A spatial light phase modulator with an effective resolution of 4 mega-pixels

We report the design, construction and characterization of a 4 mega-pixel, optically-addressed, spatial light modulator (OSLM). The intensity distribution corresponding to a kinoform is displayed across two wide-screen liquid crystal on silicon displays, the images of which are combined and relayed to the address face of a 40 mm aperture OSLM. This spatially varying intensity profile is converted into a phase hologram on the readout side of the OSLM. When illuminated at 532 nm we measure a first-order diffraction efficiency of ≈50% at 400 line pairs and ≈20% at 900 line pairs. We show that aberration associated with the non-flatness of the device can be corrected within software by modification of the hologram.     

On the focussing of light,as limited by the uncertainty principle

Equations indicating the minimum size of the focal spot in an optical system appear in various forms. Many of these are approximations to special cases, such as the size of the Airy ring pattern produced by a circular lens as a function of its aperture size, wavenumber, k ₀, and focal length, f. Various forms of focal point engineering enable arbitrarily narrow central maxima. However, a simple application of the uncertainty principle suggests an underlying limit to the spread of the intensity distribution in the focal plane that cannot be bettered. For cylindrically symmetric focussing elements and intensity distributions, the root mean square radius, r _rms, in the lens plane is related to that in the focal plane, R _rms, by r _rms R _rms ≥ f/k ₀.     

Optical tweezers and optical spanners with Laguerre–Gaussian modes

Abstract

We numerically model the axial trapping forces within optical tweezers arising from Laguerre–Gaussian laser modes. For an 8 μm diameter sphere suspended in water, the higher-order modes produce an axial trapping force several times larger than that of the fundamental. Partial absorption results in a transfer of the orbital angular momentum from the Laguerre–Gaussian mode to the trapped particle. This results in the rotation of the particle by what may be called an optical spanner (wrench). For an absorption coefficient of α = 5700 m^?1 and a laser power of 10 mW, we find that an 8 μm diameter sphere would acquire an angular acceleration of 10 × 10⁴ rad s^?2 and a limiting angular velocity of 0.2 rad s^?1.     

The role of coronary angiography and coronary revascularization before noncardiac vascular surgery

OBJECTIVE: To determine whether preoperative coronary angiography and revascularization improve short-term outcomes in patients undergoing noncardiac vascular surgery. DESIGN: Decision analysis. PATIENTS: Patients undergoing elective vascular surgery who had either no angina or mild angina and a positive dipyridamole-thallium scan result. INTERVENTIONS: Three strategies were compared. The first strategy was to proceed directly to vascular surgery. The second was to perform coronary angiography, followed by selective coronary revascularization, before proceeding to vascular surgery and to cancel vascular surgery in patients with severe inoperable coronary artery disease (CAD). The third was to perform coronary angiography, followed by selective coronary revascularization, before proceeding to vascular surgery and to perform vascular surgery in patients with inoperable CAD. MAIN OUTCOME MEASURES: Mortality, nonfatal myocardial infarction, stroke, uncorrected vascular disease, and cost. All outcomes were assessed within 3 months. RESULTS: Proceeding directly to vascular surgery led to lower morbidity and cost in the base case analysis. The coronary angiography strategy led to higher mortality if vascular surgery would proceed in patients with inoperable CAD, but led to slightly lower mortality if vascular surgery were canceled in patients with inoperable CAD. The coronary angiography strategy also led to lower mortality when vascular surgery was particularly risky. CONCLUSIONS: Decision analysis indicates vascular surgery without preoperative coronary angiography generally leads to better outcomes. Preoperative coronary angiography should be reserved for patients whose estimated mortality from vascular surgery is substantially higher than average.     

N-acetylglucosaminyltransferase regulates the expression of neolactoglycolipids including sulfoglucuronylglycolipids in the developing nervous system

Lactosylceramide N-acetylglucosaminyltransferase (GlcNac-Tr) in the synthesis of lactotriosylceramide (LcOse3Cer) was characterized in the nervous system. The microsomal membrane GlcNAc-Tr required a divalent metal ion, preferably Mn2+, and a nonionic detergent. The pH optimum was around 7.0. The enzyme also transferred GlcNAc to neolactotetraosylceramide (nLcOse4Cer), GM1, and asialo-GM1, but not to other glycolipids. The Km value for lactosylceramide was 21 microM (Vmax = 91 pmol/mg/h), and that for nLcOse4Cer was 35 microM (Vmax = 112 pmol/mg/h). The GlcNAc-Tr for the glycolipids appears to be separate from that for oligosaccharides. The developmental expression of GlcNAc-Tr, both in the cerebral cortex and cerebellum, correlated well with the tissue levels of LcOse3Cer, nLcOse4Cer, sulfoglucuronylglycolipids (SGGLs), and other neolacto series glycolipids (nLSGs). In the cerebral cortex, the specific activity of GlcNAc-Tr decreased sharply from a maximum level at embryonic day 15, and by postnatal day 10 onward, it was undetectable. In the adult cerebral cortex, although significant activities of other glycosyltransferases involved in the subsequent steps of the synthesis of SGGLs were present, the absence of GlcNAc-Tr stymied the formation of LcOse3Cer and therefore the synthesis of nLSGs, including SGGLs. In the cerebellum, the GlcNAc-Tr specific activity declined from the day of birth to postnatal day 3, but later, the activity increased and reached a maximum at postnatal day 15, which correlated with the increasing synthesis of nLSGs. The results indicate that lactosylceramide GlcNAc-Tr is the key regulatory enzyme controlling the differential expression of all nLSGs in the developing nervous system.     

Cyclosporin greatly improves the quality of life of adults with severe atopic dermatitis. A randomized, double-blind, placebo-controlled trial

A multicentre, randomized, double-blind, controlled crossover clinical trial was conducted on 33 patients with severe refractory atopic dermatitis, to determine the effects of cyclosporin (5 mg/kg/day) on their health-related quality of life. Treatments were administered for 8-week periods. One group (n = 16) received placebo followed by cyclosporin, and the other (n = 17) received cyclosporin and then placebo. Health-related quality of life was assessed at 0, 8 and 16 weeks using a general measure, the United Kingdom Sickness Impact Profile (UKSIP), an eczema-specific measure, the Eczema Disability Index (EDI), and a global 5-point rating scale of overall health (very good to very poor). In addition, clinical assessments (i.e. extent and activity of disease) were made by the investigators. UKSIP and EDI scores indicated significant improvement in quality of life (P < 0.05-P < 0.01) of patients with atopic dermatitis after treatment with cyclosporin. Although no patient required withdrawal from the study, 20 patients receiving cyclosporin reported adverse events, compared with eight taking placebo. There was a close correlation (P < 0.05-P < 0.01) between the UKSIP and EDI scores. In contrast, there was either no correlation, or only a very poor correlation, between the quality of life parameters and clinical measures of extent and activity of eczema. When cyclosporin was stopped, relapse was rapid, but the mean scores for disease activity and extent of disease were less than their baseline values (i.e. an improvement of greater than 25% was maintained in 11 patients at week 4).(ABSTRACT TRUNCATED AT 250 WORDS)     

Mode selection in doubly-resonant optical parametric oscillators

By using a computer model to calculate the threshold for each signal and idler mode-pair in doubly resonant optical parametric oscillators, we investigate the effects of the three principal tuning parameters (temperature, cavity length, and pump wavelength) on the mode selection. Through consideration of type I and type II noncritical phase-matched geometries for lithium triborate optical parametric oscillators, we illustrate that the tuning behavior depends on the difference between the refractive indexes experienced by the signal and idler fields     

Flexible endoscopes in treatment of colloid cysts of the third ventricle

Today's most important problems in diagnosing renal cell carcinoma are the methods for early detection and correct evaluation of disease stage. For early diagnosis, the abdominal ultrasonic diagnostic method should be used to screen the kidney in regional health checkups and complete medical examinations. In order to improve the accuracy of stage evaluation, various imaging modalities currently available should be used comprehensively. Chest radiography and abdominal CT scanning are especially effective. In detecting metastatic lesions, we should pay special attention to the fact that renal cell carcinomas tend to metastasize to the lung, liver and bone. At present, renal cell carcinoma is diagnosed principally by imaging, also in early diagnosis. It is desirable to establish tumor markers in the near future.