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J A Aramburu

Publications and source records attributed to J A Aramburu.

4 recordsLinked to original sources
PubMed2004

Impurities in noncubic crystals: stabilization mechanisms for Jahn-Teller ions in layered perovskites.

Mechanisms responsible for the local geometry around Jahn-Teller impurities in K2NiF4 type lattices are shown to be different from those generating the warping in cubic crystals. The present density functional theory calculations reveal that the elastic anisotropy of the host lattice (visible for closed shell impurities) and the electric field created by the rest of lattice ions upon active electrons make it possible to have d(9) ions in an elongated geometry but with a A(1g) ground state. The puzzling difference between equilibrium geometries for Cu2+ and Ni+ in layered perovskites can reasonably be understood.

Journal Article↗
PubMed2001

Fine-needle aspiration biopsy of liver masses: diagnostic value and reproducibility of cytological criteria.

There are many helpful cytological criteria for the diagnosis of liver fine-needle aspiration biopsies (FNABs), but none of them are pathognomonic of primary or metastatic tumors. We analyzed the diagnostic value and reproducibility of 28 cytological parameters in FNABs from 140 hepatic masses, including 29 benign lesions, 49 hepatocellular carcinomas (HCCs), and 62 metastatic tumors, encompassing 48 adenocarcinomas (ACAs). Five different observers evaluated each sample, and the interobserver and intraobserver agreement was studied. Multivariable analysis showed that the criteria more closely associated with malignancy were irregular nuclear contour, three-dimensional cell groups, and atypical naked nuclei. Capillaries separating tumor cells and granular cytoplasm were strongly associated with HCCs, while eccentrically placed nuclei and necrosis were most commonly seen in ACAs and in metastatic tumors. The intraobserver and interobserver agreement was excellent for the final cytological diagnosis, and there was fair to very good interobserver agreement for 22 of the 28 criteria studied. Architectural features were less reproducible than pure cytological criteria. Intraobserver variability was not influenced by the years of experience in the field. A precise and strict definition of terminology rendered a better reproducibility of the cytological criteria.

Biopsy, Needle↗
PubMed1997

Extensively calcified synovial sarcoma.

Synovial sarcoma is an uncommon fibroblastic soft tissue neoplasm, commonly arising near, but not necessarily from, the synovium of joint capsules, bursae or tendon sheaths. The radiological diagnosis is difficult. We present a case of synovial sarcoma studied with plain film radiography, CT, and pathology that had an unusual extensive calcification, which complicated its radiological diagnosis.

Adult↗