Determination of aqueous two-phase system phase-forming components in the presence of bovine serum albumin

In the current work, the quantification of different poly(ethylene glycol) (PEG)–potassium phosphate/sodium citrate aqueous two-phase system (ATPS) phase-forming components was investigated by using conductivity and refractive index measurements. For this purpose, refractive index and conductivity calibration curves were obtained for ATPS at different pH values in the presence of different bovine serum albumin (BSA) concentrations. Whereas BSA had no effect on the conductivity, it had a considerable effect on the refractive index. Finally, a convenient dilution of the samples prior to the ATPS constituent determination is needed to ensure no significant influence from BSA.     

PEDIGREE ERROR DUE TO EXTRA‐PAIR REPRODUCTION SUBSTANTIALLY BIASES ESTIMATES OF INBREEDING DEPRESSION

Understanding the evolutionary dynamics of inbreeding and inbreeding depression requires unbiased estimation of inbreeding depression across diverse mating systems. However, studies estimating inbreeding depression often measure inbreeding with error, for example, based on pedigree data derived from observed parental behavior that ignore paternity error stemming from multiple mating. Such paternity error causes error in estimated coefficients of inbreeding (f) and reproductive success and could bias estimates of inbreeding depression. We used complete “apparent” pedigree data compiled from observed parental behavior and analogous “actual” pedigree data comprising genetic parentage to quantify effects of paternity error stemming from extra‐pair reproduction on estimates of f, reproductive success, and inbreeding depression in free‐living song sparrows (Melospiza melodia). Paternity error caused widespread error in estimates of f and male reproductive success, causing inbreeding depression in male and female annual and lifetime reproductive success and juvenile male survival to be substantially underestimated. Conversely, inbreeding depression in adult male survival tended to be overestimated when paternity error was ignored. Pedigree error stemming from extra‐pair reproduction therefore caused substantial and divergent bias in estimates of inbreeding depression that could bias tests of evolutionary theories regarding inbreeding and inbreeding depression and their links to variation in mating system.     

Correction for Covariate Measurement Error in Nonparametric Longitudinal Regression

Summary We introduce a correction for covariate measurement error in nonparametric regression applied to longitudinal binary data arising from a study on human sleep. The data have been surveyed to investigate the association of some hormonal levels and the probability of being asleep. The hormonal effect is modeled flexibly while we account for the error‐prone measurement of its concentration in the blood and the longitudinal character of the data. We present a fully Bayesian treatment utilizing Markov chain Monte Carlo inference techniques, and also introduce block updating to improve sampling and computational performance in the binary case. Our model is partly inspired by the relevance vector machine with radial basis functions, where usually very few basis functions are automatically selected for fitting the data. In the proposed approach, we implement such data‐driven complexity regulation by adopting the idea of Bayesian model averaging. Besides the general theory and the detailed sampling scheme, we also provide a simulation study for the Gaussian and the binary cases by comparing our method to the naive analysis ignoring measurement error. The results demonstrate a clear gain when using the proposed correction method, particularly for the Gaussian case with medium and large measurement error variances, even if the covariate model is misspecified.     

Comparison of micrometer‐ and scanning electron microscope‐based measurements of avian eggshell thickness

ABSTRACT The study of avian eggshell structure, including composition, pigmentation, thickness, and strength, has important ecological and economic implications. Previous investigators have used a variety of techniques to derive either direct measures or indirect estimates of eggshell thickness. Assessing the repeatability and method agreement of different techniques is necessary to permit comparison of eggshell thickness values from different studies on various genetic stocks, populations, and species. We recorded and analyzed measurements of eggshell thickness using two methods, micrometers and scanning electron microscopy (SEM), for several Palaeognathae and Neognathae taxa, including nonpasserines and passerines. Applying a tolerance‐interval approach, we found that repeatability of measurements for eggs with thinner shells (<300 μm, all Neognathae taxa) was worse than for eggs with thicker shells (Palaeognathae taxa), but was still statistically and biologically reasonable given that the relative magnitude of intramethod agreements was <11%. Our results support previous predictions that measurements made using a micrometer are comparable to those made using SEM. This finding is particularly important given the relative ease and cost efficiency of the micrometer method. Importantly, these new analyses can be used to validate the use of published data from previous studies of micrometer‐based eggshell thickness for both intra‐ and interspecific comparisons.     

Kinetics of NO3(-) net fluxes in Pinus pinaster, Rhizopogon roseolus and their ectomycorrhizal association, as affected by the presence of NO3(-) and NH4+

The impact of mineral N supply, N-free or NO3(-) with or without NH4+, on the subsequent uptake of NO3(-) by maritime pine seedlings associated with the ectomycorrhizal fungus Rhizopogon roseolus was studied using ion-selective microelectrodes. NO3(-) net fluxes into N-starved non-mycorrhizal short roots (NMSRs) were low and measurable only over the NO3(-) concentration range of 0-70 microM. The simple kinetics observed in those roots may reflect the dominant operation of a high-affinity NO3(-) transport system (HATS) which is constitutive. NO3(-) pretreatment increased the NO3(-) net fluxes and led to a complex kinetics that may reflect the operation of other HATS. A simple kinetics was observed in plants pre-incubated at high NH4+ concentration. In contrast, NO3(-) uptake kinetics presented only one saturation phase in the fungus, whether associated with the plant or not. NO3(-) uptake was greater after a pretreatment in N-free or NO3 (-) solution, but NH4+ pretreatment led to a threefold reduction in NO3 (-) uptake. These results suggest that the regulation of NO3(-) transport systems varies between the host and the fungal partner. This variation is likely to contribute to the positive effect of mycorrhizal association on N uptake in plants when the N supply is low and fluctuating.     

Potential exposure assessment errors associated with body-worn RF dosimeters

Personal exposure meters for assessing exposure to RF electric or magnetic fields are subject to errors associated with perturbations of the fields by the presence of the human body. Although these alterations are complex they are not completely unpredictable. This article concludes that this error in a common worst-case scenario could reach up to 30 dB and therefore is of concern for exposure assessment. We present several guidelines to address this issue and a useful insight into the overall problem based on finite-difference time-domain simulations and experimental verification.     

Evaluating climatic and non-climatic influences on ion chemistry in natural and man-made lakes of Nebraska,USA

Conductivity and major ion chemistry data were analyzed for a suite of Nebraska (USA) natural lakes, reservoirs, sand pits, and barrow pits to evaluate the magnitude of climatic versus non-climatic influence on ionic concentration and composition. In both natural lakes and sand and barrow pits, conductivity is positively related to longitude and reflects decreasing effective moisture from east to west. Reservoirs showed no relationship between lake conductivity and location, probably because the reservoirs are very strongly influenced by groundwater and surface water inflow and have shorter residence times relative to the other lake types. At smaller spatial scales, conductivity among natural lakes is variable. Lakes that are at low elevation within a groundwater flow system were fresh, because of substantial input of fresh groundwater. In contrast, lakes at high elevation exhibited a wide range of conductivity, probably because of differences in the degree of connection to groundwater and surface to volume ratio impacts on evaporation rates. Differences also were evident among natural lakes in terms of their response to seasonal changes in precipitation. Sub-saline and saline lakes showed more seasonal variation in conductivity than freshwater lakes, and lakes in the more arid part of the state showed larger responses to precipitation change than those in areas to the east that receive higher precipitation.     

链霉菌M-1菌株所产抑菌活性物质特性的初步研究

用链霉菌M-1菌株所产的抑菌物质进行稳定性试验和极性试验,稳定性试验表明该菌株连续传代10次后遗传性稳定,且发酵液在100℃处理60 min,紫外线照射3 min和在碱性条件下处理后其对病原指示菌的抑菌活性基本不减。极性试验表明该物质属于弱碱性水溶性抗生素。本研究为进一步对该抑菌活性物质分离提取工艺和其在实践上的应用,提供了有益的试验数据。     

关于提高血气分析仪测量精度的探讨

血气分析已广泛用于昏迷、休克、严重外伤的危急病人的血液酸碱度、氧分压、二氧化碳分压的测量。测量数据的准确性至关重要。本文对与测量精度有关的几个环节如计量检定、质控与定标、样本采集与测量、日常维护与故障处理进行探讨,提出提高血气分析精度的解决方案。     

A novel device to monitor small changes in underwater distances

Abstract. This study describes a technique to record small (1 cm) distance changes or movements occurring in seawater using a simple electronic circuit and miniature ball electrodes. This low-cost technique was designed to directly measure such changes in a broad range of experiments involving small marine invertebrates while minimizing the mechanical loading of the structures of interest. The circuit detects and amplifies small changes in the resistance of seawater between two electrodes as the distance between them varies; these are then converted to voltage changes. After calibrating the output of the device with known distance measurements, it was evaluated using a test organism by monitoring and recording the body flushing behavior of the sea squirt, Styela plicata . Electrodes were sewn to the tunic at the base of the atrial siphon and changes in its diameter were recorded >24-h periods. Using ∼3-cm-tall sea squirts, the distance between the electrodes expanded and contracted with a range of 5.5 mm during rhythmic flushings. Flushes occurred on average every 4.1 min and showed a rapid initial contraction, followed by a slower expansion while refilling. Attaching electrodes to the tunic had little mechanical or behavioral effect; the untouched control specimen had similar flushing rates. The movement monitor circuit is stable, sensitive, and performed well in full-strength seawater experiments where good spatial and high temporal resolution, low inertial loading, and low noise were required. The technique, as shown here, can be used to record a wide range of animal movements and further suggested modifications of the circuit may suit a broad range of other experimental situations.