427 research outputs found
Are visual skills unimportant to Chinese readers in primary-school level?
No full textPURPOSE: Despite the visual complexity of Chinese words increases across grades, it is surprising that visual skills accounted for significant variance in Chinese word reading for kindergarten readers (Ho & Byrant, 1999; Ho & Byrant, 1997, Mcbride-Chang and Ho, 2000) but not for primary school readers (Chen and Wong, 1991; Hu and Catts, 1998; Huang and Hanley, 1997). This study aimed at re-exploring visual word recognition of primary school readers by adding in an intermediate variable, the knowledge of radicals, which is the basic orthographic unit of Chinese language. METHODS AND RESULTS: Study 1 explored the relationships among visual skill, orthographic skill and word recognition for 384 readers from Primary One to Four. After partialling out the effects of age and IQ, orthographic skills accounted uniquely for 5% of the variance in word recognition. Visual skills did not predict word recognition, but accounted for 4% of the variance in orthographic skills. These findings showed that radical knowledge is important in word recognition. Visual skills are employed in decoding radicals, rather than decoding words as a whole. This difference further implies an implicit perceptual decomposition of words into radicals during visual processing. Study 2 compared 30 dyslexic, 30 chronological-age matched and 30 reading-level matched readers on a variety of visual and orthographic tasks. The dyslexic group performed significantly worse than the CA group on all the tasks. Combined with the results from Study 1, it is speculated that the word decoding difficulties of dyslexic readers might stem from poor understanding of radicals, which in turn is visually dependent. To further explore why the dyslexic group perform poorly on visual tasks, Study 3 employed the eye-tracking technique on a visual discrimination task for 10 dyslexic readers, 10 CA control and 5 RL control. Compared with the CA group, the dyslexic group had significantly more fixations and longer fixation duration on the target form, and exhibited more sequential comparisons between their chosen form and the distracters. It is speculated that the dyslexic readers need more cognitive resources on identifying features of a visual form, and are more prone to the interference of visually-similar distracters. CONCLUSION: Radicals play an important role in the visual recognition of Chinese words. Readers start with learning single characters made up of one or few radicals, and progress into compound characters of multiple radicals. This may account for the importance of visual skills in word reading for kindergarten readers, but not for primary school readers. Reading difficulties in Chinese readers may stem from inefficient visual processing of radicals and interference of visually-similar radicals. These further hinder the development of orthographic skills, such as recognizing the positional and functional regularity of radicals, and subsequently leads to poorer word decoding performance.The 16th Annual Meeting of the Society for the Scientific Studies of Reading (SSSR 2009), Boston, MA., 25-27 June 2009
Stroop Interference, rapid automatized naming and reading ability in Chinese children
No full textRapid automatized naming was a robust predictor of Chinese word reading among kindergarten and elementary grade students (Chan, Ho, Tsang, Lee, & Chung, 2006; Tong, McBride-Chang, Shu, & Wong, 2009; Yeung et al., 2011). The present study attempted to examine the relationships among Stroop interference, rapid automatized naming and reading ability among 106 Hong Kong children aged 7-10. Each participant was administered the Raven’s Standard Progressive Matrices, a general processing speed task, rapid naming tasks, a phonological awareness task, a Stroop Test, and Chinese reading ability measures (a Chinese word reading task and a one-minute Chinese text reading task). Multiple regression results showed that the measure of Stroop interference significantly predicted Chinese text reading but not word reading after controlling for the contributions of age, IQ, processing speed and phonological awareness. The measure of Stroop interference and processing speed explained significant amount of unique variance in performance in rapid automatized naming tasks after controlling for age, IQ and phonological awareness. However, the measure of Stroop interference did not contribute unique amount of variance to Chinese reading measures in the context of rapid automatized naming. These findings were discussed in light of the relationship between automaticity and reading development among Chinese children
A catalogue of the Bryophytes of Sulawesi, Indonesia
No full textA first catalogue of the mosses (Bryophyta s.str), liverworts (Marchantiophyta), and hornworts (Anthocerotophyta) of Sulawesi (formerly Celebes), Indonesia, is presented. The checklist is based on published records and a few unpublished collections. In total, 476 species are listed, including 340 of moss (in 145 genera), 134 of liverwort (in 46 genera), and 2 of hornwort (in 2 genera). One liverwort and four moss species are only known from Sulawesi. As compared with other major islands of Malesia, the number of bryophyte species recorded from Sulawesi is low. Species numbers of liverworts and mosses from Borneo, New Guinea, and the Philippines are about two to six times higher. Several large bryophyte genera are poorly represented on Sulawesi or are absent, due presumably to undercollecting. This catalogue will hopefully stimulate more work on the neglected bryophyte flora of Sulawesi. Two names, Calyptrochaeta perlimbata (Dixon) B.C.Tan & B.-C.Ho, comb. nov., and Macromitrium novorecurvulum B.C.Tan & B.-C.Ho, nom. nov, are newly proposed
A catalogue of the Bryophytes of Sulawesi, Indonesia
No full textA first catalogue of the mosses (Bryophyta s.str), liverworts (Marchantiophyta), and hornworts (Anthocerotophyta) of Sulawesi (formerly Celebes), Indonesia, is presented. The checklist is based on published records and a few unpublished collections. In total, 476 species are listed, including 340 of moss (in 145 genera), 134 of liverwort (in 46 genera), and 2 of hornwort (in 2 genera). One liverwort and four moss species are only known from Sulawesi. As compared with other major islands of Malesia, the number of bryophyte species recorded from Sulawesi is low. Species numbers of liverworts and mosses from Borneo, New Guinea, and the Philippines are about two to six times higher. Several large bryophyte genera are poorly represented on Sulawesi or are absent, due presumably to undercollecting. This catalogue will hopefully stimulate more work on the neglected bryophyte flora of Sulawesi. Two names, Calyptrochaeta perlimbata (Dixon) B.C.Tan & B.-C.Ho, comb. nov., and Macromitrium novorecurvulum B.C.Tan & B.-C.Ho, nom. nov, are newly proposed
Characteristics of Cell Surface Hydrophobictiy of Candida albicans
No full text의학과/석사[영문]
[한글]
Candida albicans의 병인기전에 관계된 요인들로는 균주가 생산하는 exoenzyme과 toxin
들, 상피세포에의 부착능 그리고 germ tube형성는 등의 여러 가지 요인들이 있으며, 이런
요인들은 병인기전에 서로 복합되어 연관됨으로써 C.albicans의 병원성이 결정된다. C.
albicans의 세포표면 소수성(cell surface hydrophobicity, CSH)은 세포표면 사이의 친화
성에 영향을 주어 숙주 상피세포에의 부착과정과 연관되어 병원서에 관여할 것으로 추측
되나, 그 기전은 아직 확실하지 않다.
본 연구는 C. albicans를 대상으로 온도 및 배지의 산도, 탄소원과 성장 및 증식에 따
른 배양조건이 CSH의 발현에 미치는 영향과, CSH에 따른 구강 상피세포에의 부착능과 ger
m tube 생성능 그리고 세포벽의 전자 현미경 검사 및 마우스 치사능을 측정함으로써 C. a
lbicans의 CSH와 병원성과의 연관성을 밝히고자 하였으며 다음과 같은 결과를 얻었다.
1. C. albicans의 배양온도 25℃의 조건이 37℃보다 높은 CSH를 나타내었고, 시험균주
6주중 1주에서는 CSH의 차이가 없었다. CSH 발현의 배지 최적 산도는 pH 5 및 6이며 배양
배지의 탄소원 glucose, galactose, maltose와 50mM 및 500mM의 농도 차이에 따른 CSH 발
현의 차이는 없었다. 그리고 성장 및 증식과정중 증식유도기를 지나면서 성장정지기까지
는 CSH가 높게 발현되어 일정하게 유지되며, 균의 사멸이 시작되면서 CSH가 낮아지는 결
과를 나타내었다.
2. 구강 상피세포 부착능은 C. albicans를 25℃에서 배양한 군보다 37℃에서 배양한 군
이 더 높으며 CSH와는 역상관관계를 나타내었다. 배양 배지의 탄소원 maltose, galactose
, glucose군의 순으로 부착능이 높고, 50mM보다는 500mM의 고농도에서 배양한 군이 높은
부착능을 나타 내었다.
3. C. albicans의 CSH가 높을수록 germ tube 형성능이 높았다.
4. 투과 전자현미경 소견중에서 CSH가 가장 낮게 발현된 C.albicans의 세포벽에서만 (C
. albicans YMC-11, 배양온도 37℃), 최외각에 fibrogranular층이 보이며, electron dens
e츠이 더 두껍게 관찰되었다.
5. 마우스 치사능 성적은 CSH가 높게 발현되는 25℃에서 배양한 yeast세포를 접종한 마
우스 군이 37℃에서 배양한 yeast 세포를 접종한 군보다 치사효과가 빠르게 나타났으며,
CSH가 높게 발현된 C. albicans 균주(YMC-20)를 접종한 마우스 군이 CSH가 낮게 발현된
균주(YMC-11)를 접종한 마우스 군보다 높은 치사 효과를 나타내었다.
이상의 결과를 종합해 볼 때 C. albicans의 CSH는 성장 및 증식의 지표가 될 수 있으며
, C. albicans의 병원성을 나타내는 특성중의 하나로 사료된다.
Characteristics of Cell Surface Hydrophobicity of Candida albicans
Kyoung Ho Lee
Department of Medical Science, The Graduate School, Yonsei University
(Directed by Professor Choon Myung Koh, Ph.D.)
The effect of cultural conditions on cell surface hydrophobicity (CSH) of Candida
albicans was examined. And the relationship between CSH and adherence to buccal
epithelial cell, activity of germ tube formation, cell walll ultrastructure and
mouse lethality in experimental strains of C. albicans was studied.
C. albicans cells grown at 25℃ were more hydrophobic than cells grown at 37℃.
the optimal pH for CSH expression was a range of pH 5-6. On CSH expression of yeast
cells, the effect of three sugars as a carbon source (glucose, galactose and
maltose), as well as two different concentrations (50 mM and 500mM), was
investigated. In each case, yeast cells were similar levesls of CSH. The CSH
expression of both hydrophilic cells(C. albicans YMC-11) and hydrophobic
cells(YMC-56) were persistent from acceleration phase to stationary phase and
decreased as death rate of the yeast cells increased, but accelerated in the course
of initial yeast cells growth.
Adherence to human buccal epithelial cells was enhanced to varing extents
according to the carbon source used. Maltose was the most effective sugar of those
tested; yeasts harvested from medium containing 500 mM of different sugars showed
more greater adherence to epithelial cells than cells grown in medium with 50mM of
sugars.
Yeast cells grown at 37℃ adheres to epithelial cells to a significantly greater
degree than were grown at 25℃. Higher negative correlation was obtained between
CSH and adherence when the isolates grown at both 25 and 37℃. A significantly
positive correlation was obtained between CSH and activity of germ tube formation.
On electron microscopy, the fibrogranular material, a type of adhesin, revealed
only in hydrophobic cells(C. albicans YMC-11) grown at 37℃.
Mice were injected intravenously with with C. albicans YMC-20 grown at 25 or
37℃. Cells grown at 25℃ were more hydrophobic than were grown at 37℃. The more
hydrophobic cells grown at 25℃ allow to kill mice faster than less hydrophphobic
cells grown at 37℃. Interestingly, the more hydrophobic organisms(C. albicans
YMC-20) were more virulent than less hydrophobic organisms(YMC-11).
These results indicate that CSH expression is important in C.albicans growth and
CSH may represent an virulence of C. albicans.restrictio
Understanding developmental dyslexia in Chinese: From basic research to identification and intervention
No full textUnderstanding reading disability in the Chinese language: from basic research to intervention
No full text- …
