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91.
S Sambhara S Woods R Arpino A Kurichh A Tamane B Underdown M Klein K L?vgren Bengtsson B Morein D Burt 《Canadian Metallurgical Quarterly》1998,177(5):1266-1274
Here we report the isolation and characterization of mouse testicular cDNAs encoding the mammalian homologue of the Xenopus germ cell-specific nucleic acid-binding protein FRGY2 (mRNP3+4), hereafter designated MSY2. MSY2 is a member of the Y box multigene family of proteins; it contains the cold shock domain that is highly conserved among all Y box proteins and four basic/aromatic islands that are closely related to the other known germline Y box proteins from Xenopus, FRGY2, and goldfish, GFYP2. Msy2 undergoes alternative splicing to yield alternate N-terminal regions upstream of the cold shock domain. Although MSY2 is a member of a large family of nucleic acid-binding proteins, Southern blotting detects only a limited number of genomic DNA fragments, suggesting that Msy2 is a single copy gene. By Northern blotting and immunoblotting, MSY2 appears to be a germ cell-specific protein in the testis. Analysis of Msy2 mRNA expression in prepubertal and adult mouse testes, and in isolated populations of germ cells, reveals maximal expression in postmeiotic round spermatids, a cell type with abundant amounts of stored messenger ribonucleoproteins. In the ovary, MSY2 is present exclusively in diplotene-stage and mature oocytes. MSY2 is maternally inherited in the one-cell-stage embryo but is not detected in the late two-cell-stage embryo. This loss of MSY2 is coincident with the bulk degradation of maternal mRNAs in the two-cell embryo. 相似文献
92.
Swartling J Svensson J Bengtsson D Terike K Andersson-Engels S 《Applied optics》2005,44(10):1934-1941
The fluorescence spectrum measured from a fluorophore in tissue is affected by the absorption and scattering properties of the tissue, as well as by the measurement geometry. We analyze this effect with Monte Carlo simulations and by measurements on phantoms. The spectral changes can be used to estimate the depth of a fluorescent lesion embedded in the tissue by measurement of the fluorescence signal in different wavelength bands. By taking the ratio between the signals at two wavelengths, we show that it is possible to determine the depth of the lesion. Simulations were performed and validated by measurements on a phantom in the wavelength range 815-930 nm. The depth of a fluorescing layer could be determined with 0.6-mm accuracy down to at least a depth of 10 mm. Monte Carlo simulations were also performed for different tissue types of various composition. The results indicate that depth estimation of a lesion should be possible with 2-3-mm accuracy, with no assumptions made about the optical properties, for a wide range of tissues. 相似文献
93.
Vukusic J Bengtsson J Ghisoni M Larsson A Carlström CF Landgren G 《Applied optics》2000,39(3):398-401
We report on the fabrication and subsequent characterization of binary diffractive optical elements (DOE's) in InP for operation at 1.3 mum. Fresnel lenses of different focal lengths and a DOE that splits and focuses an incident beam into a 1 x 4 array of spots (optical fan-out) were fabricated. We realized the surface reliefs by patterning resist, using electron-beam lithography and etching with a chemically assisted ion beam, which produced well-defined patterns with smooth sidewalls and little if no surface roughness. The measured efficiency for the lenses was 36%. For the fan-out element the efficiency and the uniformity error were 26% and 30%, respectively. Spot sizes as small as 16 mum were measured. 相似文献
94.
The effect of pre-treatment variables such as freezing rate and method of cutting the meat, and of product surface temperature during freeze-drying as well as dehydration per se on quality were studied in multifactorial experiments. Very high freezing rate, using liquid nitrogen spray, resulted in lowered reconstitution ability after freezedrying and marked paleness of both dried and reconstituted meat, compared with freezing rates in the range spanned by conventional freezing methods. Cutting the meat before freezing impaired reconstitution ability compared with slicing it in the semifrozen state or sawing it in the frozen state before freeze-drying, but improved colour of the dry product. Comparisons between freeze-dried and frozen beef indicated a quality loss inherent in the dehydration method itself, while drying in the range of surface temperatures from +20° to +60° resulted in no appreciable difference in quality with temperature. The results obtained are in fair agreement with published data where they have been available. 相似文献
95.
The laminar jet reactor has so far only been used for studying systems without gas phase resistance. In this case however, a modified laminar jet reactor has been built, in which the gas phase resistance easily can either be theoretically calculated or experimentally determined. In the new reactor the SO2—N2 system has been studied and especially the SO2-absorption in CaCO3-slurry. 相似文献
96.
Minimisation of oxygen exposure of freeze-dried raw beef before packaging and during storage was studied in multifactorial experiments for its effect on the quality of the product, as was the effect of storage time and temperature, intramuscular fat content, and different head-space gas compositions. Exposure of the freeze-dried meat to the air before packaging under nitrogen, which is commercial practice today, clearly shortened storage life, particularly of meat with a high fat content. The effect could be counteracted by the application of an oxygen scavenging system, which proved effective at initial head-space oxygen levels as high as 4%. The use of carbon dioxide in the head-space reduced product quality compared with nitrogen or the hydrogen-nitrogen mixture employed in the oxygen scavenging system. The red meat colour as well as quality as a whole was much better preserved by cold storage and particularly frozen storage, by packaging without pre-exposure to the atmosphere or by using an oxygen scavenging system based on the reaction of oxygen with hydrogen over a palladium catalyst enclosed in the package. Of these methods, refrigerated storage is probably not a realistic solution under present commercial conditions. 相似文献
97.
Barrera T Hast A Bengtsson E 《IEEE transactions on visualization and computer graphics》2004,10(2):217-223
We show how spherical linear interpolation can be used to produce shading with a quality at least similar to Phong shading at a computational effort in the inner loop that is close to that of the Gouraud method. We show how to use the Chebyshev's recurrence relation in order to compute the shading very efficiently. Furthermore, it can also be used to interpolate vectors in such a way that normalization is not necessary, which will make the interpolation very fast. The somewhat larger setup effort required by this approach can be handled through table look up techniques. 相似文献
98.
Developments toward a microfluidic system for long-term monitoring of dynamic cellular events in immobilized human cells 总被引:1,自引:0,他引:1
Davidsson R Boketoft A Bristulf J Kotarsky K Olde B Owman C Bengtsson M Laurell T Emnéus J 《Analytical chemistry》2004,76(16):4715-4720
A microfluidic system for long-term real-time monitoring of dynamic cellular events of immobilized human cells was investigated. The luciferase reporter gene activity in the reporter cell line HFF11, based on HeLa cells, was used as the model system. The cells were immobilized on silicon flow-through microchips and continuously supplied with a cell medium at 2 microL/min while maintaining the chip at 37 degrees C. The HFF11 cell line was designed for high-throughput screening of ligands for seven-transmembrane receptors. When a ligand binds, the receptor is activated and a cascade of intracellular reactions starts, ending with the synthesis of the reporter protein Photinus luciferase. The major goal was to develop a microfluidic system for continuous long-term assaying of the intracellular reporter gene activity in real time and determine the conditions, which could minimize cells stress and hence unspecific expression of the reporter gene. In the resulting microfluidic system and assay protocol, the cell microchip could be kept and assayed for a period up to 30 h. The developed system and data outcome was compared with a corresponding microtiter plate performed with the same cell line to highlight the advantages obtained in the microfluidic format. 相似文献
99.
Udder cleft dermatitis (UCD) is a skin lesion in dairy cattle mostly located at the anterior junction between the udder and the abdominal wall or between the front quarters. Relatively little is known about causative factors for UCD, and few studies have investigated prevalence and risk factors of UCD. Therefore, the aim of this study was to investigate the prevalence of UCD in a random sample of dairy herds with freestalls and milking parlors in a county of Sweden. Thirty dairy herds participated in the study. Each herd was visited once at milking, when every third cow was investigated for presence of UCD. Associations between UCD and milk production, breed, parity, days in milk, claw health, and udder health on the herd and cow levels were also investigated. In addition, a case-control study was performed in 6 herds with a high prevalence of UCD to investigate associations between udder conformation or mange and UCD. Udder cleft dermatitis was found in 18.4% of the 1,084 cows included in the study. The within-herd cow prevalence varied between zero and 39%, with an average of 18.5%. Risk factors for UCD at the herd level were a high proportion of Swedish Red cows and a high production level. At the cow level, breed, parity, and production level were identified as risk factors. The highest risk of having UCD was found in high-producing Swedish Red cows that had calved at least 3 times. Veterinary-treated clinical mastitis was associated with UCD, but cow composite somatic cell count was not. A strong anterior udder attachment was a protective factor, but signs of mange had no association with UCD. The primary cause of UCD is still unclear, and more research is needed to identify the best ways to prevent the development of this animal welfare problem. 相似文献
100.
Henning Carlsson Emil Nordström Alexis Bohlin Per Petersson Yajing Wu Robert Collin Marcus Aldén Per-Erik Bengtsson Xue-Song Bai 《Combustion and Flame》2014
This paper reports on numerical and experimental studies of a lean premixed low swirl stabilized methane/air flame. The burner is made up of a central perforated plate and an annular swirler. A premixed methane/air mixture at an equivalence ratio of 0.62 is injected to an ambient co-flow of air through the burner under atmospheric pressure and room temperature condition with a Reynolds number of 30,000. Stereoscopic Particle Image Velocimetry (PIV) and simultaneous OH/acetone Planar Laser Induced Fluorescence (PLIF) are used to characterize the flame front and the turbulence field downstream of the burner. The flame is stabilized in the low speed central region and in the inner shear-layer vortices, where ambient air dilution to the flame is found to eventually quench the reactions downstream. Rotational Coherent Anti-Stokes Raman Spectroscopy (RCARS) measurements are carried out to characterize the temperature field and the relative oxygen mole fraction field, which enables quantification of the air dilution to the flame. The experimental data provides a challenging test case for numerical simulation models owing to the stratification of the mixture and quenching of the flame. Large eddy simulations are carried out using a three-scalar level-set G-equation flamelet model, which is shown to capture the basic flame characteristics and quenching at the trailing edge of the flame. 相似文献