Magnetic compass orientation in the subterranean rodentCryptomys hottentotus (Bathyergidae)

Summary To test whether mole-ratsCryptomys hottentotus were able to use the magnetic field for orientation, laboratory experiments were conducted which were based on the animals' spontaneous tendency to build their nests at the same position in a circular arena. In the local geomagnetic field, the animals preferred the SE-sector. When magnetic north was turned by 120^o or by 180^o, the mole-rats changed their nest position accordingly. This clearly shows that they can use the magnetic field for direction finding.     

Effects of magnetic field on inflammation.

The effects of a 50 Hz magnetic field on experimentally-induced inflammation in rats were studied. Carrageenan edema was inhibited significantly by exposure to magnetic field for 3 h. Adjuvant-induced arthritis in rats was also suppressed by the magnetic field.     

Magnetic inclination compass: A basis for the migratory orientation of birds in the Northern and Southern Hemisphere

We conducted orientation experiments with Silvereyes,Zosterops lateralis, Australian passerine migrants, to see whether birds living in the Southern Hemisphere in a magnetic field with an upward inclination orient in the same way as birds in the Northern Hemisphere that experience a downward inclination of the magnetic field. Tested indoors in the local geomagnetic field, the birds preferred southerly directions corresponding to their migratory direction in spring. In a magnetic field with a reversed vertical component, they reversed their directional tendencies. This shows that the magnetic compass of Silvereyes also functions as an inclination compass based on the inclination of the field lines instead of the polarity.     

Individual recognition and incest avoidance in eusocial common mole-rats rather than reproductive suppression by parents

Non-reproductive females in families of eusocial common mole-rats (Cryptomys sp., Rodentia) are not suppressed by their mother, (either behaviourally or pheromonally) as is generally assumed. They do not mate with their father and brothers simply because they are not sexually attractive for them (and vice versa). The incest avoidance is based on the capability to recognize (and keep in memory for up to three weeks) each family member individually. A sterile daughter may conceive and deliver young in her parental family if given the opportunity to mate with an unfamiliar mate in a separate cage. In this way, two females may breed side by side in one family.     

The early history of ship magnetism: The Airy-Scoresby controversy

With the advent of iron-built ships in the early nineteenth century the problem of managing a magnetic compass on board presented considerable difficulty. Prominent among the early scientists who tackled the problem were George Biddell Airy and William Scoresby. Airy had provided a mechanical system, employing correctors in the form of steel magnets and wrought iron masses, by which the ship's magnetic field at the compass position is neutralized. He based his system on the concept that the magnetism acquired by an iron ship during her construction remained with the ship throughout her life. Scoresby, on the other hand, thought differently. After having conducted a thorough and systematic series of experiments on iron plates and bars, he concluded that the magnetic character of an iron ship is liable to sudden and unexpected change. Scoresby argued, therefore, that Airy's system was defective and, indeed, dangerous. The aim of this paper is to discuss the two views which brought Airy and Scoresby into a conflict which is documented in a series of letters to the editor of The Athenaeum.     

Magnetic orientation and celestial cues in migratory orientation

Summary Young birds on their first migration possess innate information on the direction of their migration route. It is present in two forms, using celestial rotation and the geomagnetic field as references. These two systems, together with information provided by factors associated with sunset, interact in a complex way to establish the migratory direction. During ontogeny, celestial rotation appears to be dominant; during migration, however, celestial cues appear to be controlled by the magnetic field. The factors associated with sunset — the view of the setting sun, the characteristic pattern of polarized light — are important secondary cues which seem to derive their directional significance from the magnetic field. Their role appears to be more variable, with possible species-specific differences. During spring migration and later autumn migrations, flying in the migratory direction is complemented by navigational processes which enable the birds to return to a specific home site known from previous stays.     

基于有限元方法的圆简直线感应电机变化气隙场瞬态特性分析

本文将电机的三维场问题转化为二维场问题，运用有限元法对圆筒直线感应电动机的二维电磁场进行了数值计算。在此理论分析的基础上，采用电磁场分析的专用软件AnsoflMaxwell2D对样机的瞬态特性进行仿真分析，得到电机运行过程中某一时刻的磁感应强度分布、磁力线、电流密度及气隙磁密等曲线；并在加额定电压条件下，研究了不同气隙下电机磁场及力特性的变化，将分析结果用来指导直线感应电机的理论研究以及本体和其控制系统的设计。     

On the time reversal invariance of classical electromagnetic theory

David Albert claims that classical electromagnetic theory is not time reversal invariant. He acknowledges that all physics books say that it is, but claims they are “simply wrong” because they rely on an incorrect account of how the time reversal operator acts on magnetic fields. On that account, electric fields are left intact by the operator, but magnetic fields are inverted. Albert sees no reason for the asymmetric treatment, and insists that neither field should be inverted. I argue, to the contrary, that the inversion of magnetic fields makes good sense and is, in fact, forced by elementary geometric considerations. I also suggest a way of thinking about the time reversal invariance of classical electromagnetic theory—one that makes use of the invariant four-dimensional formulation of the theory—that makes no reference to magnetic fields at all. It is my hope that it will be of interest in its own right, Albert aside. It has the advantage that it allows for arbitrary curvature in the background spacetime structure, and is therefore suitable for the framework of general relativity. The only assumption one needs is temporal orientability.     

场助纳米二氧化钛薄膜光催化降解甲紫的研究

纳米二氧化钛是一种重要的无机功能材料。本文采用溶胶-凝胶法制备了TiO_2薄膜,利用"场助"影响其光催化特性。光催化实验以可能具有致癌性并且难以生化降解的三苯甲烷类染料——甲紫作为降解物质,用2100型分光光度计来测量降解率,以确定电场、磁场强度对光催化特性的影响。光催化实验结果表明,外加电场(未参与水的电解)、磁场对于协助光催化降解甲紫有着明显的效果。随着外加电场、磁场强度的增加,甲紫溶液的降解率有大幅提高。反应符合一级动力学方程。     

Influence of an additional magnetic field on hornet nest architecture

Summary An additional horizontal magnetic field is lethal for adult hornets and larvae. The juvenile hornets, however, are capable of adapting to the additional magnetic field. They build combs commencing in the regions of high field intensity, and proceeding in the direction of the field intensity decrease.     

Sensory basis of bird orientation

Summary Sensory information which may be essential for the complex process of orientation of birds is described in this article. The use of vibrational, visual, chemical, olfactory, magnetic cues and their receptive mechanisms, as far as they are known, are explained. Special reference is given to the behavioral and physiological aspects of magnetic sensitivity.     

Sensory basis of bird orientation

Sensory information which may be essential for the complex process of orientation of birds is described in this article. The use of vibrational, visual, chemical, olfactory, magnetic cues and their receptive mechanisms, as far as they are known, are explained. Special reference is given to the behavioral and physiological aspects of magnetic sensitivity.     

The use of dipeptide-p-nitranilides for the study of aminopeptidase specificity.

The use of dipeptide-p-nitranilides for the study of 2 placental aminopeptidases separated on Sephadex G200 helped in establishing some regular features of their specifities. The high-molecular (320,000 daltons) one prefers Phe in position P'1 to Leu, whereas the lower-molecular aminopeptidase (145,000 daltons) prefers Leu. The high-molecular aminopeptidase splits very slowly the N-terminal Leu when Gly is in adjacent position. Leu-Gly-p-NA is therefore an inhibitor of this AP.     

Predictivism and the periodic table

This is a comment on the paper by Barnes (2005) and the responses from Scerri (2005) and Worrall (2005), debating the thesis (‘predictivism’) that a fact successfully predicted by a theory is stronger evidence than a similar fact known before the prediction was made. Since Barnes and Scerri both use evidence presented in my paper on Mendeleev’s periodic law (Brush, 1996) to support their views, I reiterate my own position on predictivism. I do not argue for or against predictivism in the normative sense that philosophers of science employ, rather I describe how scientists themselves use facts and predictions to support their theories. I find wide variations, and no support for the assumption that scientists use a single ‘Scientific Method’ in deciding whether to accept a proposed new theory.     

磁场处理对农作物产生的效应概述

大量研究表明，当生物体所处的磁场环境发生变化时，会产生各种各样的效应。本文综述了磁场处理对农作物产生的效应研究进展。     

The use of dipeptide-p-nitranilides for the study of aminopeptidase specificity

Summary The use of dipeptide-p-nitranilides for the study of 2 placental aminopeptidases separated on Sephadex G200 helped in establishing some regular features of their specifities. The high-molecular (320,000 daltons) one prefers Phe in position P'₁ to Leu, whereas the lower-molecular aminopeptidase (145,000 daltons) prefers Leu. The high-molecular aminopeptidase splits very slowly the N-terminal Leu when Gly is in adjacent position. Leu-Gly-p-NA is therefore an inhibitor of this AP.     

Resting potential of excitable neuroblastoma cells in weak magnetic fields

The mechanism by which static and low-frequency magnetic fields are transduced into biological signals responsible for reported effects on brain electrical activity is not yet ascertained. To test the hypothesis that fields can cause a subthreshold change in the resting membrane potential of excitable cells, we measured changes in transmembrane current under voltage clamp produced in SH-SY5Y neuroblastoma cells, using the patch-clamp method in the whole-cell configuration. In separate experiments, cells were exposed to static fields of 1, 5, and 75 G, to time-varying fields of 1 and 5 G, and to combined static and time-varying fields tuned for resonance of Na+, K+, Ca2+, or H+. To increase sensitivity, measurements were made on cells connected by gap junctions. For each cell, the effect of the field was evaluated on the basis of 100 trials consisting of a 5-s exposure immediately followed by a 5-s control period. In each experiment, the field had no discernible effect on the transmembrane current in the vicinity of zero current (- 50 mV voltage clamp). The sensitivity of the measuring system was such that we would have detected a current corresponding to a change in membrane potential as small as 38 microV. Consequently, if sensitivity of mammalian cells to magnetic fields is mediated by subthreshold changes in membrane potential, as in sensory transduction of sound, light, and other stimuli, then the ion channels responsible for the putative changes are probably present only in specialized sensory neurons or neuroepithelial cells. A change in transmembrane potential in response to magnetic fields is not a general property of excitable cells in culture.     

Drift of an erythrocyte flow line due to the magnetic field

Drifts of erythrocyte-flow lines due to inhomogeneous magnetic field in a laminar flow in a buffer solution are shown for the first time, and are interpreted as being due to the paramagnetism of hemoglobins included in the erythrocytes. The drifts were dependent on the hematocrit of the flowing erythrocyte suspension.     

Drift of an erythrocyte flow line due to the magnetic field

Summary Drifts of erythrocyte-flow lines due to inhomogeneous magnetic field in a laminar flow in a buffer solution are shown for the first time, and are interpreted as being due to the paramagnetism of hemoglobins included in the erythrocytes. The drifts were dependent on the hematocrit of the flowing erythrocyte suspension.     

Experimental studies of the development of migratory orientation mechanisms

Summary Recent experimental studies (since ca 1985) on the ontogeny of orientation mechanisms in migratory birds are reviewed. The processes and interactions are synthesized into a framework that may help identify critical research questions. Birds that grow up in the earth's magnetic field develop the ability to perform appropriate migratory orientation even in the absence of any experience with relevant visual cues. In two species, large changes in direction during the course of migration seem to be controlled by an endogenous time program. In one of these, the pied flycatcher (Ficedula hypoleuca), the correct magnetic orientation seems to occur only when the magnetic fields appropriate to the latitudes encountered en route were experienced at the proper seasonal time. The magnetic compass may be modified by visual experience with either the daytime or night sky. Celestial rotation may be the calibrating reference in this case, as it is in the development of the star compass. Young Savannah sparrows (Passerculus sandwichensis) learn to perform compass orientation at sunset based on polarized skylight. This compass capability seems to be calibrated by magnetic directions. Some problems of experimental design and the interpretation of results from experiments on development are discussed.