How do trabeculae affect the calculation of structural properties of bone?

One difficulty that arises in an analysis of the cross-sectional properties of bone is whether to include cancellous bone in the analysis. The purpose of this paper is to determine how different amounts of cancellous bone affect the measurement of structural properties of bone cross-sections. Thirty-two tibial and femoral cross-sections were chosen at random from a series of cross-sectioned nonhuman primate bones. Geometrical properties were calculated for the cross-sections, and torsional and bending stress analyses were performed. The results suggest that the effect of including cancellous bone in the analysis is closely related to the amount of bone, where it lies within the cross-section, and the type of analysis performed. Including cancellous bone in calculations of structural properties of bone cross-sections may cause the strength and stiffness of the bone to be exaggerated.     

Some physiological observations on the uptake of d-glucose and 2-deoxy-d-glucose by starving and exponentially-growing yeasts

Some methods for measuring the uptake of sugars by yeasts were investigated critically. A study was made of the effects of starvation of Pichia pinus, Candida utilis, Saccharomyces cerevisiae and Rhodosporidium toruloides on their uptake of d-glucose and 2-deoxy-d-glucose. Marked changes in the rates of uptake of these sugars occurred during 10 h of starvation, including (a) an immediate increase of up to 75% above that for growing cells and (b) a continuous decline to as little as 4%. Each yeast behaved differently. The rates did not remain constant during the periods of starvation often used for studies on the transport of sugars into yeasts. For Pichia pinus, there were striking differences, associated with starvation, between the transport of 2-deoxy-d-glucose and d-glucose, despite evidence that the two sugars enter this yeast by means of the same carrier. Some physiological explanations for these findings are discussed.     

Sampling Bias in Roadsides: The Case of Galling Aphids on Pistacia Trees

Sampling along roadsides is convenient and is widely practiced in insect population researches. Ecological conditions in road verges are very different than those prevailing in natural habitats and they affect the annual growth of plants in semi-arid and arid regions. This in turn may improve development, survival and abundance of insects feeding on plants growing in roadsides. These trends may bias the results of sampling. To verify this assertion, we quantified the effects of growing in roadside on annual growth of Pistacia atlantica trees and Pistacia palaestina shrubs and compare two demographic indexes of nine gall-inducing aphid species on trees growing along roads with trees in the open landscape, in Israel. The annual growth of the two host plants was significantly more vigorous in roadsides than away from roads. Tests of Combined Probabilities showed that the likelihood of P. atlantica and P. palaestina to be parasitized by more galls of Fordini species is higher in roadsides than away from roads. Moreover, in the semi-dry regions of Israel, three aphid species on P. atlantica and five species on P. palaestina induced more galls in plants growing along roads than away from roads, while in the rainy Northern region, the difference was not significant between the two habitats. These results indicate a biased evaluation of population size in roadside habitat, which has to be accounted in insect–plant relation researches.     

Physical anthropological approaches to aging

The field of gerontology is remarkably diverse; yet there has been relatively little investigation of physical anthropological issues in aging research. This review explores gerontologic topics of actual and/or potential interest to physical anthropologists. The evolution of aging presents a theoretical dilemma in that postreproductively expressed traits may be outside the influence of natural selection. The physiological changes of aging comprise a diversified mosaic of physical deterioration as would be expected from an evolutionary model. Studies of prehistoric aging are limited to estimating lifespan, which may not be indicative of rate of aging. Considerable attention has been devoted to body composition and aging, and notable findings include a loss of lean tissue with age and relatively constant (though redistributing) fat mass. Osteoporosis is a major problem of aging in females, as is tooth loss in both sexes. The study of variation in rates of aging is only beginning, and a number of approaches to measuring biological age in adulthood are presented. Determining the associations of lifestyle, economic, and nutritional status with biological age may reveal sources of variation in rates of aging and may be of practical importance.     

A glycerol-free process to produce biodiesel by supercritical methyl acetate technology: An optimization study via Response Surface Methodology

In this study, fatty acid methyl esters (FAME) have been successfully produced from transesterification reaction between triglycerides and methyl acetate, instead of alcohol. In this non-catalytic supercritical methyl acetate (SCMA) technology, triacetin which is a valuable biodiesel additive is produced as side product rather than glycerol, which has lower commercial value. Besides, the properties of the biodiesel (FAME and triacetin) were found to be superior compared to those produced from conventional catalytic reactions (FAME only). In this study, the effects of various important parameters on the yield of biodiesel were optimized by utilizing Response Surface Methodology (RSM) analysis. The mathematical model developed was found to be adequate and statistically accurate to predict the optimum yield of biodiesel. The optimum conditions were found to be 399 °C for reaction temperature, 30 mol/mol of methyl acetate to oil molar ratio and reaction time of 59 min to achieve 97.6% biodiesel yield.     

The pinning method: From pinning to data preparation

The pinning method is one of the various approaches to trace the intra-annual cambium dynamics of trees along a highly resolved time axis. After a brief retrospect on preceding developmental steps, the pinning of trees and the measurement of the radial increments, formed within distinct intervals, as well as the transformation of the data necessary for subsequent statistical analyses are illustrated. Finally, some drawbacks of the pinning method are discussed.     

Applying Pulse Amplitude Modulation (PAM) fluorometry to microalgae suspensions: stirring potentially impacts fluorescence

The use of microalgae suspensions in PAM-fluorometers such as the Water-PAM (Walz GmbH, Germany) presents the problem of maintaining a homogeneous sample. The Water-PAM is marketed with an optional accessory for stirring the sample within the cuvette while in the emitter–detector (ED) unit. This stirring device can help to prevent cells from settling out of suspension over the time-course of chlorophyll-a fluorescence measurements. The ED unit was found to provide a vertically heterogeneous light environment and, therefore, cells within a single sample can exist in different quenched states. Enhancing cell movement by stirring was found to substantially influence measured fluorescence yield while performing induction curve and rapid light curve analyses. This is likely to result from relatively unquenched cells outside the main light-path moving into a higher light region and thus emitting disproportionately more fluorescence than quenched cells. Samples containing cells with high sinking rates or motile species may encounter similar (but reduced) problems. This effect can be mitigated by: (a) reducing analysis time to minimise the distance cells can sink/swim during the measurement procedure and avoiding the necessity of stirring; (b) limiting the proportion of sample outside the light path by minimising sample volume or; (c) by activating the stirrer only for short periods between saturation pulses and allowing enough time after stirring for quenching to stabilise before activation of the saturation pulse. Alternatively, modifications to the instrument providing a vertical dimension to the LED-array could resolve the issue by providing a more homogeneous light environment for the sample.     

产S-酰胺酶培养基统计学筛选与响应面优化

利用Design Expert软件中的两水平实验设计和响应面法,对发酵生产S-酰胺酶(可用于拆分2,2-二甲基环丙甲酰胺外消旋体)的培养基进行了优化。采用Plackett-Burman(PB)设计对培养基中相关影响因素的效应进行评价并筛选出了有显著效应的葡萄糖、酵母粉及2,2-二甲基环丙甲酰胺浓度,其他因素对酰胺酶产量的影响不显著。然后用旋转中心组和实验设计及响应面分析确定了主要影响因素的最佳条件,在优化的培养基中,酰胺酶产量达到168 U/L,比优化前的80 U/L提高了110.0%。     

Sampling in aerobiology. Differences between traverses along the length of the slide in Hirst sporetraps

Two years of data from four longitudinal traverses along each day's slide prepared from a continuously running Burkard sporetrap have been analyzed statistically. Using the Friedman test, a statistically significant difference was found between the four traverses, with a greater than 7% loss of pollen grains in the two outer traverses in relation to the inner. Four slides were then selected for more detailed analysis, using 18 longitudinal traverses with a 1-mm separation from the upper to the lower edge of the Melinex tape. There was found to be a progressive decline from the centre to the outside, and more than 4% of pollen grains were found outside the typical 14 mm width of the impaction orifice. There was no correlation between pollen grain size and the decline in counts from the centre to the outside. For the complete data set, there was a general rise in the diversity of pollen types with increasing sample counts, but above about 1000 pollen grains per sample there were no more than 27 pollen types found, often even fewer. A discussion is presented of whether four traverses really should be a fixing sample size, or whether it might be better to fix the total pollen count beginning with a traverse in the middle of the slide and ending with a variable number of traverses when that count is reached.     

The ‘philosophical grasp of the appearances’ and experimental microscopy: Johannes Müller’s microscopical research, 1824–1832

Romantic Naturphilosophie has been at the centre of almost every account of early nineteenth-century sciences, be it as an obstacle or as an aid for scientific advancement. The following paper suggests a change of perspective. I seek to read Naturphilosophie as one manifestation among others of a more general concern with the question of how experience enables the subject to acquire knowledge about objects. To illustrate such an approach, I focus on Johannes Müller’s early work. Here one finds two contrasting images of microscopical observation, its set-up, and the observer: the embryological study of 1830 demands a ‘philosophical grasp’ of the appearances. In contrast, the investigations of blood of 1832 are presented as a series of controlled experiments. I argue that an interpretation of this contrast in terms of an appropriation and casting aside of Naturphilosophie is not altogether convincing. Instead, both images of microscopy are manifestations of a more general problem, namely, the problem of exactly how subject and object came together in experience. I show how this concern not only shaped the methodological sensibilities particular to Müller’s embryology and the investigation of bodily liquids but also provided the epistemological principles and the target for his sense-physiological experiments. It bound Müller’s work together with Naturphilosophie and linked Naturphilosophie with other contemporaneous projects in philosophy. All of these enterprises sought to contribute to ongoing debates about how experience allowed the subject to acquire knowledge about the world.