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Recent experiments and 2D laminar plasma–fluid simulations have indicated that plasma detachment from the divertor plate is strongly tied to plasma recombination. With plasma recombination, a neutral gas blanket will form between the divertor plate and the plasma frame front. Because of plasma-neutral coupling, the plasma flow along the field lines will drive neutral gas flow with Mach number 1 and Reynolds number 1000. A compressible set of conservation and transport equations are solved with 2D mean toroidal flow and 3D turbulence effects over various toroidal cavity geometries. The radial structure of the temperature profile is determined for both turbulent and laminar flow as the flame front propagates down the toroidal cavity. Quantitative results are obtained for the increased heat transfer to the toroidal walls due to turbulence as well as radial profiles for the transport coefficients. It is found that heat loads to the toroidal walls can be increased by factors of 5–20 over that for laminar flow for the cavity geometries studied here. This increased heat transfer to the toroidal walls will lead to decreased levels of heat flux impinging on the divertor plate.

The numerical stability of thermo-lattice Boltzmann (TLBE) models is presented.The TLBE algorithm is linearized and represented in matrix form. The spectral radius of the resulting matrix is obtained by the method of powers. In particular, the numerical stability of two 2-speed 13-bit TLBE models—one based on the hexagonal lattice, and the other on a square lattice—is examined. For these two TLBE models, as a function of the energy density, the achievable Reynolds number (before the onset of grid modes) is more than an order of magnitude greater for the hexagonal grid than for the square grid.

It is found that the admixture of weak higher short-wavelength modes (several percent of the coupled power) in the spatial power spectrum of the lower-hybrid waves radiated from the waveguide grill into an inhomogeneous scrape-off-layer plasma in tokamaks has a profound influence on the ponderomotive effects of these waves. Using the barometric formula with the ponderomotive force potential for the electron density, we solve the coupling problem self-consistently for four modes using the shooting and matching method to fulfil surface impedance boundary conditions determined by infinite-grill theory. For the symmetric spectrum, below threshold, the total reflection coefficient is independent of the coupled power. Also, at these power levels, isolated density depressions (cavitons) are formed in the spatial locations where there is constructive superposition of short- and long-wavelength modes. Intense mutual mode conversion of these waves occurs at these sites. For power levels above threshold, the reflection coefficient increases until it saturates at higher powers. Numerical results are given for the 24-waveguide grill mounted on the ASDEX tokamak.

Scattering parameters (choice of incident radiation from CO2sources through far-infra-red (FIR) and millimetre sources, forward scattering and orientation angles) are sought so that the one-dimensional alpha particle distribution can be deduced directly from the experimental data. This deduction can be optimized by using orientations with incident FIR and millimetre radiation at forward scattering angles ?. Backscattering angles can be used for longer wavelength millimetre sources, although the deduction will be more difficult than for ? < 90°. The use of CO2scattering will be very difficult.

Optical frequency combs serve as the clockwork of optical clocks, which are now the best time-keeping systems in existence. The use of precise optical time and frequency technology in various applications beyond the research lab remains a significant challenge, but one that integrated microresonator technology is poised to address. Here, we report a silicon-chip-based microresonator comb optical clock that converts an optical frequency reference to a microwave signal. A comb spectrum with a 25 THz span is generated with a 2 mm diameter silica disk and broadening in nonlinear fiber. This spectrum is stabilized to rubidium frequency references separated by 3.5 THz by controlling two teeth 108 modes apart. The optical clock’s output is the electronically countable 33 GHz microcomb line spacing, which features stability better than the rubidium transitions by the expected factor of 108. Our work demonstrates the comprehensive set of tools needed for interfacing microcombs to state-of-the-art optical clocks.

We demonstrate narrow-linewidth-stimulated Brillouin lasers at 1064 nm from ultra-high-Q silica wedge disk resonators on silicon. Fundamental Schawlow–Townes frequency noise of the laser is on the order of 0.1  Hz^2/Hz. The technical noise spectrum of the on-chip Brillouin laser is close to the thermodynamic noise limit of the resonator (thermorefractive noise) and is comparable to that of ultra-narrow-linewidth Nd:YAG lasers. The relative intensity noise of the Brillouin laser also is reduced by using an intensity-stabilized pump laser. Finally, low-noise microwave synthesis up to 32 GHz is demonstrated by heterodyne of first and third Brillouin Stokes lines from a single resonator.

Due to stringent environmental regulations, wastewater treatment plants are always challenged to meet new constraints in terms of water pollution prevention. In such an effort, the number of sensors and data available in the plants have increased considerably during the last decades. However, the quality of the collected data and the sensor reliability are often poor mainly due to the hostile environment in which the measurement equipment has to function. In this work, we present the design of an array of soft-sensors to estimate the nitrate concentration in the post-denitrification filter unit of the Viikinmäki wastewater treatment plant in Helsinki (Finland). The developed sensors aim at supporting the existing hardware analysers by providing a reliable back-up system in case of malfunction. After a careful selection of suitable observations and variables to be used for calibrating the estimation models, the experimental results show the accuracy of the developed soft-sensors and their potential for an on-line implementation in the plant's control system.

The differentiation of a surface layer on the embryonal mass is one ofthe first markers for normal embryo development in Norway spruce. We havepreviously shown that this differentiation is closely interlinked with a switchin the expression pattern of Pa18, a putative lipidtransfer protein (LTP) gene. In transgenic embryos ofNorway spruce under- or overexpressing the Pa18gene under the maize ubiquitin promoter, there is no switch in the expression pattern ofthe Pa18gene and the embryos are blocked in theirdevelopment early during maturation. In this work, we describe how under- andoverexpression of Pa18affect sequential developmentalstages during somatic embryogenesis. The differentiation of somatic embryosfromproembryogenic masses is not affected, but the morphology of early somaticembryos is changed. Both under and overexpressing somatic embryos can gothrougha maturation process, although at a much lower frequency than the controlembryos. Germination is not affected by altered Pa18expression. However, plants regenerated from under and highly overexpressingsomatic embryos cannot survive prolonged culture.

MRI can be used for monitoring temperature during a thermocoagulation treatment of tumors. The aim of this study was to demonstrate the suitability of a 3D steady‐state free precession sequence (3D Fast Imaging with Steady‐State Precession, 3D TrueFISP) for MR temperature measurement at 0.23 T, and to compare it to the spin‐echo (SE) and spoiled 3D gradient‐echo (3D GRE) sequences. The optimal flip angle for the TrueFISP sequence was calculated for the best temperature sensitivity in the image signal from liver tissue, and verified from the images acquired during the thermocoagulation of excised pig liver. Factors influencing the accuracy of the measured temperatures are discussed. The TrueFISP results are compared to the calculated values of optimized SE and 3D GRE sequences. The accuracy of TrueFISP in the liver at 0.23 T, in imaging conditions used during thermocoagulation procedures, is estimated to be ±3.3°C for a voxel of 2.5 × 2.5 × 6 mm3and acquisition time of 18 s. For the SE and GRE sequences, with similar resolution and somewhat longer imaging time, the uncertainty in the temperature is estimated to be larger by a factor of 2 and 1.2, respectively. Magn Reson Med 47:940–947, 2002. © 2002 Wiley‐Liss, Inc.

All-optical logic circuits based on the polarization properties of nondegenerate four-wave mixing are proposed. Schemes to perform multiple triple-product logic functions are discussed, and it is shown that higher-level Boolean operations that involve several bits can be implemented without resorting to the standard two-input gates. As a simple illustration of the idea, a circuit that performs error correction on a (3, 1) Hamming code is demonstrated. Error-free performance (bit error rate of <10^−9) at 2.5 Gbit/s is achieved after single-error correction on the Hamming word with 50% errors.

In Finland and Norway, a uninucleate Rhizoctonia sp. is causing a root dieback disease on nursery-grown Norway spruce and Scots pine seedlings. This Rhizoctonia can be fruited under laboratory conditions and the basidial characters fit well in the species concept of Ceratobasidium bicorne, a species originally described as a moss parasite under forest conditions. Further comparison using traditional methods (cultural morphology, nuclear condition, anastomosis) has not been possible as the forest population of C. bicorne has apparently never been cultured. In the present study, we isolated DNA from a herbarium sample of C. bicorne grown on the moss Polytrichastrum formosum. Sequence analysis of the PCR-amplified rDNA region containing the internal transcribed spacer (ITS) regions and the 5.8S rDNA gene was used to examine the conspecificity of the herbarium sample and the uninucleate Rhizoctonia sp. The nucleotide sequence of the 5.8S rDNA gene was identical between the herbarium sample and five sequenced uninucleate Rhizoctonia strains. Within the uninucleate Rhizoctonia sp., the sequence identity ranged from 96.1 to 100% in ITS1 and from 99.6 to 100% in ITS2. The sequence from the herbarium sample fits well within these limits, strongly suggesting that the uninucleate Rhizoctonia sp. and C. bicorne are conspecific. Interestingly, two of the uninucleate Rhizoctonia strains produced two ITS alleles: the genetic implications are also discussed.

We present experimental results on a new method for ultrafast all-optical logic, which utilizes four-wave mixing on polarization-modulated signals. The technique allows advanced operations such as exclusive-or and three-bit addition with carry bit. Furthermore, we show that on-the-fly error-correction encoding and decoding of a simple Hamming code is achieved when these gates are used on the bits of a spectrally structured word. These gates may be suitable for logic operations in an optoelectronic front end, which moves some of the necessary computation of data to the optical domain, before detection.

Performing interventional procedures in the close proximity to an MR scanner widens the range of operations available for an optical tracking system. In order to gain the full benefits from both unrestricted use of surgical instruments outside the magnet and intraoperative imaging, a method for transferring the registration data of the optical navigator between two locations is required. An optical tracking system, which provides such a transfer method and tracks patient position during a surgical procedure, has been developed, tested, and demonstrated with two patient cases. J. Magn. Reson. Imaging 2001;13:93–98. © 2001 Wiley‐Liss, Inc.

The purpose of this clinical trial was to describe the methodology and evaluate the accuracy of optical tracking‐based magnetic resonance (MR)‐guided infiltration of the first sacral (S1) root. Thirty‐five infiltrations were performed on 34 patients with a 0.23‐T open C‐arm magnet installed in a fully equipped operation room with large‐screen (36 inches) display and optical navigator utilizing infrared passive tracking. T1 and T2 fast spin‐echo (FSE) images were used for localizing the target and fast field echo for monitoring the procedure. Saline as contrast agent in single‐shot (SS)FSE images gave sufficient contrast‐to‐noise ratio. Twenty‐four patients had unoperated L5/S1 disc herniation, and 10 had S1 root irritation after failed back surgery. Needle placement was successful in 97% of the cases, and no complications occurred. Outcome was evaluated 1–6 months (mean 2.2 months) after the procedure and was comparable to that of other studies using fluoroscopy or computed tomography guidance. MR‐guided placement of the needle is an accurate technique for first sacral root infiltration. J. Magn. Reson. Imaging 2000;12:556–561. © 2000 Wiley‐Liss, Inc.

This investigation aimed to establish noninvasive methods for endocrine monitoring of estrous cycles and pregnancy in the Indian rhinoceros. Fecal samples were collected 1–3 times per week from nonpregnant and pregnant captive females (n = 7). Enzyme immunoassays for fecal progesterone, androgen, and estrogen metabolites, respectively, were tested for their ability to determine follicular and luteal phases and to characterize endocrine profiles during pregnancy. Antibodies used were raised against pregnanediol (20α-OH-pregnanes), 20-oxo-pregnanes, epiandrosterone (17-oxo-androstanes), and total estrogens. Androgens and estrogens were found to be reliable indicators of the follicular phase, whereas 20α-OH- and 20-oxo-pregnanes were reliable indicators of luteal function. Progesterone metabolites were also reliable indicators of pregnancy, whereas 17-oxo-androstanes and estrogens were basal throughout gestation. Estrous cycles were regular throughout the year, with an average cycle length of 43.4 ± 1.5 (n = 27) days; the length of the follicular phase, as indicated by elevated estrogen levels, was 15.9 ± 1.0 days, whereas the luteal phase, as indicated by elevated 20-oxo-pregnane levels, was 19.1 ± 0.4 days. Fecal pregnane values were already increasing while follicular estrogen values were still decreasing. The length of the diestrus, indicated by basal steroid levels between declining 20-oxo-pregnanes and subsequently increasing estrogens, was 11.4 ± 1.2 days. Pregnane levels increased from the 3rd month of gestation onward and levels exceeded luteal phase concentrations ∼10 times by the 7th month of gestation onward. HPLC separation of immunoreactive fecal metabolites indicated the presence of estrone, estradiol-17β, and several 17-oxo-androstanes, 20α-OH-pregnanes, and 20-oxo-pregnanes. Concentrations of a peak with an elution profile similar to that of pregnanediol increased as pregnancy progressed. Postpartum fecal estrogen and 17-oxo-androstane concentrations in one animal indicated follicular development comparable to the follicular phase of the estrous cycle, but this was not followed by a subsequent luteal phase. In conclusion, estrous cycle and pregnancy in Indian rhinoceroses can be monitored using fecal steroid analysis. Pregnane metabolites were reliable indicators of the corpus luteum and pregnancy, whereas fecal 17-oxo-androstanes and estrogens were indicators of the follicular phase.

This article presents a miniaturized electron spin resonance (ESR) probe for deducing the position of a surgical instrument on an MR image. The ESR probe constructed was small enough to fit inside a 14-G biopsy needle sheath, and position information of the sheath could be acquired using a simple gradient sequence. The position accuracy was estimated from needle trajectories as inferred from the needle artifact, the actual physical trajectory, and measured coordinates. The probe was able to track the tip of a biopsy needle quickly (10 samples/sec) and precisely with accuracy better than ±2 mm. J. Magn. Reson. Imaging 1999;10:216–219. © 1999 Wiley-Liss, Inc.

This article presents a miniaturized electron spin resonance (ESR) probe for deducing the position of a surgical instrument on an MR image. The ESR probe constructed was small enough to fit inside a 14‐G biopsy needle sheath, and position information of the sheath could be acquired using a simple gradient sequence. The position accuracy was estimated from needle trajectories as inferred from the needle artifact, the actual physical trajectory, and measured coordinates. The probe was able to track the tip of a biopsy needle quickly (10 samples/sec) and precisely with accuracy better than ±2 mm. J. Magn. Reson. Imaging 1999;10:216–219. © 1999 Wiley‐Liss, Inc.

Be performance characteristics of semiconductor lasers for fiber telecommunication systems will be reviewed. Modulation speed, intensity noise, singlefrequency line width, and tunability are addressed. In addition, recent results concerning the same characteristics in single-frequency, tunable, fiber lasers are reviewed and compared with the semiconductor laser.

Hybridization patterns of specific cloned DNA sequences to restricted genomic DNA are analyzed in DNA fingerprinting, a technique used, e.g., for identification of individuals and for studying inheritance. We have studied the genetic variability in basket willow (Salix viminalis) by DNA fingerprinting using a bacteriophage M13 DNA probe. The five independent genotypes (clones) studied could be distinguished from each other in different enzyme digests. In three of the genotypes, restriction fragments were found that were not present in any of the other clones. The hybridization patterns to the M13 probe were somatically stable within the clones. The patterns were identical among different individuals within each clone, and remained unchanged in callus cultured in vitro, including genetically transformed callus lines. Three progeny (one individual of each) derived from two different crosses were analyzed. All the fragments seen in the offspring were present in one or both of the parents, and there are indications of homo‐ and heterozygosity in loci corresponding to some of the fragments. The results show that the method is highly sensitive and has a potential to be used in genotype identification in willow.

Effective biodegradation of organic compounds is one of the major objectives while optimizing biological drinking water treatment processes. Enhancing the biological activated carbon (BAC) filter performance with nutrient addition was studied using chemically pre-treated and ozonated lake water. Three parallel pilot-scale biofilters were operated: one with phosphorus addition, one with a mixture of inorganic nutrients addition, and one as a reference. The addition of nutrients had no statistically significant influence on the natural organic matter (NOM) removal when monitored by total organic carbon (TOC), UV absorbance, and assimilable organic carbon (AOC). However, the addition of nutrients significantly increased the heterotrophic plate count (HPC) bacteria of the filter effluent, while the adenosine triphosphate (ATP) analysis of the attached bacteria did not show any increase in BAC filters. It seemed that in BAC filters the bacterial growth was limited by phosphorus, but the increased bacteria could not attach themselves during the relatively short acclimatization period.

Supercontinuum generation is demonstrated in an on-chip silica spiral waveguide by launching 180 fs pulses from an optical parametric oscillator at the center wavelength of 1330 nm. With a coupled pulse energy of 2.17 nJ, the broadest spectrum in the fundamental TM mode extends from 936 to 1888 nm (162 THz) at −50  dB from peak. There is a good agreement between the measured spectrum and a simulation using a generalized nonlinear Schrödinger equation.