Search

Both imaging and intervention play an increasingly important role in the management of renal masses in general and renal cancer in particular. Indeed, radiologists are often the first to detect and diagnose renal cancer, and now with the burgeoning role of percutaneous ablation, they are often the treating physicians. Renal mass management begins with imaging, and although most can be diagnosed with a high degree of certainty using imaging, some remain indeterminate and require biopsy or observation, now referred to as active surveillance. Although active surveillance strategies have been employed for indeterminate renal masses that have a reasonable chance of being benign, recent data suggest that some renal cancers can undergo active surveillance safely. This article reviews the current imaging-based diagnostic evaluation of incidentally detected small renal masses, the burgeoning role of percutaneous biopsy, and how both imaging and biopsy are used to help select which patients need treatment and which can undergo active surveillance. [ABSTRACT FROM AUTHOR]

Niobium materials with intermediate purity level are used for fabrication of superconducting radio frequency cavities (SCRF), and thermal conductivity is an important parameter influencing the performance of such SCRF cavities. We report here the temperature and magnetic field dependence of thermal conductivity k for superconducting niobium (Nb) samples, for which the electron mean free path le, the phonon mean free path lg, and the vortex core diameter 2rC are of the same order of magnitude. The measured thermal conductivity is analyzed using the effective gap model (developed for le » 2rC (Dubeck et al 1963 Phys. Rev. Lett. 10 98)) and the normal core model (developed for le » 2rC (Ward and Dew-Hughes 1970 J. Phys. C: Solid St. Phys. 3 2245)). However, it is found that the effective gap model is not suitable for low temperatures when le ∼ 2rC. The normal core model, on the other hand, is able to describe k(T,H) over the entire temperature range except in the field regime between HC1 and HC2 i.e. in the mixed state. It is shown that to understand the complete behavior of k in the mixed state, the scattering of quasi-particles from the vortex cores and the intervortex quasi-particle tunneling are to be invoked. The quasi-particle scattering from vortices for the present system is understood in terms of the framework of Sergeenkov and Ausloos (1995 Phys. Rev. B 52 3614) extending their approach to the case of Nb. The intervortex tunneling is understood within the framework of Schmidbauer et al (1970 Z. Phys. 240 30). Analysis of the field dependence of thermal conductivity shows that while the quasi-particle scattering from vortices dominates in the low fields, the intervortex quasi-particle tunneling dominates in high fields. Analysis of the temperature dependence of thermal conductivity shows that while the quasi-particle scattering is dominant at low temperatures, the intervortex quasi-particle tunneling is dominant at high temperatures. [ABSTRACT FROM AUTHOR]

Purpose: To determine the utility of 3.0-Tesla diffusion-weighted (DW) magnetic resonance imaging (MRI) for focal cystic pancreatic lesion (FCPL) characterization. Materials and methods: 55 FCPL (34 IPMN, 5 serous cystadenoma, and 16 inflammatory) were evaluated. Two radiologists reviewed in consensus DW-MRI images. Reference standard was obtained from patient history, cytological and histopathology data, FCPL fluid analysis, and follow-up imaging results. Signal intensity (SI) and apparent diffusion coefficient values (ADC) of FCPL and normal pancreas were measured. FCPL-to-pancreas SI and ADC ratios were also calculated. Results: Qualitatively, 11 of 21 non-mucinous vs. 4 of 34 mucinous lesions appeared hyperintense at b value of 1,000 s/mm ( P = 0.02). Three FCPL demonstrated restricted diffusion: all inflammatory. Significant differences in mean ADC between neoplastic vs. non-neoplastic ( P = 0.009), and mucinous vs. non-mucinous ( P = 0.013) lesions were demonstrated. FCPL-to-pancreas ADC and SI ratios demonstrated significant differences between neoplastic vs. non-neoplastic lesions [ADC, ( P = 0.019); SI for b values 750 ( P = 0.010) and 1,000 s/mm ( P = 0.017)] and mucinous vs. non-mucinous lesions [ADC ( P = 0.018); SI for b values 750 ( P = 0.013) and 1,000 s/mm ( P = 0.015)]. Conclusion: Although mean ADC values and FCPL-to-pancreas SI and ADC ratios may be helpful in differentiating FCPL, characterization of individual FCPL by means of 3.0-Tesla DW-MRI appears limited. [ABSTRACT FROM AUTHOR]

Purpose: Evaluate the utility of multidetector-row computed tomography (MDCT) in assessing the severity of ulcerative colitis (UC) in comparison with clinical assessment, colonoscopy, and histopathology. Materials and methods: Patients with UC evaluated with at least one abdominal contrast-enhanced CT study (CECT) within 7 days of colonoscopy with biopsy were included. CECT of 23 patients (12 male; mean age 40 years; age range, 20-72 years) were retrospectively evaluated in consensus by two radiologists. A total of 138 lower GI tract segments were evaluated by CECT and graded for the presence of bowel wall thickening, mucosal hyperenhancement, mural stratification, mesenteric hyperemia, pericolonic stranding, and lymph nodes. A cumulative CT severity score was calculated and correlated with clinical, colonoscopic, and histopathologic severity grades. Results: The cumulative CT score and individual CECT scores for bowel wall thickening, mucosal hyperenhancement, and mural stratification showed positive correlation with clinical severity ( P < 0.05). All individual CECT features as well as the cumulative CT score demonstrated statistically significant correlation with colonoscopic severity ( P < 0.0001). Only wall thickening on CECT demonstrated significant correlation with histopathologic severity ( P = 0.01). Conclusion: Disease severity assessment by MDCT demonstrates positive correlation with severity established by clinical assessment and colonoscopy. Only increasing wall thickness, as graded on MDCT, correlates with histopathologic disease severity. [ABSTRACT FROM AUTHOR]

Background: To describe the CT and MRI features of autoimmune hepatitis (AIH) and correlate them with histological grade and stage. Observed changes associated with treatment are also described. Methods: A retrospective analysis of the initial CT scans (n = 22) and MRI exams (n = 12) of 27 patients with pathologically-proven AIH was conducted. Multiple objective and subjective imaging features were evaluated. Correlation of imaging features with histological inflammatory grade and fibrotic stage was performed using the Fisher exact test and Spearman's rank correlation coefficient. In eight patients serial CT and MR imaging during treatment was used to describe the changes associated with treatment. Results: The presence of ascites, expanded gallbladder fossa, spleen size, and enlarged preportal space had significant positive correlations with fibrotic stage. No significant positive correlations existed between imaging features and portal or lobular inflammatory grade. Seven patients (25.9%) were normal. The most common abnormal finding was surface nodularity: CT (n = 11 [50%]) and MRI (n = 8 [66.7%]). There was a wide variability in imaging appearances of patients who had serial scans on treatment. Conclusions: There is a wide spectrum of CT and MR imaging features in patients with AIH. Several MRI features demonstrate a significant positive correlation with fibrotic stage. [ABSTRACT FROM AUTHOR]

At BARC, development of a Low Energy High Intensity Proton Accelerator (LEHIPA), as front-end injector of the 1 GeV accelerator for the ADS programme, has been initiated. The major components of LEHIPA (20 MeV, 30 mA) are a 50 keV ECR ion source, a 3 MeV Radio Frequency Quadrupole (RFQ) and a 20 MeV drift tube linac (DTL). The Low Energy Beam Transport (LEBT) and Medium Energy Beam Transport (MEBT) lines match the beam from the ion source to RFQ and from RFQ to DTL respectively. Design of these systems has been completed and fabrication of their prototypes has started. Physics studies of the 20-1000 MeV part of the Linac are also in progress. In this paper, the present status of this project is presented. [ABSTRACT FROM AUTHOR]

In a recent paper we proposed the expansion of the space of variations in energy calculations by considering the approximate wave function, ψ, to be a functional of functions χ : ψ&ThickSpace;=&ThickSpace;ψ [χ], rather than a function. The space of variations is expanded because such a functional can in principle be adjusted through the function χ to reproduce the true wave function. For the determination of an approximate wave function functional, a constrained search is first performed over the subspace of all functions χ such that ψ [χ] satisfies a physical constraint or leads to the known value of an observable. A rigorous upper bound to the energy is then obtained by application of the variational principle. To demonstrate the advantages of the expansion of variational space, we apply the constrained search–variational method to the ground state of the negative ion of atomic hydrogen, the helium atom, and its isoelectronic sequence. The method is equally applicable to excited states, and its extension to such states in conjunction with the theorem of Theophilou is described. We also briefly describe our approach to the many-electron problem. [ABSTRACT FROM AUTHOR]

The human immunodeficiency virus (HIV) pandemic is nearly 20 years old. HIV infection is characterized by profound immunodeficiency resulting in an increased incidence of opportunistic infections and neoplasms. However, the greatest paradox is the occurrence of certain autoimmune disorders in the setting of HIV. These include diffuse interstitial lymphocytosis syndrome (DILS), reactive arthritis, systemic lupus erythematosus (SLE), and rheumatoid arthritis (RA). It has also been seen that even in the absence of these well-defined diseases, various rheumatological manifestations such as arthralgias, arthritis, myopathy, vasculitis, and sicca syndrome are commonly associated with HIV. To the best of our knowledge, the association of HIV with scleroderma has not previously been reported. [ABSTRACT FROM AUTHOR]

The temperature and field dependences of in-plane (IP) and out-of-plane (OP) anisotropic magnetoresistances (AMRs) have been measured in La 1 - x Pb x MnO 3 (LPMO) thin films having different microstructures, namely the single-crystal (SC), nanocrystalline (NC) and polycrystalline (PC) microstructures. The OP AMR, irrespective of the microstructure, is found to be considerably larger than the IP AMR. The magnetization data show that the larger OP AMR arises because magnetization is favoured in the film plane owing to strain anisotropy. In addition, the temperature and field dependences of both IP and OP AMRs are governed by the crystallinity of the films, indicating that the AMRs are strongly influenced by the magnetization process. [ABSTRACT FROM AUTHOR]

We introduce a new cosmological diagnostic pair {r,s} called the Statefinder. The Statefinder is a geometrical diagnostic and allows us to characterize the properties of dark energy in a model-independent manner. The Statefinder is dimensionless and is constructed from the scale factor of the Universe and its time derivatives only. The parameter r forms the next step in the hierarchy of geometrical cosmological parameters after the Hubble parameter H and the deceleration parameter q, while a is a linear combination of q and r chosen in such a way that it does not depend upon the dark energy density. The Statefinder pair {r,s} is algebraically related to the equation of state of dark energy and its first time derivative. The Statefinder pair is calculated for a number of existing models of dark energy having both constant and variable w. For the case of a cosmological constant, the Statefinder acquires a particularly simple form. We demonstrate that the Statefinder diagnostic can effectively differentiate between different forms of dark energy. We also show that the mean Statefinder pair can be determined to very high accuracy from a SNAP-type experiment. © 2003 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]