On the removal of air-borne droplets by the human respiratory tract: I. The lung

Calculations as to the fate of air-borne particles in the respiratory tract are given in a paper by W. Findeisen (1935). It is the purpose of the present paper to extend and modify these calculations. The results obtained for total retention in the lungs are found to be in general agreement with published data (cf. Landahl and Herrmann, 1948). The calculated results also give information on the amounts deposited in various regions as well as the amounts retained in different fractions of expired air. The work described in this paper was done in part under contract between the Medical Division, Chemical Corps, U. S. Army, and the University of Chicago Toxicity Laboratory. Under the terms of the contract the Chemical Corps neither restricts nor is responsible for the opinions or conclusions of the author.     

A mathematical analysis of oxygen respiration in man

By means of physicomathematical models similar to those used by A. B. Chilton and R. W. Stacy (1952) formulas are obtained for the purpose of analyzing oxygen respiration in man under conditions of metabolic equilibrium. The formulas are applied to conditions involving a variety of physiological assumptions. Calculated quantities are shown to be in agreement with experimental values. A quantitative prediction is made of the fluctuation in alveolar oxygen tension over a single respiratory cycle. Finally, calculations are completed for all alveolar gases; and the over-all results are shown to be self-consistent to the degree expected in view of the simplifying approximations made. Commander, Civil Engineer Corps, U.S. Navy, attending Ohio State University under the sponsorship of the Office of Naval Research and the U.S. Naval Postgraduate School. Captain, Chemical Corps, U.S. Army, attending Ohio State University under the supervision of the U.S. Naval Postgraduate School.     

新疆生产建设兵团生态系统服务价值时空分异特征

依据2000年和2010年新疆生产建设兵团(以下简称新疆兵团)土地利用数据,利用中国陆地生态系统单位面积生态服务价值当量表,分析了新疆兵团生态服务价值的时空分异特征。结果表明:2000—2010年全兵团单位面积生态服务价值增加了204.61元hm-2a-1,年增长率为0.41%,耕地和林地生态服务价值呈增长趋势,草地、水域、湿地、未利用地生态系统服务价值呈减少趋势;2010年各师单位面积的生态系统服务价值差别很大,其基本规律为一师六师十师四师九师八师五师十四师七师二师十二师三师十三师,这与不同土地利用类型生态服务价值指数的差别和各师的土地利用程度存在密切关系;一师、二师、四师、六师、七师、八师、十师、十二师单位面积生态服务价值呈增加趋势,三师、五师、九师、十三师、十四师单位面积生态服务价值呈减少趋势;人为开垦是该区域生态系统服务价值时空动态变化的主要驱动因素。     

Circadian rhythm of air-borne bacteria and dust particles in a mouse breeding room

The circadian rhythm of air-borne bacteria and dust particles in a mice breeding room was studied at 1-hour intervals on the first, third and fifth day after accommodation of the animals. The numbers of air-borne bacteria in the room increased day by day after accommodation, and showed a circadian rhythm which went down at about noon and rose with three peaks at about 20:00, 1:00 and 8:00. The numbers of dust particles tended to decrease from day to day, and they showed almost the same circadian rhythm as the air-borne bacteria. Correlations between air-borne bacteria and dust particles were not significant for each particle level on the first day, but were significant for all the particle levels of 0.3, 1, 2, and 5 microns at the third day, and were also significant at particles levels of 0.5 micron or more on the fifth day.     

WATER RELATIONS IN THE CELL : I. THE CHLOROPLASTS OF NITELLA AND OF SPIROGYRA

Chloroplasts may contract under natural conditions and give up water to the rest of the cell, thus indicating changes in metabolism or constitution. Such contractions may be produced experimentally. In Nitella the chloroplasts are ellipsoid bodies which, under natural conditions, may contract to spheres with a loss of volume. This may be brought about by lead acetate, ferric chloride, and digitonin: the contraction may occur while the cell is alive. The contraction in lead acetate is reversible (in lead nitrate little or no contraction occurs). In Spirogyra the chloroplast is a long, spirally coiled ribbon which may contract under natural conditions to a short nearly straight rod with a loss of volume. This can be brought about by inorganic salts and in other ways while the cell is still alive.     

基于土地利用的新疆兵团与非兵团生境质量时空演变的对比

区域生境质量是生态系统健康水平的重要表征,研究土地利用变化及其引起的生境质量演变,有助于保护生物多样性、构建生态安全格局。为揭示土地利用格局变化下的新疆兵团与非兵团生境质量演变差异,本研究基于1990、2000、2010、2018年4期土地利用数据,利用InVEST模型定量评估新疆兵团与非兵团的生境质量,并分析二者时空分布异同。结果表明: 1990—2018年,兵团和非兵团土地利用类型总体较为稳定,主要表现为耕地和建设用地扩张、草地和未利用地逐渐减少。变化类型以草地、耕地相互转化,耕地转为建设用地为主;兵团的耕地和建设用地分别扩张8.3%、0.7%,草地和林地分别减少6.7%和0.3%;非兵团各地类的变化较小,草地面积减少1.5%,耕地和建设用地面积分别扩张1.2%和0.2%。研究期间,兵团和非兵团生境退化度均先降后升,生境质量整体降低。两地生境质量低值区主要分布在城镇并逐渐扩张;兵团高值区分布在盆地边缘,斑块趋于破碎化;非兵团高值区位于山地且变化较小。兵团生境质量水平高于自治区且下降速度较快。生境质量为较高或较低等级易转入中等等级,相比非兵团,兵团转入比例更高,生境破坏严重。经济发展导致两地低等级区域扩张较快,严重威胁区域生境质量。预测结果表明,2018—2035年,兵团及非兵团耕地和建设用地面积将逐渐增加,林地、草地将逐渐较少,导致生境质量水平呈下降趋势。     

Associations among the communities of soil-borne pathogens,soil edaphic properties and disease incidence in the field pea root rot complex

Plant and Soil - The sub-Antarctic cushion plant, Azorella selago, is usually hemispherical when small but frequently crescent-shaped when larger. Spatial variation in wind speed and in air-borne...     

Options for change in the NHS consultant contract.

The lead negotiators for the management and consultant sides in an NHS trust in northern England responded to debate in their trust about consultant contracts by offering to research the attitudes of their peers towards a variety of contract options. The options tested included the current contract; models already examined in the trust and elsewhere, such as time sensitive and mild performance related contracts; and some more radical and speculative possibilities, including consultants franchising their services to the trust. Beyond the predictable conclusion that consultants would prefer no change while managers desired it, a time sensitive contract emerged as having potential for successful negotiation. On the other hand, neither consultants nor managers favoured a strict performance related contract or a fee for service contract. There was a strong similarity of opinion between the two groups on the relative salary values of the options, though the consultants consistently priced these higher than the managers.     

Gone with the wind — a second blow against spontaneous generation

Christian Gottfried Ehrenberg can be considered to be the founder of the science of air-borne micro-organisms and thus aerobiology. The bicentennial of his birth (he was born on Easter Sunday, April 19th, 1795), however marks the beginning of several sciences and fields of science. He is the founder of geomicrobiology, protistology, co-founder of microbiology, scientific microscopy, neurobiology, and last not least of the theory of the Earth as a living entity, including rocks and rock deposits. The number of genera and species of bacteria, spirochaetes, fungi, diatoms, radiolaria, protozoa, and rotifera which were first described by him is in the hundreds. He is known as the discoverer and detailed describer of some of the most common bioluminescent marine organisms (Noctiluca miliaris andPeridinium), as well as the person who first deciphered the secret of the bloody hostia (Monas orBacterium prodigiosum, or more correctlySerratia marcescens), of the red snow and of the ‘meteor paper’ or ‘paper meteorites’. In this commemorative paper his work on air-borne dust and air-borne micro-organisms is reviewed.     

Effect on the heart muscle of experimental carbon monoxide poisoning.

The electron microscopic technique failed to reveal ultrastructural alterations specific for carbon monoxide poisoning. In this contract, the specificity of the lead salt detection method of calcium determination is discussed.     

生姜、食盐、乳酸对常见食品污染菌的协同抗菌防腐作用研究

目的为了降低"腌菜"等高盐食品中食盐的含量并防止食品发霉腐烂,探讨生姜、食盐、乳酸协同对空气中落下杂菌和易引起食品发霉腐烂的主要真菌的抗菌作用以及对"腌菜"的协同防腐效果。方法采用把空气中落下的杂菌培养后生长的杂菌总数计数、斜面接种真菌发育抑制和在试管内对黄瓜的防腐实验,检测生姜、食盐、乳酸的协同抗菌防腐作用。结果10%生姜、低浓度的食盐和乳酸对空中杂菌和供试易引起食品发霉腐烂的主要纯培养真菌仅有较弱的抗菌作用,但把三者组合后,对空气中杂菌和供试的大多数易引起食品发霉腐烂的真菌有明显的协同抗菌作用,能发育的空中杂菌总数明显少于各种单独应用的对照,对大多数纯培养真菌的发育阻止天数也明显多于各自单独应用的对照;三者对黄瓜也有协同防腐效果。结论生姜、食盐、乳酸能协同抑制引起食品发霉腐烂微生物的繁殖以及对"腌菜"(黄瓜)有协同防腐作用。     

Observation on the air-borne bacteria and ammonia (NS3) gas in laboratory animal facility with rotary heat exchanger]

The number of air-borne bacteria in air ducts and barrierred laboratory animal rooms with the so-called econovent rotary heat exchanger, were checked monthly during a year by the pin-hole sumpler method for air ducts and Koch method for animal rooms. Also, concentration of ammonia was checked with the same samples by gas impinger. No significantly difference in number of air-borne bacteria was seen between before and after passing the econovent. Those passing through HEPA filter was not detected. There were more air-borne bacteria in animal rooms, outside locker room and shower room than in the corridor, utensil storage, inside locker room and pass box. No ammonia were detected in the outdoor, but exhaust air duct after passing the econovent contained very small amount of ammonia. On the other hand, high concentration of ammonia were preserved in the supplying air duct, exhaust air duct and mice and rats rooms, about 86% of ammonia in exhaust air duct returned back into the supplying air duct. No influences on reproduction in mice and rats were recognized.     

Spore Dispersal and Plant Disease Gradients; a Comparison between two Empirical Models

Power law and exponential models were fitted to 325 sets of observations which described decreases with distance in deposition of air-borne or splash-borne spores, or pollen, or in amounts of plant disease caused by fungi, bacteria or viruses. There, was generally little difference between the models in the goodness of fit to these data, although deposition gradients for spores borne in splash droplets were fitted better by exponential models and gradients for fungi with air-borne spores less than 10 μm in diameter were fitted better by power law models. The exponential model has the property that the observed variable decreases by half as the distance from the source increases by a constant increment (the half-distance); this provides a measureof the gradient that is more easy to visualize than the exponent in power law model. The half-distances of gradients for air-borne pathogens were greater than those for splash-borne or soil-borne pathogens. The exponential model is easier to incorporate into models of disease development than the power law model because the boundary condition at the source (the estimated number of spores or amount of disease at the source) is finite rather than infinite. However, both these empirical models have limitations and should not be extrapolated to distances outside the observed range.     

Hearing in the African lungfish (Protopterus annectens): pre-adaptation to pressure hearing in tetrapods?

Lungfishes are the closest living relatives of the tetrapods, and the ear of recent lungfishes resembles the tetrapod ear more than the ear of ray-finned fishes and is therefore of interest for understanding the evolution of hearing in the early tetrapods. The water-to-land transition resulted in major changes in the tetrapod ear associated with the detection of air-borne sound pressure, as evidenced by the late and independent origins of tympanic ears in all of the major tetrapod groups. To investigate lungfish pressure and vibration detection, we measured the sensitivity and frequency responses of five West African lungfish (Protopterus annectens) using brainstem potentials evoked by calibrated sound and vibration stimuli in air and water. We find that the lungfish ear has good low-frequency vibration sensitivity, like recent amphibians, but poor sensitivity to air-borne sound. The skull shows measurable vibrations above 100 Hz when stimulated by air-borne sound, but the ear is apparently insensitive at these frequencies, suggesting that the lungfish ear is neither adapted nor pre-adapted for aerial hearing. Thus, if the lungfish ear is a model of the ear of early tetrapods, their auditory sensitivity was limited to very low frequencies on land, mostly mediated by substrate-borne vibrations.     

Mycosphaerella stem rot of cucumbers in the Lea Valley

Stem rot of cucumbers, caused by Mycosphaerella melonis (Passer.) Chiu & Walk, was present in Butcher's Disease Resister in every glasshouse in the Lea Valley examined in 1963 and was sometimes noticed as early as April. No correlation was detected between the severity of the disease and the type of bed used (straw bale or traditional), type of training (arch or cordon), thermostat setting, ventilation practice, date of planting, or routine fungicidal spraying practice. The disease could be transmitted on a pruning knife to any node of the plant. Infection by air-borne spores was induced experimentally. Leaves could not be infected artificially. The frequency of air-borne ascospores of the fungus showed a conspicuous evening peak. Numbers of spores were highest in wet dull weather. Dithiocarbamates appear to be the most effective fungicides now available for control.     

Crucible of fire: the Boer War and the birth of the Canadian Army Medical Corps.

Although Canada''s military physicians didn''t come to prominence until WW I and WW II, the Canadian Army Medical Corps (CAMC), the forerunner of the Royal Canadian Army Medical Corps and the current Canadian Forces Medical Service, actually had its origins in the Boer War. During that turn-of-the-century conflict, field hospitals accompanied Canadian troops to South Africa. Ian McCulloch discusses that early type of medical service and the steps that led to the creation of the CAMC.     

Wind Dispersal of Alternaria alternata, a Cause of Leaf Blight of Cotton

Introducing Alternaria alternata, the cause of blight disease of cotton plants, into a field of young healthy plants growing in rows cross-wind, yielded disease foci which were spread downwind up to 7 m from the infection sources. Only light disease incidence was found in the remainder of the field. When the disease was introduced into a field of mature cotton plants grown in rows cross-wind, randomly scattered disease foci occurred. In mature plantations where rows were parallel to the average wind direction, only limited size disease foci developed downwind, up to 16 m from the source. These foci did not developed further during the season. The number of air-borne spores of A. alternata was significantly increased by the presence of diseased cotton plants, being highest close to the diseased plants. The spores were transferred to a distance of at least 20 m. However, the number of air-borne spores significantly decreased 6 m from the infection source. Periodical trapping of air-borne spores of A. alternata in a cotton growing region for 2 years, revealed that their air dispersal is local, probably at the field level. A. alternata in a cotton growing region for 2 years, revealed that their air dispersal is local, probably at the field level. A. alternata air-borne spores were also trapped in rather low numbers regardless of the presence of infected cotton plants. However, the number of the air-borne spores trapped was dependent mainly on the average wind direction and on the Alternaria blight epidemics occurring in the fields twice a year. It is suggested that A. alternata spores are transferred by wind for short distances but are constantly present in small numbers in the atmosphere throughout the whole year. The two peaks recorded for the number of spores present in the air above cotton crops correlate with the annual two outbreaks of Alternaria blight epidemics. In addition, both wind and plant row direction affect disease development in the fields.     

Duox2-induced innate immune responses in the respiratory epithelium and intranasal delivery of Duox2 DNA using polymer that mediates immunization

Applied Microbiology and Biotechnology - Respiratory mucosa especially nasal epithelium is well known as the first-line barrier of air-borne pathogens. High levels of reactive oxygen species (ROS)...     

The half-life of a drug in relation to its therapeutic index

A procedure is given for the determination of the effective half-life of a drugin vivo with respect to an arbitrary response. If the half-life of the drug with respect to toxicity is different from that for therapy, the therapeutic index would be expected to depend on the temporal spacing of the dose. Equations are derived for this variation for a special case. This work was carried out under contract with the Medical Division of the Chemical Warfare Service.     

A Spider's Vibration Receptor: Its Anatomy and Physiology

The common house spider, Achaearanea tepidariorum, has a sensitivevibration receptor on each of its eight legs. This receptoris the tarso-metatarsal lyriform organ, and while it may notbe the only vibration receptor the spider has, it appears tobe the most sensitive. The 10 receptor units of which the senseorgan is composed are all sharply tuned to specific frequenciesbetween 60 and 1400 cps, but the sensitivity of each receptorunit depends upon the tension of the slits of the lyriform organ.Physiological experiments have shown that the tuning of thereceptors occurs only in response to air-borne sound; no discriminationis made of frequencies of web-borne vibration. One can speculatethat the high sensitivity to air-borne sound is a consequenceof the relatively poor transmission of vibration through Achaearanea'sweb.