using mid-infrared observations. Our previous work has shown that the frequency of starbursting galaxies, as characterized by 24{\mu}m emission is much higher within the filament than at either the center of the rich galaxy cluster, or the field surrounding the system. New VLA and XMM-Newton data are presented here. We use the radio and X-ray data to examine the fraction and location of active galaxies, both active galactic nuclei (AGN) and starbursts. The radio far-infrared correlation, X-ray point source location, IRAC colors, and quasar positions are all used to gain an understanding of the presence of dominant AGN. We find very few MIPS-selected galaxies that are clearly dominated by AGN activity. Most radio selected members within the filament are starbursts. Within the supercluster, 3 of 8 spectroscopic members detected both in the radio and in the mid-infrared are radio-bright AGN. They are found at or near the core of Abell 1763. The five starbursts are located further along the filament. We calculate the physical properties of the known wide angle tail (WAT) source which is the brightest cluster galaxy (BCG) of Abell 1763. A second double lobe source is found along the filament well outside of the virial radius of either cluster. The velocity offset of the WAT from the X-ray centroid, and the bend of the WAT in the intracluster medium (ICM) are both consistent with ram pressure stripping, indicative of streaming motions along the direction of the filament. We consider this as further evidence of the cluster-feeding nature of the galaxy filament.Comment: 26 pages, 13 figures AJ, accepte

    Forbush decrease observed by SEVAN particle detector network on November 4, 2021

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    On November 3-4 2021, an interplanetary coronal mass injection (ICME) hits the magnetosphere, sparking a strong G3-class geomagnetic storm and auroras as far south as California and New Mexico. All detectors of the SEVAN network registered a Forbush decrease (FD) of 5-10 percentdeep in 1 minute time series of count rates. We present the results of a comparison of Fd registered on mountain altitudes on Aragats (Armenia), Lomnicky Stit (Slovakia), Musala (Bulgaria), and at sea level DESY (Hamburg, Germany), and in Mileshovka, Czechia. We present as well purity and barometric coefficients of different coincidences of SEVAN detector layers on Aragats. We demonstrate disturbances of the near-surface electric (NSEF) and geomagnetic fields at the arrival of the ICME on Earth

    Correlation Effects in Nuclear Transparency

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    The Glauber approximation is used to calculate the contribution of nucleon correlations in high-energy A(e,eN)A(e,e'N) reactions. When the excitation energy of the residual nucleus is small, the increase of the nuclear transparency due to correlations between the struck nucleon and the other nucleons is mostly compensated by a decrease of the transparency due to the correlations between non detected nucleons. We derive Glauber model predictions for nuclear transparency for the differential cross section when nuclear shell level excitations are measured. The role of correlations in color transparency is briefly discussed.Comment: 24 pages revtex, 4 uuencoded PostScript Figures as separate fil

    ФАЗОВЫЕ ПРЕВРАЩЕНИЯ ПРИРОДНЫХ ЦЕОЛИТОВ ПРИ КИСЛОТНОЙ И ЩЕЛОЧНОЙ ОБРАБОТКАХ

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    The change of zeolite properties of the ‘Noyemberyanskoe’ deposit (Armenia) after their processing with alkaline and acidic solutions (1­6 mol/dm3 ) has been studied by X­ray diffraction and dip pycnometry. It has been established that chemical composition and specific total pore volume of clinoptilolite were changed, and also new phases, such as sodalite, gismondine and fillipsite, were formed at sodium hydroxide concentration of ≥ 2 mol/dm3 . It has been found that increasing the hydrochloric acid concentration up to ≈ 6 mol/dm3 leads to size and form change of clinoptilolite sorption channels, and further increase causes its destruction. The method of low­temperature nitrogen adsorption­desorption proved the presence of mesoporous constituent in a clinoptilolite rock.Методами дифракции рентгеновских лучей и жидкостной пикнометрии изучено изменение свойств цеолитов Ноемберянского месторождения (Армения) после их обработки щелочными и кислотными растворами (1–6 моль/л). Установлено, что при концентрациях натрия гидроксида ≥ 2 моль/л изменяются химический состав и удельный сум­марный объем пор клиноптилолита, а также образуются новые фазы, такие как содалит, жисмондин и филлипсит. Выявлено, что увеличение концентрации соляной кислоты до ≈ 6 моль/л приводит к изменению размеров и форм сорбционных каналов клиноптилолита, а свыше этих значений – к его разрушению. Методом низкотемпературной адсорбции–десорбции азота доказано наличие мезопористой составляющей в образцах клиноптилолитовой породы

    Identifying Luminous AGN in Deep Surveys: Revised IRAC Selection Criteria

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    Spitzer IRAC selection is a powerful tool for identifying luminous AGN. For deep IRAC data, however, the AGN selection wedges currently in use are heavily contaminated by star-forming galaxies, especially at high redshift. Using the large samples of luminous AGN and high-redshift star-forming galaxies in COSMOS, we redefine the AGN selection criteria for use in deep IRAC surveys. The new IRAC criteria are designed to be both highly complete and reliable, and incorporate the best aspects of the current AGN selection wedges and of infrared power-law selection while excluding high redshift star-forming galaxies selected via the BzK, DRG, LBG, and SMG criteria. At QSO-luminosities of log L(2-10 keV) (ergs/s) > 44, the new IRAC criteria recover 75% of the hard X-ray and IRAC-detected XMM-COSMOS sample, yet only 38% of the IRAC AGN candidates have X-ray counterparts, a fraction that rises to 52% in regions with Chandra exposures of 50-160 ks. X-ray stacking of the individually X-ray non-detected AGN candidates leads to a hard X-ray signal indicative of heavily obscured to mildly Compton-thick obscuration (log N_H (cm^-2) = 23.5 +/- 0.4). While IRAC selection recovers a substantial fraction of luminous unobscured and obscured AGN, it is incomplete to low-luminosity and host-dominated AGN.Comment: 22 pages, 15 figures, accepted for publication in ApJ, full resolution version available at http://www.stsci.edu/~donley/iragn_paper

    PERMANENT MAGNET QUADRUPOLE FOR THE 1-ST TANK OF LINAC-4 *

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    Abstract A rare-earth (REPM) ∅60 mm diameter, 45 mm long quadrupole for the LINAC-4 focusing channel with an integrated gradient of 2.3 T is described. Thin side washers are used for tuning the quad into specified gradient integral with ±0.5 % accuracy. The single washer contribution calculations are discussed. A method for limiting to 30 μm the magnetic axis offset in the REPM quad is discussed to exclude its compensation by the outer diameter machining before inserting into the drift tube. Nonlinearity of the field is less than 1 % in the reference range of 75 % of beam aperture at the central crosssection near the quad axis. The angular quadrupole arrangement in the drift tube will be provided by machining the main groove on the quad surface in the median plane with 1 mrad accuracy. Calculations of the longitudinal gradient distribution between two neighbour quadrupoles showed that some percents should be added to the nominal gradient in the beginning of the LINAC-4 focusing channel because of partial field compensation
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