Cognitive performance of dysphasic students

The cognitive abilities of a group of dysphasic children in a special school in Finland were examined in this study to answer the following questions: Can we categorize their cognitive processing as planning, arousal-attention, simultaneous and successive processing (PASS)? The second question was concerned with detecting subgroups within the dysphasic sample in terms of PASS processes. The subjects were 60 dysphasic children in a special school. Their ages ranged from 7 to 19 years. All subjects were administered tests of planning, arousal-attention as well as simultaneous and successive processing. They were also administered the Wechsler test of intelligence for children and adults according to their ages, two sub-scales of Wechsler memory scale, as well as three ad hoc tests, cancellation task, KS persons and Rey Osterrieth copy task. The results of the factor analysis generally confirmed the emergence of the four PASS factors. As a results of cluster analysis, two subtypes of dysphasics emerged categorized as clearly high and low in the successive factor as well as relatively high and low on the simultaneous factor scores. The low-simultaneous/low-successive group was significantly lower in WISC verbal IQ the Wechsler memory scale for logical memory, and the ad hoc test of KS persons. The results were discussed, in terms of the importance of understanding the language problems typically associated with the two subtypes as well as the remedial program which will take into account their cognitive differences in spite of the fact that both groups had significant language impairment.     

Young children's causal inferences

We report 2 experiments that show a striking development between the ages of 3 and 4 years in children's ability to make causal inferences about sequences of events. The task in the first experiment was to work out what had caused the change to an object that started out as odd (noncanonical) in 1 way and ended up as odd in 2 ways--starting, for example, as a broken cup and ending as a wet and broken cup. When asked to choose the instrument that had caused the change, 3-year-olds often selected the instrument that could have caused the initial state (a hammer, in our example) and not the instrument that would produce the change. 4-year-olds hardly ever made this mistake. In the second experiment, the 3-year-olds were able to make the correct choice when the change was from a canonical to a noncanonical state (cup-wet cup) but had much more difficulty when the change was from noncanonical to canonical (wet cup-dry cup). The difference was much smaller in the older group. The first of these tasks can be solved simply on the basis of knowledge that a particular instrument can cause a particular effect without reference to the initial state. The second task requires attention to the differences between initial and final state. We conclude that the ability to make genuine causal inferences develops between the ages of 3 and 4 years.     

The madelung constant of the sodium chloride crystal lattice

An analysis of the Madelung constant of the sodium chloride crystal lattice has been made, in an effort to supplement information available in undergraduate textbooks. A method of approximation of the constant using the personal computer is presented. An erratum to this article is available at .     

What is a Species? An endless debate

Everybody is familiar with the ubiquitous term ‘species’. But what is a species? Undeniably, this is one of the most complex dilemmas in the history of biology. There is no other concept in biology as elementary yet controversial as the concept of species. In practice, a species is regarded as the fundamental unit of comparison in all biological disciplines like systematics, evolution, ecology, ethology, physiology, and genetics. However, little agreement exists in the scientific community regarding the nature of species, whether it is a real entity or a cultural artifact, its biological significance or how to delineate a species. This article is a review of the seemingly endless debate on the species concept and its implications.     

Polymorphonuclear leukocytic sialic acid and sialidase activity in obesity

The level of sialic acid in the obese polymorphonuclear leukocytes (PMNL) was found to be significantly reduced as compared to normal. Activity of sialic acid degrading enzyme, sialidase, was found to be increased in the obese state. Restoration in both sialic acid content and sialidase activity was also evidenced in the PMNL of treated obese patients.     

注意:概念、测验和教师等级评定

本文的理论部分探讨注意的性质、注意的测验和测量，以及注意缺陷的鉴定。注意具有选择性，它包含着对冲动反应的抑制和对分心的克服。第二部分讨论三项经验研究，这些研究探索了注意等级评定量表的使用，该量表由教师对儿童在课堂情境下的注意情况进行等级评定。研究发现，教师的等级评定可以预测课外情境中儿童在注意测验上的表现。这些等级评定具有显著的预测性，正如该测验的结果所表明的，教师一直关注着儿童注意的一个重要方面，即对分心的抵制。在结论性评述中，讨论了可能导向注意缺陷改善的动态测试。第三部分是附录部分，例举了若干注意力测验。     

Plate Tectonics and Europa’s Icy Shell

A unique attribute of Earth is the presence of plate tectonics. Not only does it give rise to continents, mountain chains, and ocean basins but also promotes a high level of biodiversity. It is the reason for the formation of the so-called ‘Pacific Ring of Fire’ – a belt of intense volcanic activity and a large number of earthquakes surrounding the Pacific ocean. But what drives the plate motion? Did Earth always have plate tectonics? These are some fascinating geoscientific questions. In trying to answer these questions, an effort is made to impress upon the reader the vast ocean of uncertainty, and hence the opportunity, in the field of Earth and Planetary Sciences. To make it more engaging, the article provides a peek into the long process which culminated in the present-day theory of plate tectonics on Earth. While the first half of the article focuses on subduction and its cause, the second half summarizes a recent finding made on the surface of Europa. In view of readability across disciplines, the complex subject details are kept to bare minimum.     

Toxic effects of Litsea elliptica Blume essential oil on red blood cells of Sprague-Dawley rats

Litsea elliptica Blume leaves have been traditionally used as medicinal herbs because of its antimutagenicity, che-mopreventative and insecticidal properties. In this study, the toxic effects of L. elliptica essential oil against Sprague-Dawley rat's red blood cells (RBCs) were evaluated. L. elliptica essential oil was given by oral gavage 5 times per week for 3 treated groups in the doses of 125, 250, and 500 mg/(kg body weight), respectively, and the control group received distilled water. Full blood count, RBC osmotic fragility, RBC morphological changes, and RBC membrane lipid were analyzed 28 d after the treatment. Although L. elliptica essential oil administration had significantly different effects on hemoglobin (Hb), mean cell hemoglobin concentration (MCHC), mean cell volume (MCV), and mean cell hemoglobin (MCH) in the experimental groups as compared to the control group (P<0.05), the values were still within the normal range. L. elliptica induced morphological changes of RBC into the form of echinoeyte. The percentage of echinocyte increased significantly among the treated groups in a dose-response manner (P<0.001). The concentrations of RBC membrane phospholipids and cholesterol of all treated groups were significantly lower than those of control group (P<0.001). However, the RBC membrane osmotic fragility and total proteins of RBC membrane findings did not differ significantly between control and treated groups (P>0.05). It is concluded that structural changes in the RBC membrane due to L. elliptica essential oil administration did not cause severe membrane damage.     

Epigallocatechin-3-gallate affects the growth of LNCaP cells via membrane fluidity and distribution of cellular zinc

Objective: To evaluate effects of epigallocatechin-3-gallate (EGCG) on the viability, membrane properties, and zinc distribution, with and without the presence of Zn2+, in human prostate carcinoma LNCaP cells. Methods: We examined changes in cellular morphology and membrane fluidity of LNCaP cells, distribution of cellular zinc, and the incorporated portion of EGCG after treatments with EGCG, Zn2+, and EGCG+Zn2+. Results: We observed an alteration in cellular morphology and a decrease in membrane fluidity of LNCaP cells after treatment with EGCG or Zn2+. The proportion of EGCG incorporated into liposomes treated with the mixture of EGCG and Zn2+ at the ratio of 1:l was 90.57%, which was significantly higher than that treated with EGCG alone (30.33%). Electron spin resonance (ESR) studies and determination of fatty acids showed that the effects of EGCG on the membrane fluidity of LNCaP were decreased by Zn2+. EGCG accelerated the accumulation of zinc in the mitochondria and cytosol as observed by atomic absorption spectrometer. Conclusion: These results show that EGCG interacted with cell membrane,decreased the membrane fluidity of LNCaP cells, and accelerated zinc accumulation in the mitochondria and cytosol, which could be the mechanism by which EGCG inhibits proliferation of LNCaP cells. In addition, high concentrations of Zn2+ could attenuate the actions elicited by EGCG.     

Perspective: Flicking with flow: Can microfluidics revolutionize the cancer research?

According to the World Health Organization, cancer is one of the leading causes of death worldwide. Cancer research, in its all facets, is truly interdisciplinary in nature, cutting across the fields of fundamental and applied sciences, as well as biomedical engineering. In recent years, microfluidics has been applied successfully in cancer research. There remain, however, many elusive features of this disease, where microfluidic systems could throw new lights. In addition, some inherent features of microfluidic systems remain unexploited in cancer research. In this article, we first briefly review the advancement of microfluidics in cancer biology. We then describe the biophysical aspects of cancer and outline how microfluidic system could be useful in developing a deeper understanding on the underlying mechanisms. We next illustrate the effects of the confined environment of microchannel on cellular dynamics and argue that the tissue microconfinement could be a crucial facet in tumor development. Lastly, we attempt to highlight some of the most important problems in cancer biology, to inspire next level of microfluidic applications in cancer research.