Inductive algebras and homogeneous shifts

Inductive algebras for the irreducible unitary representations of the universal cover of the group of unimodular two by two matrices are classified. The classification of homogeneous shift operators is obtained as a direct consequence. This gives a new approach to the results of Bagchi and Misra

Superlinear Increase of Photocurrent due to Stimulated Scattering into a Polariton Condensate

We show that when a monopolar current is passed through an n-i-n structure, superlinear photocurrent response occurs when there is a polariton condensate. This is in sharp contrast to the previously observed behavior for a standard semiconductor laser. Theoretical modeling shows that this is due to a stimulated exciton-exciton scattering process in which one exciton relaxes into the condensate, while another one dissociates into an electron-hole pair.Comment: 17 pages with 10 figure

Method for Angiographically Guided Fine-Needle Diathermy in the Treatment of Corneal Neovascularization

Purpose: To describe a method to assess corneal neovascular (CoNV) complexes and identify feeder vessels for selective arterial fine-needle diathermy (FND). Methods: In patients with CoNV, color photography and corneal indocyanine green angiography (ICGA) and fluorescein angiography are performed. After injection of indocyanine green and sodium fluorescein dye, videography and single-frame images of the region of interest are recorded. Videography is used to measure the time to leakage to assess vessel maturity to guide medical treatment and to discern afferent from efferent vessels. Single-frame images are then selected to locate the number of afferent vessels for surgery, which are selectively cut with a 25-gauge marked needle for the application of FND. Results: Angiography using fluorescein and indocyanine green allows the characterization of CoNV based on assessment of both morphologic (ICGA) and functional (fluorescein angiography) parameters. The time to leakage of fluorescein dye provides important functional information on vessel maturity and helps discern whether medical treatment should be followed before surgical. ICGA allows the identification and delineation of afferent feeder vessels even in the presence of corneal opacities affecting biomicroscopic visibility. Colocalizing the afferent vessel to a visible venous landmark or branch is helpful for placement of the incision and application of FND. Using the described approach, angiographically identified feeder vessels can be selectively treated by FND with minimal thermal energy applied to the corneoscleral limbus. Conclusions: The described method for angiographically guided assessment of CoNV is a useful approach for guiding the medical and surgical treatment of CoNV

Genetic analysis of multiple synchronous lesions of the colon adenoma–carcinoma sequence

The colorectal adenoma–carcinoma sequence represents a well-known paradigm for the sequential development of cancer driven by the accumulation of genomic defects. Although the colorectal adenoma–carcinoma sequence is well investigated, studies about tumours of different dignity co-existent in the same patient are seldom. In order to address the distribution of genetic alterations in different lesions of the same patient, we coincidently investigated carcinomas, adenomas and aberrant crypt foci in patients with sporadic colon cancer. By utilizing polymerase chain reaction, single-strand conformation polymorphism, heteroduplex-analysis, restriction fragment length polymorphism, protein truncation test and sequencing techniques we looked for mutations and microsatellite instability of APC, H- ras, K- ras, p53, DCC and the DNA repair genes hMLH1/hMSH2. In accordance with the suggested adenoma–carcinoma sequence of the colon, four patients reflected the progressive accumulation of genetic defects in synchronously appearing tumours during carcinogenesis. However, two patients with non-hereditary malignomas presented different genetic instabilities in different but synchronously appearing tumours suggesting non-clonal growth under almost identical conditions of the environment. Thus, sporadically manifesting multiple lesions of the colon were not necessarily driven by similar genetic mechanisms. Premalignant lesions may transform into malignant tumours starting from different types of genetic instability, which indicates independent and simultaneous tumorigenesis within the same organ. © 2000 Cancer Research Campaig

The circulation and water masses in the Gulf of the Farallones

Six ADCP and CTD ship surveys of the continental shelf and slope in the vicinity of the Gulf of the Farallones, CA, were conducted in 1990}1992. ADCP data provide much more detail on the structure of the currents over the slope and shelf in the Gulf and reveal a persistent, largely barotropic poleward #ow with a complex mesoscale #ow "eld superimposed. The directly measured currents are not well represented by the geostrophic velocity "elds derived from hydrographic casts. Important upper-ocean circulation features include: a Slope Countercurrent (SCC), variable shelf circulation, and submesoscale eddy-like features. The SCC was present in all seasons and is believed due to a strong year-round positive wind-stress curl enhanced by Point Reyes. Its #ow was poleward throughout the upper 300 m, and often surface intensi"ed. Poleward transport in the upper 400 m was 1}3 Sv, much greater than previous geostrophic estimates for the California Current System constrained to a 500 dbar reference level. The shelf circulation was much more variable than the SCC and generally exhibited a pattern consistent with classic Ekman dynamics, responding to synoptic wind forcing. Submesoscale vortices, or eddies, often dominated the general #ow "eld. These eddies are thought to be generated by the frictional torque associated with current}topography interactions. Their centers typically have a distinct water type associated with either the SCC or the southward-#owing California Current. Higher spiciness anomalies, representing a higher percentage of Paci"c Equatorial Water (PEW), were typically found in the core of the SCC or within anticyclonic eddies. Lower (bland) spiciness anomalies, characteristic of a higher percentage of Paci"c Subarctic Water (PSAW), were associated with cyclonic eddies. While these circulation features were largely barotropic, the #ow also adjusted baroclinically to changes in the density "eld, as di!erent water types were advected by the general #ow "eld or by mesoscale instabilities in the large-scale boundary currents as they interacted with topography. Despite a seasonal cycle in regional wind and ocean temperature time series, there is no obvious seasonal pattern in the circulation. Most of the temporal variability in the current appears to be due to synoptic and interannual variations in atmospheric forcing. Because of the very dynamic three-dimensional nature of the regional circulation, the Gulf of the Farallones is likely to be a center for active mixing and exchange between the coastal and California Current waters, relative to most US west coast locales

Cross-Country Transportation Efficacy and Clinical Outcomes of Preloaded Large-Diameter Ultra-Thin Descemet Stripping Automated Endothelial Keratoplasty Grafts

PURPOSE: To evaluate the clinical outcomes of preloaded large-diameter ultra-thin grafts for Descemet stripping automated endothelial keratoplasty (UT-DSAEK) after cross-country shipment. METHODS: A laboratory study in an eye bank and a clinical cohort study in an academic tertiary care center were performed. UT-DSAEK (9.5 mm diameter) grafts (n = 7) were prepared, loaded into a commercial device (iGlide; Eurobio, Les Ulis, France), preserved for 4 days at room temperature in transport medium, and analyzed. In a retrospective study, preloaded tissues (n = 39) for clinical use were prepared, transported from Italy to the United Kingdom, and surgically delivered into the eyes of patients undergoing UT-DSAEK. Central and peripheral endothelial cell density (ECD) and viability were measured before and after loading and storage of the grafts in the laboratory study. Clinically, best-corrected visual acuity, ECD before and at final follow-up, dislocation rate, primary graft failure, and surgical time were recorded. RESULTS: In the laboratory study, postcut central graft thickness was 93.3 ± 17.2 μm. ECD and cell mortality did not change significantly before and after preservation (P = 0.8). Cell loss after 4 days of preservation was 1.7% ± 1.6%. Clinically, 39 eyes of 39 patients at final follow-up showed a mean central graft thickness of 88 ± 22 μm and a best-corrected visual acuity of 0.34 ± 0.24 logMAR. Nine of 39 cases (23%) needed rebubbling, and 28% cell loss was observed at final follow-up. CONCLUSIONS: Large-diameter UT-DSAEK grafts can be prepared and preloaded in the eye bank using the iGlide and transported to the surgical center facilitating surgery for patients undergoing UT-DSAEK, potentially reducing tissue wastage, surgical time, and costs related to surgery

Identification of Feeder Vessels in Ocular Surface Neoplasia using Indocyanine Green Angiography

Purpose: To evaluate indocyanine green angiography (ICGA) for the identification and characterization of afferent (feeding) and efferent (draining) vessels in patients with ocular surface neoplasia. Materials and Methods: Consecutive patients with biopsy-proven benign, pre-invasive, or invasive ocular surface tumors of the bulbar conjunctiva were included. Patients underwent anterior segment optical coherence tomography, ICGA, and color photography for the evaluation of the thickness, location, number, and diameter of afferent and efferent vessels of the lesions. Results: Twenty-two eyes of 22 patients with papillomas (n = 4), intra-epithelial neoplasia lesion (n = 2) in situ or invasive carcinomas (n = 6), nevus (n = 5), conjunctival melanocytic intra-epithelial neoplasia lesion (n = 1), and in situ or invasive melanomas (n = 4) were investigated. Afferent (feeder) vessels were identified in all lesions. There were fewer afferent (3.1 ± 1.6) than efferent (7.5 ± 3.5) vessels per lesion (p < 0.001) and the mean diameter was smaller for afferent (101 ± 62 μm, 28–281) than efferent vessels (137 ± 51 μm, 31–652; p = 0.017). The number of afferent and efferent vessels was associated with the thickness of the lesion (p = 0.037, p < 0.01). Lesion filling times differed between benign and invasive or pre-invasive lesions (p = 0.018). Conclusions: ICGA is a useful adjunctive in vivo imaging method for the assessment of the vasculature in patients with suspected ocular surface neoplasia

Top Radiative Corrections in Non-minimal Standard Models

We derive the one-loop effective action induced by a heavy top in models with an extended Higgs sector. We use the effective action to analyze the top corrections to the $\rho$ parameter and to the Higgs-gauge boson couplings. We show that in models with $\rho\not=1$ at tree-level, one does not lose generally the bound on $m_t$ from the $\rho$ parameter.Comment: 9 pages, phyzzx file, UPR-0603T. (a new reference has been added