National Ignition Facility system alignment.

The National Ignition Facility (NIF) is the world's largest optical instrument, comprising 192 37 cm square beams, each generating up to 9.6 kJ of 351 nm laser light in a 20 ns beam precisely tailored in time and spectrum. The Facility houses a massive (10 m diameter) target chamber within which the beams converge onto an ∼1 cm size target for the purpose of creating the conditions needed for deuterium/tritium nuclear fusion in a laboratory setting. A formidable challenge was building NIF to the precise requirements for beam propagation, commissioning the beam lines, and engineering systems to reliably and safely align 192 beams within the confines of a multihour shot cycle. Designing the facility to minimize drift and vibration, placing the optical components in their design locations, commissioning beam alignment, and performing precise system alignment are the key alignment accomplishments over the decade of work described herein. The design and positioning phases placed more than 3000 large (2.5 m×2 m×1 m) line-replaceable optics assemblies to within ±1 mm of design requirement. The commissioning and alignment phases validated clear apertures (no clipping) for all beam lines, and demonstrated automated laser alignment within 10 min and alignment to target chamber center within 44 min. Pointing validation system shots to flat gold-plated x-ray emitting targets showed NIF met its design requirement of ±50 µm rms beam pointing to target chamber. Finally, this paper describes the major alignment challenges faced by the NIF Project from inception to present, and how these challenges were met and solved by the NIF design and commissioning teams.

Influence of back mixing on the convective drying of residual sludges in a fixed bed.

The influence of a backmixing operation on the convective belt drying of two wastewater sludges was studied. The expansion of the sludge extrudates bed due to increasing additions of dry product was quantified by using X-ray tomography. This non-invasive technique was used to determine the bed porosity and the total exchange area available for heat and mass transfers, for increasing levels of backmixing. For a same drying flux, the expansion of the drying bed leads to higher drying rates, allowing a reduction of the total drying time. In this context, rheological properties of the sludges are key properties.

Wastewater sludge convective drying: influence of sludge origin.

This paper deals with thermal drying of wastewater sludges, whose management will become crucial in the forthcoming years. Sludges collected after mechanical dewatering in 5 different WWTPs are submitted to the same convective drying treatment in order to try finding some relations between the drying behaviours, the type of effluent and wastewater treatments. Results show dearly sludge drying remains a particularly complex operation because sludges may exhibit very different behaviours, both from kinetic and texture points of view. Initial moisture content and global composition are not sufficient to explain the different observed behaviours. It is too early to claim one or another type of water treatment has an influence on the drying behaviour. However, the drying rates can be classified in the inverse order of the organic content. Moreover for sludges at the same siccities, the harder the material (rheological properties), the higher the drying rate. Final textural properties can be related to the rheological properties and the internal diffusion limitations lowering the drying intensity.

Rapid dynamics of the microtubule binding of ensconsin in vivo.

Microtubule-associated proteins (MAPs) are proteins that reversibly bind to and regulate microtubule dynamics and functions in vivo. We examined the dynamics of binding of a MAP called ensconsin (E-MAP-115) to microtubules in vivo. We used 5xGFP-EMTB, a construct in which the microtubule-binding domain of ensconsin (EMTB) is fused to five copies of green fluorescent protein (GFP), as a reporter molecule amenable to the use of fluorescent speckle microscopy. Fluorescent speckle microscopy (FSM) sequences and kymograph analyses showed rapid dynamics of speckles comprised of 5xGFP-EMTB in untreated cells. By contrast, in detergent-lysed cytoskeletons, speckles were not dynamic. Since detergent-lysed cytoskeletons differ from living cells in that they lack both ATP and dynamic microtubules, we used azide treatment to substantially reduce the level of ATP in living cells and we used Taxol to halt microtubule dynamics. Both treatments slowed the dynamics of 5xGFP-EMTB speckles observed by FSM. We also used fluorescence recovery after photobleaching (FRAP) to quantify the half-time of binding and dissociation of the 5xGFP-EMTB chimera and to compare this half-time to that of the full-length MAP molecule. In untreated cells, the t(g) of either 5xGFP-EMTB or full-length GFP-ensconsin was similarly rapid (approximately 4 seconds), while in ATP-reduced and Taxol-treated cells, t(g) was increased to 210 seconds and 40 seconds, respectively. In detergent-extracted cells no recovery was seen. Consistent with the rapid dynamics of 5xGFP-EMTB measured with fluorescent speckle microscopy and FRAP, we estimated that the affinity of the MAP for microtubules is approximately 40 microM in untreated living cells, compared with approximately 1 microM in vitro. However, K(D,app) was not significantly changed in the presence of azide and was increased to 110 microM in the presence of Taxol. To test whether changes in the phosphorylation state of cellular proteins might be responsible for altering the dynamics of ensconsin binding, we used FSM to monitor staurosporine-treated cells. Staurosporine treatment substantially halted dynamics of 5xGFP-EMTB speckles along MTs. Our results show that ensconsin is highly dynamic in its association with microtubules, and its microtubule association can be altered by in vivo phosphorylation events.

Quantitative shedding of two genotypes of Cryptosporidium parvum in California ground squirrels (Spermophilus beecheyi).

Sixteen percent of California ground squirrels (Spermophilus beecheyi) were found to be shedding an average of 53,875 Cryptosporidium parvum oocysts/g of feces. Male squirrels had a higher prevalence and higher intensity of shedding than did female squirrels. The majority of C. parvum isolates matched a bovine-murine genotype, with a few isolates resembling a porcine genotype. Higher intensities of shedding by males may enhance dissemination and genotypic mixing of this protozoa given males' proclivity to disperse to nonnatal colonies.

Reference axis selection: subcommittee report of the OSA Working Group to establish standards for measurement and reporting of optical aberrations of the eye.

It is the committee's recommendation that the ophthalmic community use the line of sight as the reference axis for the purposes of calculating and measuring the ocular optical aberrations.

Myopia progression in adolescent wearers of soft contact lenses and spectacles.

The purpose of this 3-year, randomized clinical trial was to determine the difference in myopia progression in adolescents wearing soft contact lenses over a control group wearing spectacles. A total of 175 adolescents between the ages of 11 and 14 years were randomized into 2 groups, spectacle wearers and soft contact lens wearers. The main result was that the spherical equivalent change between the groups showed no clinical or statistically significant difference. However, when a power vector analysis was used, which uses all the refractive error data, a small but statistically significant (F test = 4.24, T2 = 17.35, p < 0.01) difference between the groups was found (i.e., the refractive error of the spectacle wearers had a slight increase in astigmatism). It can be concluded that soft contact lens wear does not lead to additional myopia progression in adolescents.

Comparison of the eye's wave-front aberration measured psychophysically and with the Shack-Hartmann wave-front sensor.

The Shack-Hartmann wave-front sensor offers many theoretical advantages over other methods for measuring aberrations of the eye; therefore it is essential that its accuracy be thoroughly tested. We assessed the accuracy of a Shack-Hartmann sensor by directly comparing its measured wave-front aberration function with that obtained by the Smirnov psychophysical method for the same eyes. Wave-front profiles measured by the two methods agreed closely in terms of shape and magnitude with rms differences of approximately lambda/2 and approximately lambda/6 (5.6-mm pupil) for two eyes. Primary spherical aberration was dominant in these profiles, and, in one subject, secondary coma was opposite in sign to primary coma, thereby canceling its effect. Discovery of an unusual, subtle wave-front anomaly in one individual further demonstrated the accuracy and sensitivity of the Shack-Hartmann wave-front sensor for measuring the optical quality of the human eye.

Concentrations of heroin, 06-monoacetylmorphine, and morphine in a lethal case following an oral heroin overdose.

A case of lethal overdose by heroin ingestion is presented. The concentrations of drugs were measured several hours after death. Heroin, 06-monoacetylmorphine, and morphine were identified and quantitated in blood, urine, and gastrointestinal contents by gas chromatography-mass spectrometry and high-performance liquid chromatography. Concentrations of heroin, 06-monoacetylmorphine, and morphine were 109, 168, and 1140 ng/mL, respectively, in blood and 17, 12, and 425 ng/g, respectively, in gastrointestinal content. In urine, however, only morphine was detected at 3650 ng/mL.

Subjective refraction of the peripheral field using contrast detection acuity.

BACKGROUND: Although peripheral resolution acuity is relatively unaffected by uncorrected refractive error, recent investigations of peripheral vision indicate that contrast detection is optically limited. It should be possible, therefore, to perform a subjective refraction in the peripheral visual field using a contrast detection task. METHODS: For a range of trial lenses, contrast detection acuities for vertical and horizontal gratings were measured with a two-interval forced-choice paradigm. Lens powers that maximized detection acuity were taken as the subjective refraction estimates. These powers were compared with objective refractions determined with retinoscopy and autorefractometry. RESULTS: Contrast detection acuity varied significantly with lens power at all retinal locations tested. Defocusing by one diopter from the optimum lens power reduced detection acuity by about a factor of two at 20 degrees eccentricity, and slightly less in the far periphery. Objective retinoscopy and autorefractometry agreed with subjective measurements for most conditions tested. CONCLUSIONS: Contrast detection acuity in the peripheral visual field varies with refractive blur, demonstrating the feasibility of performing subjective refraction in the periphery for a contrast detection task. Results suggest that visual fields measured with standard perimetry, which is based on contrast detection, may be affected by uncorrected peripheral refractive errors.

A new subjective refraction method--the meridional polarized vernier optometer.

BACKGROUND: The purpose of this study was to develop a more accurate and precise method for measuring subjective sphero-cylindrical refractive errors. It employed the principles of a vernier optometer and meridional refraction. METHODS: A meridional polarized vernier optometer was used to measure the refraction of three subjects. Trial lenses were added to change the refractive error by known amounts and refractions were repeated to assess accuracy. RESULTS: Refractions were within the range expected. The instrument had a slight bias (+0.04D) and 95 percent confidence interval of +/- 0.45D for measuring change in refractive error. Mean standard deviation for repeated measurements was 0.08D. CONCLUSIONS: This new approach has the potential to measure subjective refractive errors more accurately than is possible with current methods.

Comparison of elevation, curvature, and power descriptors for corneal topographic mapping.

Corneal topography systems sample thousands of surface points and from these data different descriptors are derived to create maps of the cornea. Without visualizing and comparing the maps, it is difficult to appreciate the implications of each descriptor for mapping. We created and compared several maps of an ellipsotoric cornea based on the following surface descriptors: relative elevation, dioptric curvature, and refractive power. Each map presented a different picture of the same cornea. Only elevation maps show true topography but must be calculated relative to an appropriate reference surface to reveal important features. Axial and to a greater degree instantaneous curvature maps bring out optically significant shape asymmetries but misrepresent refractive power away from the apex. Ray tracing maps display optical properties that are not apparent from the elevation or curvature maps, including spherical aberration. Oblique astigmatism can be described using a pair of maps for the sagittal and tangential powers at each surface point. A knowledge of these principles is necessary to interpret color maps of the corneal surface correctly.

Development and testing of a synchronous-scanning underwater imaging system capable of rapid two-dimensional frame imaging.

The design and construction of a synchronous-scanning underwater imaging system capable of rapid two-dimensional scanning are described. The imager employs a 7-W, all-lines, argon-ion laser in onjunction with a galvanometrically driven raster scanner and an image-dissector tube receiver. The imager is capable of directly generating real-time RS-170 video imagery. The results of an in-water test of the imaging system, in which a high-contrast imaging test pattern was imaged, demonstrate operating anges of up to 4 attenuation lengths (AL) when the test was run at real-time frame rates, ranges of 5.1-5.5 AL when the system operated with an eight-frame running average, and ranges of 6.3 AL when a 128-frame running average was used. The system performance was compared with that of several floodlight/silicon-intensified-target TV camera configurations, which produced a maximum imaging range of ∼2.6 AL. Also, an imaging configuration that used the raster-scanned beam of the laser as an illumination source for the sil n-intensified-target camera was tested. That system had an ultimate range of ∼ 4 AL.

Rural high school students' knowledge, attitudes and behaviours related to sexually transmitted diseases.

High school students are at high risk for contracting sexually transmitted diseases (STDs). A sample of 69 rural high school students from the province of Alberta, Canada were surveyed regarding their knowledge, attitudes and behaviours related to STDs to ascertain whether they differ from urban students. Results indicate that rural and urban high school students are similar in terms of knowledge about STDs, attitudes towards their prevention and also in terms of sexual behaviours. As with other studies, behaviours lagged behind knowledge and attitudes with reported condom use low. Sexual decision making was influenced mainly by the peer group. Males and females were mainly influenced by the same factors which include the willingness of their partner, the behaviours of their friends and family, concern about contracting a STD. These data emphasize the need to implement primary prevention programs for high school aged youth in rural as well as urban settings.

Sexually transmitted diseases and condoms: high school students' knowledge, attitudes and behaviours.

PIP: Researchers conducted a survey of 199 students enrolled 2 public high schools in Alberta in Canada to learn of their knowledge about sexually transmitted diseases (STDs) and knowledge, attitude, and behaviors about condoms and their use. 41% were sexually active. 41% of these students did not or rarely used condoms. 44% had =or+ 3 partners. 61% of those with =or+ 3 partners used condoms and 56% with 1 partner used them. Knowledge of STDs and condom use stood high regardless of sex or sexual activity. 93% of the boys, 80% of the girls, 88% of sexually active and 87% of nonsexually active students stated it was their responsibility to carry condoms if they are sexually active. Moreover 96% of the boys, 78% of the girls, 81% of sexually active and 91% of nonsexually active students said they would use a condom during sexual intercourse. Nevertheless males and sexually active students did express some negative attitudes towards condoms, such as reduce sensation and interference with sexual spontaneity. Nonsexually active students tended to view condom use as a negative stigma (p.05). Most students claimed to be more likely to buy condoms from condom vending machines in the rest rooms than from stores (p.05). Sexual partners had the largest influence on students, especially sexually active students, to have or not have sexual intercourse followed by concerns about STDs, friends, and family. Further, the large majority of all students, especially females and sexually active students, said they would choose their sexual partner carefully because of the concern for AIDS and other STDs. They also tended to be monogamous and avoided high risk groups. In conclusion, no reliable differences occurred between attitudes towards condoms and use or nonuse of condoms to explain behavior. Future studies should be designed to center on factors that influence sexual behavior.^ieng