Implementing High Q-Factor HTS Resonators to Enhance Probe Sensitivity in 13C NMR Spectroscopy.

Nuclear magnetic resonance spectroscopy (NMR) probes using thin-film high temperature superconducting (HTS) resonators provide exceptional mass sensitivity in small-sample NMR experiments for natural products chemistry and metabolomics. We report improvements in sensitivity to our 1.5 mm 13C-optimized NMR probe based on HTS resonators. The probe has a sample volume of 35 microliters and operates in a 14.1 T magnet. The probe also features HTS resonators for 1H transmission and detection and the 2H lock. The probe utilizes a 13C resonator design that provides greater efficiency than our previous design. The quality factor of the new resonator in the 14.1 T background field was measured to be 4,300, which is over 3x the value of the previous design. To effectively implement the improved quality factor, we demonstrate the effect of adding a shorted transmission line stub to increase the bandwidth and reduce the rise/fall time of 13C irradiation pulses. Initial NMR measurements verify 13C NMR sensitivity is significantly improved while preserving detection bandwidth. The probe will be used for applications in metabolomics.

13C-Optimized HTS NMR RF Coil Design at 21.1 T.

We present the design of a novel high-temperature superconductor double-sided racetrack resonator for a 13C optimized nuclear magnetic resonance (NMR) transmitter/receiver coil. The coils operate in a 21.1 T magnet and accommodate a 3 mm × 6.2 mm cross-section rectangular sample tube. The design includes the incorporation of revised finger lengths to improve the homogeneity of current density across the fingers, a new laser trimming approach for adjusting the resonance frequency, and improved ability to shift higher-order modes for suitability in 1H/13C NMR probes. Resonator design methodology, simulations and experimental results are presented.

[Results of a complex evaluation of accommodative asthenopia in using different-design video monitors]. / Rezul'taty kompleksnoi otsenki akkomodativnoi astenopii pri rabote s videomonitorami razlichnoi konstruktsii.

Eighty volunteer computer operators were examined experimentally under the conditions of working with different-type video monitors, i.e. electron-beam (EB), liquid-crystal (LC), including different visual loads (typing, computer games, and gaze fixation). Experiments lasted for as long as 6 hours. The absolute accommodation volume (AAV), relative accommodation reserve (RAR) and ergograms were comparatively evaluated. A lower AAV was registered in all types of visual loads under the conditions of using different-type monitors, and it made up 0.27-1.08 diopters. A maximum reduction of AAV was detected for gaze fixation and while working with liquid-crystal monitors. The RAR reduction ranged from 0.31 to 0.63 diopters. A maximum RAR reduction was noted for gaze fixation and while using the electronic-beam monitors. The nature of changed ergography curves occurred within the interval between I and IIb types of ergograms. In case of typing, the ergogram deviations were registered to a greater extent for the liquid-crystal monitors. The value of deviations for computer games was bigger, at the experiment end, for EB rather than for LC.

Incidence of leukemia and other cancers in Down syndrome subjects in Israel.

Epidemiologic data have confirmed the high susceptibility of persons with Down syndrome (DS) to leukemia. The question of proneness to other kinds of cancer is still open. In this study we reassessed the incidence rates of leukemia and other malignancies in Israeli DS subjects, based on the total population. The target population consisted of all DS subjects in Israel in the period of 1948--1995. Due to incompleteness of data, the target population was not fully achieved, thus the study population was divided into 2 subgroups: subjects born in Israel between 1979 and 1995 (registry group) and currently or past-institutionalized subjects born before 1979 (institution group). The cohort was linked with the Cancer Registry, and cancer cases that had been diagnosed through December 1995 were subsequently identified. Observed incidence rates were compared with expected rates in the general population. Standardized incidence ratios (SIR) and 95% confidence intervals (CI) were computed for each disease category. Analyses were performed separately for each subgroup of the study population. In the registry group, 7 cancer cases were observed, compared with 1.5 expected (SIR = 4.67, 95% CI 1.9--9.6), all leukemia cases. For the institution group a total of 17 cancer cases were observed, compared with 12.8 expected. These included 4 cases of leukemia (SIR = 6.90, 95% CI 1.90--17.70). An excess of gastric cancer in male subjects (SIR = 11.9, 95% CI 1.3--42.9) was also observed. Significant excess of leukemia in DS population in Israel is in accordance with previously published data. An excess of gastric cancer in DS male subjects born before 1979, which has not been reported before, should be further explored.

Risk factors for infant mortality in Down's syndrome: a nationwide study.

The aim of this study was to assess risk factors for the excessive infant mortality rates (IMR) of infants with Down's syndrome (DS). The study population included all 847 Jewish DS births in Israel during 1979-83 and 1987-91. Cases were identified through the National DS Registry. Data were abstracted from hospitalisation records. Ninety-one per cent of the DS diagnoses were confirmed by a cytogenetic analysis. The DS IMR were 24.3 times higher than in the general population. Major risk factors affecting DS IMRs were health status, time period of birth and residential arrangement of the infant. Other known risk factors for infant mortality, such as young maternal age, high birth order and low birthweight, had a weaker impact on IMR in the DS population. Our results imply that the current better survival of infants with DS is a function of the changing attitude towards this population. The study identifies a potential for further reduction in the mortality rates of DS infants, provided there is willingness to adopt a more active and supportive treatment and further changes in ethical codes of the public.

[The current problems of electromagnetic safety in computer classes]. / Aktual'nye problemy élektromagnitnoi bezopasnosti v komp'iuternykh klassakh.

He paper presents the data on the present-day situation in the computer classes in general educational schools to show electromagnetic safety. It shows that most of 37 classes do not satisfy the requirement of electromagnetic safety and proposes modes of elimination of this danger.

[Topical problems of hygienic certification of computers]. / Aktual'nye problemy gigienicheskoi sertifikatsii komp'iuterov.

The paper provides evidence that while making a hygienic certification of computers it is necessary to rely not only on their physical and technical data, but on the characteristics obtained by defining the integral physiological parameters of the quality of displayed information perception. According the state standards CaH [symbol: see text] 2.2.2.54-96, their hygienic certification requires differential assessment of computers with the age-specific features of users (pre-school and young school children, middle- and old-aged schoolchildren, adults). It is proposed that CaH [symbol: see text] 2.2.2.54-96 should be supplemented by a regulation on choice of special working places with appropriate protective devices for the children of a risk group.