Quasi-2D Fermi surface in the anomalous superconductor UTe2.

The heavy fermion paramagnet UTe2 exhibits numerous characteristics of spin-triplet superconductivity. Efforts to understand the microscopic details of this exotic superconductivity have been impeded by uncertainty regarding the underlying electronic structure. Here we directly probe the Fermi surface of UTe2 by measuring magnetic quantum oscillations in pristine quality crystals. We find an angular profile of quantum oscillatory frequency and amplitude that is characteristic of a quasi-2D Fermi surface, which we find is well described by two cylindrical Fermi sheets of electron- and hole-type respectively. Additionally, we find that both cylindrical Fermi sheets possess considerable undulation but negligible small-scale corrugation, which may allow for their near-nesting and therefore promote magnetic fluctuations that enhance the triplet pairing mechanism. Importantly, we find no evidence for the presence of any 3D Fermi surface sections. Our results place strong constraints on the possible symmetry of the superconducting order parameter in UTe2.

Longitudinal Spin Fluctuations Driving Field-Reinforced Superconductivity in UTe_{2}.

Our measurements of ^{125}Te NMR relaxations reveal an enhancement of electronic spin fluctuations above µ_{0}H^{*}∼15 T, leading to their divergence in the vicinity of the metamagnetic transition at µ_{0}H_{m}≈35 T, below which field-reinforced superconductivity appears when a magnetic field (H) is applied along the crystallographic b axis. The NMR data evidence that these fluctuations are dominantly longitudinal, providing a key to understanding the peculiar superconducting phase diagram in H∥b, where such fluctuations enhance the pairing interactions.

Field Induced Multiple Superconducting Phases in UTe_{2} along Hard Magnetic Axis.

The superconducting (SC) phase diagram in uranium ditelluride is explored under magnetic fields (H) along the hard magnetic b axis using a high-quality single crystal with T_{c}=2.1 K. Simultaneous electrical resistivity and ac magnetic susceptibility measurements discern low- and high-field SC (LFSC and HFSC, respectively) phases with contrasting field-angular dependence. Crystal quality increases the upper critical field of the LFSC phase, but the H^{*} of ∼15 T, at which the HFSC phase appears, is always the same through the various crystals. A phase boundary signature is also observed inside the LFSC phase near H^{*}, indicating an intermediate SC phase characterized by small flux pinning forces.

Effect of uranium deficiency on normal and superconducting properties in unconventional superconductor UTe2.

Single crystals of the unconventional superconductor UTe2have been grown in various conditions which result in different superconducting transition temperature as well as normal state properties. Stoichiometry of the samples has been characterized by the single-crystal x-ray crystallography and electron microprobe analyses. Superconducting samples are nearly stoichiometric within an experimental error of about 1%, while non-superconducting sample significantly deviates from the ideal composition. The superconducting UTe2showed that the large density of states was partially gapped in the normal state, while the non-superconducting sample is characterized by the relatively large electronic specific heat as reported previously.

[CT colonography - evolution of methodology and indications]. / CT kolonografie - prehled vývoje metodiky a indikací

BACKGROUND: Advances in CT scanners technology and computing in 90s allowed visual reconstruction of hollow organs inner surface. This method which was mainly used for colon wall imaging had to deal with several limitations from the very first years caused by poorly developed methodology of colonic preparation and distension as well as high radiation exposure. DESIGN: Aim of the paper is to provide an overview of technical and methodological innovations that can at least partially overcome above mentioned shortcomings. Due to these changes, CT colonography became the recognized method after incomplete or impossible optical colonography. Specific patient subgroups which particularly benefit from this modality and unresolved role of the CT colonography in colorectal cancer screening are also mentioned. CONCLUSION: CT colonography is a relatively new method that can not completely replace optical colonoscopy. Thanks to advances in technology, however, it became a valid diagnostic tool with certain advantages over other imaging or invasive methods. These benefits can be handed over to a patient when the examination is carefully indicated.

[Li-Fraumeni syndrome - a proposal of complex prevention care for carriers of TP53 mutation with total-body MRI]. / Li-Fraumeni syndrom - návrh komplexní preventivní péce o nosice TP53 mutace s pouzitím celotelové magnetické rezonance.

Li-Fraumeni syndrome (LFS) is one of the most serious hereditary cancer syndromes with high risk of malignancy already in childhood. Adrenocortical carcinoma, brain tumor, leukemia, sarcoma are the most frequent malignancies in children. Early breast cancer, brain tumor, sarcoma, skin cancer, gastrointestinal, lung, gynecological, hematological and other malignancies can be seen in adults. Predictive testing in families with detected LFS and TP53 mutation is offered from the age of 18 for various reasons. One of the most important reasons is a very limited effectivity of prevention especially in children, also the possible risk of psychological harm to the child and his family caused by the diagnosis of this syndrome. Progress in diagnostic methods, especially total body MRI, enables to propose preventive care for early cancer diagnoses for children and adults. Biochemical tests, ultrasound, MRI may improve survival of these high risk individuals and support the possibility of predictive testing in children.

[The role of PET in the diagnosis and prediction of the treatment response in patients with cervical carcinoma treated with radiotherapy--results of pilot study]. / Význam PET v diagnostice a predikci lécebné odpovedi karcinomu cervixu u pacientek lécených radioterapií--výsledky pilotní studie.

BACKGROUND: Positron emission tomography (PET) is used to distinguish between benign and malign tumours, to diagnose relapse or post-therapeutic changes and recentlyto predict treatment response. PET is also a complementary method to determine target volumes in radiotherapy. Using the PET in routine oncology practice can change disease management and improve treatment outcomes of cancer patients. We performed a pilot study to validate the role of PET in staging and in radiotherapy treatment planning of cervical carcinoma. PATIENTS AND METHODS: Between March 2005 and May 2007, 51 patients with cervical carcinoma were treated with combination of external beam radiotherapy and HDR brachytherapy, with or without concomitant cisplatin. The lymphatic nodes treatment field size was determined by PET/CT fusion. Treatment results were evaluated by PET 3 and 9 months after completion of radiotherapy. RESULTS: The difference in the results of PET and CT was evaluated in this study. In 32 cases (62.75%) the results of initial PET and CT were identical, in 14 cases (27.45%) the nodal involvement was more extensive according to PET, in 5 cases (9.8%) the nodal involvement was more extensive according to CT. Comparing the results of PET done before and 3 months after the treatment, we found stable disease in 3 cases (5.88%), progression of disease in 4 cases (7.84%), partial regression in 3 cases (5.88 %) and in 35 cases (68.63 %) both PET scans were negative. There should not occur any false positive results caused by inflammatory reaction persisting 3 months after radiotherapy, as was confirmed by repeating PET 9 months after the treatment. CONCLUSION: The results of this study confirmed the important role of PET in diagnosis and treatment of cervical carcinoma and for determination of target volumes in radiotherapy. The predictive value of PET has not yet been validated in our study. PET was integrated into the standard staging of cervical carcinoma in Masaryk Memorial Cancer Institute.

[Attempt at restoring the health of pigs suffering from atrophic rhinitis]. / Pokus o ozdravení chovu prasat s výskytem sípavky.

A group of 24 sows selected from herds affected by atrophic rhinitis was subjected to the study of the therapeutic effect of the administration of wide-spectrum antibiotics combined with an improvement of the zoohygienic conditions and with full-value nutrition in the pre-partal period and during lactation. It was found that the mentioned measures in sows before parturition and their housing in a sanitized farrowing house during treatment generally improved the health of the sows and enabled the rearing of healthy piglets. The mortality rate during rearing up to the age of 28 days was 12.5%. In the control group of piglets and sows the losses amounted to 29%; the clinical symptoms of rhinitis were found in 11% of the piglets already at the age of 28 days.