Analyzing How BERT Performs Entity Matching

State-of-the-art Entity Matching (EM) approaches rely on transformer architectures, such as BERT, for generating highly contextualized embeddings of terms. The embeddings are then used to predict whether pairs of entity descriptions refer to the same real-world entity. BERT-based EM models demonstrated to be effective, but act as black-boxes for the users, who have limited insight into the motivations behind their decisions. In this paper, we perform a multi-facet analysis of the components of pre-trained and fine-tuned BERT architectures applied to an EM task. The main findings resulting from our extensive experimental evaluation are (1) the fine-tuning process applied to the EM task mainly modifies the last layers of the BERT components, but in a different way on tokens belonging to descriptions of matching / non-matching entities; (2) the special structure of the EM datasets, where records are pairs of entity descriptions is recognized by BERT; (3) the pair-wise semantic similarity of tokens is not a key knowledge exploited by BERT-based EM models

Cephalopods caught in the outer Patagonian shelf and its upper and medium slope in relation to the main oceanographic features

Ninety cephalopod specimens were collected during the bottom trawl survey ATLANTIS 2009 undertaken between 24 February and 1 April 2009 The surveyed area was the zone between parallels 44◦and 48◦S, east of the Argentinean EEZ down to the 1500m depth on the HS of the SW Atlantic The collection was composed of 16 species of squids and 5 of octopods. The best represented groups were Histioteuthida (5 species) and Octopodidae(5). The most abundant species were Gonatusantarcticus(25.5%), Histioteuthisatlantica (11.1%), and Muusoctopuseureka (8.9%) The geographic and/or bathymetric distribution ranges of 9 species are extended, and this is the first record of Galiteuthis glacialis outside circumpolar Antarctic water

Dental radiology dosimetric data as routinely collected in an Italian hospital

The work presented here was developed in the framework of the SENTINEL Project and is devoted to the analysis of dental radiology dosimetric data. The procedure of data processing allows the analysis of some important aspects related to the protection of the patient and the staff because of the position of the operators near the patient and their exposure to the radiation scattered by the patient. Dental radiology data was collected in an Italian hospital. Following the Italian quality assurance (QA) protocols and suggestions by the leaders of the SENTINEL Project, X-ray equipment performances have been analysed in terms of: kVp accuracy, exposure time accuracy and precision, tube output, dose reproducibility and linearity, beam collimation, artefacts and light tightness. Referring to these parameters the physical quality index (QI) was analysed. In a single numerical value between 0 and 1, QI summarises the results of quality tests for radiological devices. The actual impact of such a figure (as suggested by international QA protocols or as adopted by local QA routine) on the policy of machine maintenance and replacement is discussed

Fast 3D-EM reconstruction using Planograms for stationary planar positron emission mammography camera

Summary At the University of Pisa we are building a PEM prototype, the YAP–PEM camera, consisting of two opposite 6×6×3 cm 3 detector heads of 30×30 YAP:Ce finger crystals, 2×2×30 mm 3 each. The camera will be equipped with breast compressors. The acquisition will be stationary. Compared with a whole body PET scanner, a planar Positron Emission Mammography (PEM) camera allows a better, easier and more flexible positioning around the breast in the vicinity of the tumor: this increases the sensitivity and solid angle coverage, and reduces cost. To avoid software rejection of data during the reconstruction, resulting in a reduced sensitivity, we adopted a 3D-EM reconstruction which uses all of the collected Lines Of Response (LORs). This skips the PSF distortion given by data rebinning procedures and/or Fourier methods. The traditional 3D-EM reconstruction requires several times the computation of the LOR-voxel correlation matrix, or probability matrix { p ij }; therefore is highly time-consuming . We use the sparse and symmetry properties of the matrix { p ij } to perform fast 3D-EM reconstruction. Geometrically, a 3D grid of cubic voxels (FOV) is crossed by several divergent 3D line sets (LORs). The symmetries occur when tracing different LORs produces the same p ij value. Parallel LORs of different sets cross the FOV in the same way, and the repetition of p ij values depends on the ratio between the tube and voxel sizes. By optimizing this ratio, the occurrence of symmetries is increased. We identify a nucleus of symmetry of LORs: for each set of symmetrical LORs we choose just one LOR to be put in the nucleus , while the others lie outside. All of the possible p ij values are obtainable by tracking only the LORs of this nucleus . The coordinates of the voxels of all of the other LORs are given by means of simple translation rules. Before making the reconstruction, we trace the LORs of the nucleus to find the intersecting voxels, whose p ij values are computed and stored with their voxel coordinates on a hard disk. Only the non-zero p ij are considered and their computation is performed just once. During the reconstruction, the stored values are loaded and are available in the random access memory for all of the operations of normalization, backprojection and projection: these are now performed rapidly, because the application of the translation rules is much faster than the probability computations. We tested the algorithm on Monte Carlo data fully simulating the typical YAP–PEM clinical condition. The adopted algorithm gives an excellent positioning capability for hot spots in the camera FOV. To use all of the possible skew LORs in the FOV avoids the software rejection of collected data. Reconstructed images indicate that a 5 mm diameter tumor of 37 kBq/cm 3 , in an active breast with a 10:1 Tissue to Background ratio (T/B), with a 10 min acquisition, for a head distance of 5 cm, can be detected by the YAP–PEM with a SNR of 8.7±1.0. The obtained SNR values depend linearly on the tumor volume. The algorithm allows one to discriminate between two hot sources of 5.0 mm diameter if they do not lie on the same axis. The YAP–PEM is now in the assembly stage

A MWPC with a cathode coupled delay line read-out as radioactivity detector for DNA repair studies

A non selective method for the isolation of DNA repair-deficient mutants in mammalian cells is discussed. The method requires radioactive labelling of the short DNA sequences synthesized during repair of damaged regions. Mutants should be recognized by the absence of radioactive incorporation into thier DNA. A multiwire proportional chamber (MWPC) is proposed as a suitable radioactivity detector. The performance of a MWPC prototype with a cathode coupled delay line read-out is described and is shown to be adequate for this application. The main avaantages of a MWPC are reviewed with respect to other methods used for β− radioactivity counting of biological samples, such as liquid scintillators or autoradiography: the proposed detection method is non destructive for the cells, which are being kept alive for further biological studies; furthermore many cell clones can be screened within a reasonable time

Radioiodide induces apoptosis in human thyroid tissue in culture.

Radioiodide (131I) is routinely used for the treatment of toxic adenoma, Graves' disease, and for ablation of thyroid remnant after thyroidectomy in patients with thyroid cancer. The toxic effects of ionizing radiations on living cells can be mediated by a necrotic and/or apoptotic process. The involvement of apoptosis in radiation-induced cell death in the thyrocytes has been questioned. The knowledge of the mechanisms that underlie the thyrocyte death in response to radiations can help to achieve a successful treatment with the lowest 131I dose. We developed a method to study the effects of 131I in human thyroid tissue in culture, by which we demonstrated that 131I induces thyroid cell apoptosis. Human thyroid tissues of about 1 mm3 were cultured in vitro and cell viability was determined up to 3 weeks by the MTT assay. Radioiodide added to the culture medium was actively taken up by the tissues. The occurrence of apoptosis in the thyrocytes was assessed by measuring the production of a caspase-cleavage fragment of cytokeratin 18 (M30) by an enzyme-linked immunoassay. Neither variation of cell number nor spontaneous apoptosis was revealed after 1 week of culture. 131I added to the culture medium induced a dose-dependent and a time-dependent generation of M30 fragment. The apoptotic process was confirmed by the generation of caspase-3 and PARP cleavage products. These results demonstrate that 131I induces apoptosis in human thyrocytes. Human thyroid tissue cultures may be useful to investigate the cell death pathways induced by 131I

Analysis of time-profiles with in-beam PET monitoring in charged particle therapy

Background: Treatment verification with PET imaging in charged particle therapy is conventionally done by comparing measurements of spatial distributions with Monte Carlo (MC) predictions. However, decay curves can provide additional independent information about the treatment and the irradiated tissue. Most studies performed so far focus on long time intervals. Here we investigate the reliability of MC predictions of space and time (decay rate) profiles shortly after irradiation, and we show how the decay rates can give an indication about the elements of which the phantom is made up. Methods and Materials: Various phantoms were irradiated in clinical and near-clinical conditions at the Cyclotron Centre of the Bronowice proton therapy centre. PET data were acquired with a planar 16x16 cm$^2$ PET system. MC simulations of particle interactions and photon propagation in the phantoms were performed using the FLUKA code. The analysis included a comparison between experimental data and MC simulations of space and time profiles, as well as a fitting procedure to obtain the various isotope contributions in the phantoms. Results and conclusions: There was a good agreement between data and MC predictions in 1-dimensional space and decay rate distributions. The fractions of $^{11}$C, $^{15}$O and $^{10}$C that were obtained by fitting the decay rates with multiple simple exponentials generally agreed well with the MC expectations. We found a small excess of $^{10}$C in data compared to what was predicted in MC, which was clear especially in the PE phantom.Comment: 9 pages, 5 figures, 1 table. Proceedings of the 20th International Workshop on Radiation Imaging Detectors (iWorid2018), 24-28 June 2018, Sundsvall, Swede

Novel high resolution detectors for Positron Emission Tomography (PET)

Abstract In this paper we present some recent results we have obtained in the development of detectors for small animal PET and for PEM, based on the use of Position Sensitive PMTS or Hybrid Photo Diodes (HPDs) coupled to crystal matrices. New ideas and future developments are discussed