A biomechanical model of the upper airways for simulating laryngoscopy

This paper describes a three-dimensional finite element model of the human upper airways during rigid laryngoscopy. In this procedure, an anaesthetist uses a rigid blade to displace and compress the tongue of the patient, and then inserts a tube into the larynx to allow controlled ventilation of the lungs during an operation. A realistic model of the main biomechanical aspects involved would help anaesthetists in training and in predicting difficult cases in advance. For this purpose, the finite element method was used to model structures such as the tongue, ligaments, larynx, vocal cords, bony landmarks, laryngoscope blade, and their inter-relationships, based on data extracted from X-ray, MRI, and photographic records. The model has been used to investigate how the tongue tissue behaves in response to the insertion of the laryngoscope blade, when it is subjected to a variety of loading conditions. In particular, the mechanical behaviour of the soft tissue of the tongue was simulated, from simple linear elastic material to complex non-linear viscoelastic material. The results show that, within a specific set of tongue material parameters, the simulated outcome can be successfully related to the view of the vocal cords achieved during real laryngoscopies on normal subjects, and on artificially induced difficult laryngoscopy, created by extending the upper incisors teeth experimentally.     

A simplified method of casting the macroscopic airways of lungs

A technique for preparing casts of the macroscopic airways of mammalian lungs, which is both simplified and inexpensive in comparison with previous techniques, is described. The models are accurate, durable and flexible, and clearly demonstrate the orientation and branching pattern of the bronchial tree. The nature of the procedure also extends the availability of casts to laboratories or individuals with limited instrumentation and/or funding. Preliminary results using this technique to inject the lungs and certain air sacs of birds are also discussed.     

A method for estimating the relative importance of characters in cladistic analyses

The method of character importance ranking (CIR) is proposed here as a means for estimating the relative "importance" of characters in cladistic analyses, especially those based on morphological features. CIR uses the weighting variable to incrementally remove one character at a time from the analysis, and then evaluates the impact of the removal on the shape of the cladogram. The greater the impact, the more important the character. The CIR method for determining which characters drive the shape of a particular cladogram has several applications. It identifies the characters with the strongest (though not necessarily most accurate) signal in a cladistic analysis; it permits the informed prioritization of characters for further investigation via genetic, developmental, and functional approaches; and it highlights characters whose definition, scoring, independence, and variation should be reviewed with particular care. The application of CIR reveals that at least some cladograms depend entirely on a single character.     

Strandedness of DNA at 92% relative humidity

The existing X-ray diffraction data of DNA at 92% relative humidity are different from those obtained from the B form at 66% relative humidity. Though the intensity spots are less well defined in the former, they can nevertheless be fitted with a four stranded helical model.     

Label-free relative quantification method for low-abundance glycoproteins in human serum by micrOTOF-Q

In this study, a label-free relative quantification strategy was developed for quantifying low-abundance glycoproteins in human serum. It included three steps: (1) immunodepletion of 12 high-abundance proteins, (2) enrichment of low-abundance glycoproteins by multi-lectin column, (3) relative quantification of them between different samples by micrOTOF-Q. We also evaluated the specificity and efficiency of immunodepletion, the accuracy of protein quantification and the possible influence of immunodepletion, glycoprotein enrichment, trypsin digestion and peptide ionization on quantification. In conclusion, the relative quantification method can be effectively applied to the screening of low-abundance biomarkers.     

Suitability of capacitive sensors for measuring relative humidity in anesthetic gas systems]

A capacitive sensor was tested for its suitability for measuring relative humidity in an anaesthetic gas circuit. The valvo sensor PH1 was tested using various different anaesthetic gas mixtures. Measuring accuracy was influenced neither by such volatile anaesthetics as isoflurane and halothane, nor by oxygen or nitrous oxide. The response time of the sensor depends on its position within the gas, and in the most favourable case is about 3 minutes. The sensor is readily incorporated within an existing gas circuit. The linearity of the characteristic curve must be corrected by external electronic compensation to avoid measuring problems in the lower humidity range.     

Bacterial pleomorphism and competition in a relative humidity gradient

The response of different bacterial species to reduced water availability was studied using a simple relative humidity gradient technique. Interestingly, distinct differences in morphology and growth patterns were observed between populations of the same species growing at different relative humidity. Gram-positive cocci increased in cell size as they approached humidity growth limits and staphylococcal species started growing in tetrad/cubical formations instead of their normal grape-like structures. Gram-negative rods displayed wave-like patterns, forming larger waves as they became increasingly filamentous at low humidity. In contrast, cells of the Gram-positive bacterium Bacillus subtilis became shorter, curved, and eventually almost coccoid. Moreover, B. subtilis started to sporulate at low humidity. The altered morphology and/or growth patterns of bacteria growing at low humidity might be more ecologically relevant than their textbook appearance at high humidity since their natural habitats are often dry. Transmission electron microscopic analyses revealed that staphylococci grown at low humidity have significantly thickened cell walls, which may explain why these cells displayed increased resistance to vancomycin. We conclude that our relative humidity gradient technique is widely applicable for investigating effects of relative humidity on microbial survival, growth and competitive success at solid–air interfaces, making it a versatile tool in microbial ecology.     

A new drift-flux model for particle transport and deposition in human airways

Particle deposition and transport in human airways isfrequently modeled numerically by the Lagrangian approach. Current formulations of such models always require some ad hoc assumptions, and they are computationally expensive. A new drift-flux model is developed and incorporated into a commercial finite volume code. Because it is Eulerian in nature, the model is able to simulate particle deposition patterns, distribution and transport both spatially and temporally. Brownian diffusion, gravitational settling, and electrostatic force are three major particle deposition mechanisms in human airways. The model is validated against analytical results for three deposition mechanisms in a straight tube prior to applying the method to a single bifurcation G3-G4. Two laminar flows with Reynolds numbers 500 and 2000 are simulated. Particle concentration contour deposition pattern, and enhancement factor are evaluated. To demonstrate how the diffusion and settling influence the deposition and transport along the bifurcation, particle sizes from 1 nm to 10 microm are studied. Different deposition mechanisms can be combined into the mass conversation equation. Combined deposition efficiency for the three mechanisms simultaneously was evaluated and compared with two commonly used empirical expressions.     

Effect of relative humidity on the airborne survival of rhinovirus-14

Rhinovirus-14, suspended in tryptose phosphate broth supplemented with uranine (physical tracer) and an antifoam, was aerosolized by use of a Collison nebulizer. The aerosols were held in a rotating drum with the relative humidity at either the low (30 +/- 5%), medium (50 +/- 5%), or high (80 +/- 5%) level at 20 +/- 1 degrees C. An all-glass impinger was used to recover the virus from the air in the drum, with the first air sample being collected after a 15-min period of aerosol stabilization. Subsequent air samples were withdrawn at 2, 4, 8, and 14 h after stabilization of the aerosol. At the low and medium relative humidity levels, the infectivity of the airborne virus was rapidly lost and less than 0.25% could be detected in the first air sample. At the high RH level, however, the airborne virus had a half-life of 13.7 +/- 1.91 h and nearly 30% of the input infectious virus could be detected in the drum air even after 24 h of aerosolization. These findings suggest that under certain environmental conditions, notably high relative humidity, air may act as a vehicle for the spread of rhinovirus infections.     

湿度对三角新小卷蛾实验种群生长的影响

在相对湿度(RH)为55%、65%、75%、85%和95%条件下,观察湿度对三角新小卷蛾Olethreutes leucaspis Meyrick各虫态生长、发育及存活的影响,组建三角新小卷蛾实验种群生命表。结果表明:在RH为55%-95%条件下,三角新小卷蛾卵、幼虫、蛹和世代的发育历期在RH为85%时最短,发育历期分别为1.67、12.46、7.67和25.42 d。高湿条件下卵、幼虫和蛹的存活率较高。三角新小卷蛾各虫态发育历期、存活率与相对湿度呈抛物线关系。在RH为55%-95%条件下该虫内禀增长力(rm)均大于0,种群趋势指数(I)均大于1,该虫种群呈增长趋势。三角新小卷蛾发育适宜的RH为75%。     

The effect of relative humidity on the shape ofBacillus apiarius spores

Bacillus apiarius spores have been examined at relative humidities between 99% and 12% in a scanning electron microscope modified to enable wet specimens to be studied. The spores have also been studied both wet and dry with an interference microscope. Their shape remains rectangular whether wet or dry. A calculation of the effect of an osmotic pressure change of about 200 atm upon the maximum deflection of the longest side of the spore shows that the deflection is less than 4.5 nm. The shape of the spore therefore is not markedly affected by a change from dry to wet and the shape will remain as it was when the coat was initially formed, unless the coat is weakened by some chemical attack. The refractive index of the coat material is 1.532–1.536.     

Effect of relative humidity, atmospheric temperature, and suspending medium on the airborne survival of human rotavirus

The Wa strain of human rotavirus, grown in MA-104 cells, was suspended either in tryptose phosphate broth or feces from a case of rotaviral diarrhea. It was then aerosolized into a rotating drum using a Collison nebulizer. The drum air was sampled using an all-glass impinger containing tryptose phosphate broth as collecting fluid. At 20 +/- 1 degree C, the virus aerosolized from tryptose phosphate broth was found to survive best at 50 +/- 5% relative humidity, where its half-life was 44.2 +/- 6.3 h. At 30 +/- 5% and 80 +/- 5% relative humidity, the half-life of the virus was 24.5 +/- 3.5 and 3.8 +/- 1.0 h, respectively. At 6 +/- 1 degree C, the airborne survival of the virus at the mid and low relative humidity levels was further enhanced, but at the high relative humidity it remained very similar to that seen at 20 +/- 1 degree C. When aerosols of fecally suspended human rotavirus were held at 20 +/- 1 degree C with 50 +/- 5% relative humidity, nearly 80% of the airborne virus particles remained infectious even at the aerosol age of 24 h. These findings may help in our understanding of the epidemiology of rotaviral infections.     

Ripe pollen carbohydrate changes in Trachycarpus fortunei: the effect of relative humidity

Pollen of the palm Trachycarpus fortunei was kept at 25°C and relative humidities (RH) of 20, 55 and 98%. Changes in viability, water content and carbohydrates were measured over 2–17 days. Water content remained almost constant at 20 and 50% RH and increased dramatically at 98%. Pollen viability and germination rate remained almost constant over 14 days at 20% RH and decreased to about 2% after 7–9 days at 55% and to even less at 98% RH. Although the three experimental conditions were constant, qualitative and quantitative variations in pollen carbohydrates were recorded, even after pollen had lost its viability. The quantities of mono-, di- and polysaccharides varied with the period of pollen storage at the various RH. The greatest changes in glucose, fructose and sucrose content were recorded at 55 and 98% RH. At these relative humidities, maximum glucose and fructose content and minimum sucrose content occurred at maximum water content. Starch was not present in mature pollen but appeared and peaked after 7–9 days of pollen storage at 55 and 98%. Appearance of starch coincided with an increase in pectin content. PAS-positive cytoplasmic polysaccharides showed an increasing trend at 20% RH. A relation was found between pollen viability, water content and monosaccharide content. Pollen viability and germination capacity remained high at 20% RH for 14 days. At this relative humidity, pollen water, glucose and fructose contents remained almost constant, while sucrose reached its maximum value. The fluctuations of more complex carbohydrates (starch, pectins and PAS-positive cytoplasmic polysaccharides) were less easy to interpret. Changes observed under experimental conditions could simulate processes occurring in nature during pollen presentation and dispersal.