222 research outputs found
High resolution infrared absorption spectra, crystal field, and relaxation processes in CsCdBr_3:Pr^3+
High resolution low-temperature absorption spectra of 0.2% Pr^3+ doped
CsCdBr_3 were measured in the spectral region 2000--7000 cm-1. Positions and
widths of the crystal field levels within the 3H5, 3H4, 3F2, and 3F3 multiplets
of the Pr^3+ main center have been determined. Hyperfine structure of several
spectral lines has been found. Crystal field calculations were carried out in
the framework of the semiphenomenological exchange charge model (ECM).
Parameters of the ECM were determined by fitting to the measured total
splittings of the 3H4 and 3H6 multiplets and to the observed in this work
hyperfine splittings of the crystal field levels. One- and two-phonon
relaxation rates were calculated using the phonon Green's functions of the
perfect (CsCdBr_3) and locally perturbed (impurity dimer centers in
CsCdBr_3:Pr^3+) crystal lattice. Comparison with the measured linewidths
confirmed an essential redistribution of the phonon density of states in
CsCdBr_3 crystals doped with rare-earth ions.Comment: 16 pages, 5 tables, 3 figure
Structural and Optical Characterization of Luminescent (Y0.7Gd0.3)2O3:Eu3+Nanopowder and translucent Ceramics
Optical spectra, crystal-field parameters, and magnetic susceptibility of the new multiferroic NdFe3(BO3)4
We report high-resolution optical absorption spectra for NdFe3(BO3)4 trigonal
single crystal which is known to exhibit a giant magnetoelectric effect below
the temperature of magnetic ordering TN = 33 K. The analysis of the
temperature-dependent polarized spectra reveals the energies and, in some
cases, symmetries and exchange splittings of Nd3+ 84 Kramers doublets. We
perform crystal-field calculations starting from the exchange-charge model,
obtain a set of six real crystal-field parameters, and calculate wave functions
and magnetic g-factors. In particular, the values g(perpendicular) = 2.385,
g(parallel) = 1.376 were found for the Nd3+ ground-state doublet. We obtain
Bloc=7.88 T and |JFN|= 0.48 K for the values of the local effective magnetic
field at liquid helium temperatures at the Nd3+ site and the Nd - Fe exchange
integral, respectively, using the experimentally measured Nd3+ ground-state
splitting of 8.8 cm-1. To check reliability of our set of crystal field
parameters we model the magnetic susceptibility data from literature. A dimer
containing two nearest-neighbor iron ions in the spiral chain is considered to
partly account for quasi-one-dimensional properties of iron borates, and then
the mean-field approximation is used. The results of calculations with the
exchange parameters for Fe3+ ions Jnn = -6.25 K (intra-chain interactions) and
Jnnn = -1.92 K (inter-chain interactions) obtained from fitting agree well with
the experimental data.Comment: 13 pages, 8 figures, 2 table
Longitudinal Multimodal Transformer Integrating Imaging and Latent Clinical Signatures From Routine EHRs for Pulmonary Nodule Classification
The accuracy of predictive models for solitary pulmonary nodule (SPN)
diagnosis can be greatly increased by incorporating repeat imaging and medical
context, such as electronic health records (EHRs). However, clinically routine
modalities such as imaging and diagnostic codes can be asynchronous and
irregularly sampled over different time scales which are obstacles to
longitudinal multimodal learning. In this work, we propose a transformer-based
multimodal strategy to integrate repeat imaging with longitudinal clinical
signatures from routinely collected EHRs for SPN classification. We perform
unsupervised disentanglement of latent clinical signatures and leverage
time-distance scaled self-attention to jointly learn from clinical signatures
expressions and chest computed tomography (CT) scans. Our classifier is
pretrained on 2,668 scans from a public dataset and 1,149 subjects with
longitudinal chest CTs, billing codes, medications, and laboratory tests from
EHRs of our home institution. Evaluation on 227 subjects with challenging SPNs
revealed a significant AUC improvement over a longitudinal multimodal baseline
(0.824 vs 0.752 AUC), as well as improvements over a single cross-section
multimodal scenario (0.809 AUC) and a longitudinal imaging-only scenario (0.741
AUC). This work demonstrates significant advantages with a novel approach for
co-learning longitudinal imaging and non-imaging phenotypes with transformers
Quinones and non-quinones from the defensive secretion of unciger transsilvanicus (Verhoeff, 1899) (diplopoda, julida, julidae), from Serbia
A complex mixture of compounds was identified from the secretion of specimens of Unciger transsilvanicus. Phenol and p-cresol were detected for the first time in the family Julidae, and for the second time in the order Julida. Thirteen quinones were identified, with a great relative abundance of toloquinone and 2-methoxy-3-methyl- 1,4-benzoquinone. Hydroquinone was detected for the first time in the order Julida. Besides these compounds, isopentyl hexacosatetraenoate and isopentyl esters of saturated and unsaturated fatty acids with chain lengths from C-14 to C(20)were identified. The most abundant non-quinone compound was isopentyl eicosenoate. The relative abundance of quinone and non-quinone in the defensive fluid of U transsilvanicus was 77% and 23%, respectively. The phylogenetic importance of the registered compounds is briefly discussed
Multiclonal complexity of pediatric acute lymphoblastic leukemia and the prognostic relevance of subclonal mutations
Genomic studies of pediatric acute lymphoblastic leukemia (ALL) have shown remarkable heterogeneity in initial diagnosis, with multiple (sub)clones harboring lesions in relapse-associated genes. However, the clinical relevance of these subclonal alterations remains unclear. We assessed the clinical relevance and prognostic value of subclonal alterations in the relapse-associated genes IKZF1, CREBBP, KRAS, NRAS, PTPN11, TP53, NT5C2, and WHSC1 in 503 ALL cases. Using molecular inversion probe sequencing and breakpoint-spanning polymerase chain reaction analysis we reliably detected alterations with an allele frequency below 1%. We identified 660 genomic alterations in 285 diagnostic samples of which 495 (75%) were subclonal. RAS pathway mutations were common, particularly in minor subclones, and comparisons between RAS hotspot mutations revealed differences in their capacity to drive clonal expansion in ALL. We did not find an association of subclonal alterations with unfavorable outcome. Particularly for IKZF1, an established prognostic marker in ALL, all clonal but none of the subclonal alterations were preserved at relapse. We conclude that, for the genes tested, there is no basis to consider subclonal alterations detected at diagnosis for risk group stratification of ALL treatment.Development and application of statistical models for medical scientific researc
Guidance for the Management of Patients with Vascular Disease or Cardiovascular Risk Factors and COVID-19: Position Paper from VAS-European Independent Foundation in Angiology/Vascular Medicine .
COVID-19 is also manifested with hypercoagulability, pulmonary intravascular coagulation, microangiopathy, and venous thromboembolism (VTE) or arterial thrombosis. Predisposing risk factors to severe COVID-19 are male sex, underlying cardiovascular disease, or cardiovascular risk factors including noncontrolled diabetes mellitus or arterial hypertension, obesity, and advanced age. The VAS-European Independent Foundation in Angiology/Vascular Medicine draws attention to patients with vascular disease (VD) and presents an integral strategy for the management of patients with VD or cardiovascular risk factors (VD-CVR) and COVID-19. VAS recommends (1) a COVID-19-oriented primary health care network for patients with VD-CVR for identification of patients with VD-CVR in the community and patients' education for disease symptoms, use of eHealth technology, adherence to the antithrombotic and vascular regulating treatments, and (2) close medical follow-up for efficacious control of VD progression and prompt application of physical and social distancing measures in case of new epidemic waves. For patients with VD-CVR who receive home treatment for COVID-19, VAS recommends assessment for (1) disease worsening risk and prioritized hospitalization of those at high risk and (2) VTE risk assessment and thromboprophylaxis with rivaroxaban, betrixaban, or low-molecular-weight heparin (LMWH) for those at high risk. For hospitalized patients with VD-CVR and COVID-19, VAS recommends (1) routine thromboprophylaxis with weight-adjusted intermediate doses of LMWH (unless contraindication); (2) LMWH as the drug of choice over unfractionated heparin or direct oral anticoagulants for the treatment of VTE or hypercoagulability; (3) careful evaluation of the risk for disease worsening and prompt application of targeted antiviral or convalescence treatments; (4) monitoring of D-dimer for optimization of the antithrombotic treatment; and (5) evaluation of the risk of VTE before hospital discharge using the IMPROVE-D-dimer score and prolonged post-discharge thromboprophylaxis with rivaroxaban, betrixaban, or LMWH
Optimal treatment determination on the basis of haematoma volume and intra-cerebral haemorrhage score in patients with hypertensive putaminal haemorrhages: a retrospective analysis of 310 patients
COVID-19 infection in adult patients with hematological malignancies: a European Hematology Association Survey (EPICOVIDEHA)
Background: Patients with hematological malignancies (HM) are at high risk of mortality from SARS-CoV-2 disease 2019 (COVID-19). A better understanding of risk factors for adverse outcomes may improve clinical management in these patients. We therefore studied baseline characteristics of HM patients developing COVID-19 and analyzed predictors of mortality. Methods: The survey was supported by the Scientific Working Group Infection in Hematology of the European Hematology Association (EHA). Eligible for the analysis were adult patients with HM and laboratory-confirmed COVID-19 observed between March and December 2020. Results: The study sample includes 3801 cases, represented by lymphoproliferative (mainly non-Hodgkin lymphoma n = 1084, myeloma n = 684 and chronic lymphoid leukemia n = 474) and myeloproliferative malignancies (mainly acute myeloid leukemia n = 497 and myelodysplastic syndromes n = 279). Severe/critical COVID-19 was observed in 63.8% of patients (n = 2425). Overall, 2778 (73.1%) of the patients were hospitalized, 689 (18.1%) of whom were admitted to intensive care units (ICUs). Overall, 1185 patients (31.2%) died. The primary cause of death was COVID-19 in 688 patients (58.1%), HM in 173 patients (14.6%), and a combination of both COVID-19 and progressing HM in 155 patients (13.1%). Highest mortality was observed in acute myeloid leukemia (199/497, 40%) and myelodysplastic syndromes (118/279, 42.3%). The mortality rate significantly decreased between the first COVID-19 wave (March–May 2020) and the second wave (October–December 2020) (581/1427, 40.7% vs. 439/1773, 24.8%, p value < 0.0001). In the multivariable analysis, age, active malignancy, chronic cardiac disease, liver disease, renal impairment, smoking history, and ICU stay correlated with mortality. Acute myeloid leukemia was a higher mortality risk than lymphoproliferative diseases. Conclusions: This survey confirms that COVID-19 patients with HM are at high risk of lethal complications. However, improved COVID-19 prevention has reduced mortality despite an increase in the number of reported cases.EPICOVIDEHA has received funds from Optics COMMITTM (COVID-19 Unmet Medical Needs and Associated Research Extension) COVID-19 RFP program by GILEAD Science, United States (Project 2020-8223)
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