Search

We compute the one-loop divergences in a theory of gravity with Lagrangian of the general form $f(R,R_{����}R^{����})$, on an Einstein background. We also establish that the one-loop effective action is invariant under a duality that consists of changing certain parameters in the relation between the metric and the quantum fluctuation field. Finally, we discuss the unimodular version of such a theory and establish its equivalence at one-loop order with the general case., 14 pages, v2:minor corrections, refs. added/modified

We compute the one-loop effective action in unimodular gravity, starting from two different classical formulations of the theory. We find that the effective action is the same in both cases, and agrees with the one of General Relativity.

Tumor size is important when distinguishing T1 renal cell carcinoma (RCC) from T2 disease. However, further details of the relationship between tumor size and TNM classifications have not been reported. In this study, we evaluated the correlation between the size and TNM stage of RCC and compared it with correlations for tumor volume. We retrospectively studied 241 patients with RCC and obtained data on size and TNM stage from surgical records. To assess the correlation of these variables with involvement of the renal capsule, lymph node metastasis, and distant metastasis, the area under the corresponding receiver-operator characteristic (ROC) curve was calculated. The statistical significance of differences between these ROC curves was also studied. With respect to involvement of the renal capsule, the areas under the ROC curves for tumor size and volume were 0.796 and 0.800, respectively. There was no significant difference between tumor size and tumor volume. With lymph node metastasis, the areas for tumor size and volume were 0.751 and 0.757, respectively. With distant metastasis they were 0.693 and 0.722, respectively. The areas for tumor volume were larger than those for tumor size, but there were no significant differences between these 2 variables. By using a cutoff value of 5 cm for tumor size and 65 mL for tumor volume, we obtained a high sensitivity and specificity in detecting renal capsular invasion. Tumor size and volume are both sensitive and specific indices of renal capsular invasion. These variables, obtained before surgery by imaging modalities, could be useful for preoperative staging of RCC, especially for T staging.

Optical conductivity s(w) of PrRu4P12 has been studied under high pressure to 14 GPa, at low temperatures to 8 K, and at photon energies 12 meV-1.1 eV. The energy gap in s(w) at ambient pressure, caused by a metal-insulator transition due to an unconventional charge-density-wave formation at 63 K, is gradually filled in with increasing pressure to 10 GPa. At 14 GPa and below 30 K, s(w) exhibits a pronounced Drude-type component due to free carriers. This indicates that the initial insulating ground state at zero pressure has been turned into a metallic one at 14 GPa. This is consistent with a previous resistivity study under pressure, where the resistivity rapidly decreased with cooling below 30 K at 14 GPa. The evolution of electronic structure with pressure is discussed in terms of the hybridization between the 4f and conduction electrons., Comment: 7 pages, 6 figures

Mathematical models of memory are useful for describing basic processes of memory in a way that enables generalization across a number of experimental paradigms. Models that have these characteristics do not just engage in empirical curve-fitting, but may also provide explanations for puzzling phenomena and may lead to new discoveries. This chapter provides a number of examples, taken from previous research with the SAM model. Although previous research has focused exclusively on the explanation of episodic memory, recent research within the SAM/REM approach has extended this model to implicit and semantic memory phenomena. This review provides some speculations on how this approach may be extended to deal with a number of basic data in implicit memory. It is emphasized that constructing a model for implicit memory necessitates the development of detailed models of lexical-semantic processing.

Item does not contain fulltext

The nonlinear optical properties of one-dimensional all-solid-state photonic-crystal microcavities (MCs) are ex-perimentally studied by second- harmonic generation (SHG) spectroscopy in both the frequency and the wave- vector domains. The studied single and coupled MCs are formed by the alternating of mesoporous silicon layers of different porosities. When the fundamental radiation is in resonance with the MC mode the second-harmonic intensity is enhanced by a factor of approximately 10 2 . The resonant SHG response is compared with the off-resonance response, as the fundamental wavelength is outside the photonic bandgap. The split-ting of the modes of two identical coupled MCs is observed in the wave-vector domain spectrum of enhanced SHG. The SHG enhancement is attributed to the combined effects of the spatial localization of the funda-mental field in the MC spacer and the fulfillment of the phase-matching conditions. The confinement of the resonant fundamental field is probed directly at the MC cleavage by a scanning near-field optical microscope. The role of the phase matching that is associated with the giant effective dispersion in the spectral vicinity of the MC mode is deduced from a comparison with the SHG peaks at both edges of the photonic bandgap.

We tested 2 prototypes of an operating fiberoptic nephroureteroscope, measuring 3.5 and 4.5mm. in diameter, that have an adequate working channel for auxiliary instruments and irrigation. Difficulty in passing the fiberscope through the ureteral orifice was overcome by dilation with balloon and polytetrafluoroethylene (Teflon) dilators. Our initial trial for stone retrieval under fiberscopic control was performed on 21 patients with upper ureteral and renal calculi. A stone was removed successfully in 15 of the 21 patients (71 per cent). After electrohydraulic lithotripsy calculi were extracted successfully in 9 of 11 patients (82 per cent). Three patients suffered ureteral perforation. The fiberscope was especially helpful when an upper ureteral stone moved back to the kidney during stone manipulation.

The synthesis and biological evaluation of [2-Valine-A] insulin ([Val2-A]insulin) is reported. In this insulin, the isoleucine residue in position A2, invariant in the majority of mammalian insulins, is substituted by valine. The same substitution, along with four others, occurs naturally in the insulin produced by the owl monkey. Owl monkey insulin exhibits ca. 20% of the activity of porcine insulin in in vitro insulin assays using human cells in culture. [Val2-A]insulin displays 20-22% of the activity of bovine insulin in in vitro insulin assays using rat liver plasma membranes or isolated rat adipocytes. We suggest that the substitution of valine for isoleucine at position A2 is responsible for all or most of the diminution in potency of owl monkey insulin relative to porcine insulin. The data are discussed with regard to previous findings with insulin analogues in which isoleucine A2 was replaced with norleucine, glycine and alanine.