Distribution of hydrogen peroxide and methylhydroperoxide over the Pacific and South Atlantic Oceans

The gas phase hydrogen peroxide and methylhydroperoxide concentrations were measured in the troposphere over the tropical Pacific Ocean as a component of NASA's Global Tropospheric Experiment/Pacific Exploratory Mission-Tropics A field campaign. Flights on two aircraft covered the Pacific from 70°S to 60°N and 110°E to 80°W and South Atlantic from 40°S to 15°N and 45°W to 70°E, and extending from 76 to 13,000 m altitude. H2O2 and CH3OOH have the highest concentrations at a given altitude at the equator and decrease with increasing latitude in both the northern and southern hemispheres. Above 4 km the gradient is substantially reduced for both H2O2 and CH3OOH with latitude, and at altitudes in excess of 8 km there is no latitudinal dependence. H2O2 and CH3OOH exhibit maximum mixing ratios between 1 and 2 km at all latitudes. The mean mixing ratio of H2O2 at the equator was 1600 ± 600 parts per trillion by volume (pptv) decreasing to 500 ± 250 pptv at latitudes greater than 55° north and south between 1 and 2 km altitude. CH3OOH at the equator was 1400 ± 250 pptv, decreasing to 330 ± 200 pptv at high latitudes at altitudes between 1 and 2 km. The concentration of peroxides at high latitudes in the northern hemisphere was generally a factor of 2 higher than at corresponding latitudes in the southern hemisphere. The ratio of H2O2 to CH3OOH was between 1 and 2 from 45°S to 35°N at altitudes below 4 km. Between 5° to 15°N the ratio is less than 1, due to preferential removal of H2O2 in the Intertropical Convergence Zone. Copyright 1999 by the American Geophysical Union

One-step fabrication of an organ-on-a-chip with spatial heterogeneity using a 3D bioprinting technology

Although various types of organs-on-chips have been introduced recently as tools for drug discovery, the current studies are limited in terms of fabrication methods. The fabrication methods currently available not only need a secondary cell-seeding process and result in severe protein absorption due to the material used, but also have difficulties in providing various cell types and extracellular matrix (ECM) environments for spatial heterogeneity in the organs-on-chips. Therefore, in this research, we introduce a novel 3D bio-printing method for organ-on-a-chip applications. With our novel 3D bioprinting method, it was possible to prepare an organ-on-a-chip in a simple one-step fabrication process. Furthermore, protein absorption on the printed platform was very low, which will lead to accurate measurement of metabolism and drug sensitivity. Moreover, heterotypic cell types and biomaterials were successfully used and positioned at the desired position for various organ-on-a-chip applications, which will promote full mimicry of the natural conditions of the organs. The liver organ was selected for the evaluation of the developed method, and liver function was shown to be significantly enhanced on the liver-on-a-chip, which was prepared by 3D bioprinting. Consequently, the results demonstrate that the suggested 3D bioprinting method is easier and more versatile for production of organs-on-chips.114931Nsciescopu

Clustering uncertain data using voronoi diagrams and R-tree index

We study the problem of clustering uncertain objects whose locations are described by probability density functions (pdfs). We show that the UK-means algorithm, which generalizes the k-means algorithm to handle uncertain objects, is very inefficient. The inefficiency comes from the fact that UK-means computes expected distances (EDs) between objects and cluster representatives. For arbitrary pdfs, expected distances are computed by numerical integrations, which are costly operations. We propose pruning techniques that are based on Voronoi diagrams to reduce the number of expected distance calculations. These techniques are analytically proven to be more effective than the basic bounding-box-based technique previously known in the literature. We then introduce an R-tree index to organize the uncertain objects so as to reduce pruning overheads. We conduct experiments to evaluate the effectiveness of our novel techniques. We show that our techniques are additive and, when used in combination, significantly outperform previously known methods. © 2006 IEEE.published_or_final_versio

Argon laser peripheral iridoplasty (ALPI) versus systemic intraocular pressure lowering medications as the immediate management for phacomorphic angle closure

Poster Session: Glaucoma PhenotypesPurpose: To compare the efficacy and safety of argon laser peripheral iridoplasty (ALPI) to systemic intraocular pressure (IOP) lowering medications in the immediate management of phacomorphic angle closure. Patients and methods: This was a prospective randomized controlled study conducted at a district hospital in Hong Kong, China. Consecutive cases of phacomorphic angle closure were recruited from December 2009 to December 2010. Patients received intravenous (IV) and oral carbonic anhydrase inhibitor or ALPI as the initial treatment. IV mannitol was administered in both groups for presenting IOP > 60 mmHg or IOP > 40 mmHg 2 hours post treatment. The following perimeters were compared between the 2 arms: Snellen best correct visual acuity (BCVA); duration of symptoms; presenting IOP; IOP at 15 minutes, 30minutes and hourly after treatment until IOP < 25 mmHg; post-op angle, retinal nerve fibre layer (RNFL), endothelial count, BCVA and IOP. Results: Ten consecutive cases were included in the study. Six cases received medication therapy and 4 received ALPI. The mean age was 79.7 ± 7.2 in the medical therapy group and 78.3 ± 11.0 in the ALPI group. The presenting IOP was 50.7 ± 8.4 mmHg and 50.25 ± 6.9 mmHg in the medical therapy and ALPI group respectively. The duration of phacomorphic glaucoma in the medical group was 2.8 ± 3.5 days and 0.9 ± 0.25 days in the ALPI group. In the medical therapy group, 50% (3/6) required IV mannitol and none in the ALPI group. The time taken to reduce the presenting IOP to < 25 mmHg was 115.0 ± 97.0 minutes in the medical therapy group and 18.8 ± 7.5 minutes in the ALPI group. Within the first 30minutes, the drop in IOP was 20.8 ± 13.5mmHg in the medical group and 34.8 ± 3.2mmHg in the ALPI group, representing a 41.0% and 69.3% drop in IOP respectively. The degree of peripheral anterior synechiae (PAS) formation at 3 months was 45 ± 45.3° and 22.5 ± 5° in the medical and ALPI group respectively. The RNFL, angle, endothelial count, post-op VA and IOP were comparable in both groups. Conclusion: ALPI is an effective and safe IOP lowering modality in acute phacomorphic angle closure, offering a more rapid reduction of IOP, avoiding the use of systemic carbonic anhydrase inhibitor and hyperosmotic agents, and with seemingly less PAS formation and comparable post-op results as compared to medical therapy. ALPI should replace medical therapy as first line treatment in phacomorphic angle closure especially in elderly patients cannot tolerable the side effects of systemic IOP-lowering medication.published_or_final_versio

Word learning deficit among Chinese dyslexic children

The present study examined word learning difficulties in Chinese dyslexic children, readers of a nonalphabetic script. A total of 105 Hong Kong Chinese children were recruited and divided into three groups: Dyslexic (mean age 8;8), CA control (mean age 8;9), and RL control (mean age 6;11). They were given a word learning task and a familiar word writing task. It was found that the Dyslexic group performed less well than the RL group in learning irregular words over trials but not the regular ones. Error analyses showed that the Dyslexic group made more orthographic and word association errors but less intra-wordlist interference errors than the RL control group. The Dyslexic group also performed significantly less well than both control groups in writing familiar words (e.g. their own name). These findings suggest that Chinese dyslexic children have difficulty learning new words, especially irregular ones, and retaining overlearned words in long-term memory. We conclude that Chinese dyslexic children have a specific impairment in word learning like their alphabetic counterparts. © 2006 Cambridge University Press.published_or_final_versio

Estimating incidence of developmental dyslexia in Hong Kong: What differences do different criteria make?

Based on the data of a school-referred sample of Cantonese-speaking Chinese children who met the Hong Kong criterion of dyslexia, we estimated for developmental dyslexia of Chinese children aged between 6 and 10½ in Hong Kong an incidence rate of 0.66% and a gender ratio of 3.29 boys to 1 girl over a four-year period. We also explored the differences in estimates based on this Hong Kong criterion that emphasizes cognitive markers with more conventional discrepancy-based criteria. In view of the possible biases in self-selection and underreporting in the data of the school-referred sample, we compared the figures with those derived from the sample of the normative study of the Hong Kong Test of Specific Learning Difficulties in Reading and Writing, which yielded an estimate of 9.7% in prevalence rate and boy-girl gender ratio of 2 to 1 over a one-year period. The differences in estimates based on the two samples and implications of the findings are discussed in light of the limitations of the study.postprin

Screening for Chinese children with dyslexia in Hong Kong: The use of the teachers' behaviour checklist

Primary school teachers rated the frequency of occurrence of 65 reading-related behavioural characteristics in a sample of 251 Grade 1 to Grade 6 Chinese school children in Hong Kong. These behavioural characteristics were in the areas of general performance, reading, dictation, writing, mathematics, language, memory, concentration, sequential ability, motor co-ordination, spatial orientation, and social/emotional adjustment. Of these 12 areas, 10 yielded scale scores that could distinguish children with dyslexia from those without dyslexia, identified on the basis of their performance in five domains of literacy and cognitive skills. Using a summary score derived from the 10 relevant scales, an optimal cut-off score was suggested to arrive at a balance between high sensitivity and an acceptable rate of false positives in screening for children with dyslexia. The need for cross-replication in screening children with dyslexia using the behaviour checklist with different samples of school students is emphasised.published_or_final_versio

Sequence Motifs in Transit Peptides Act as Independent Functional Units and Can Be Transferred to New Sequence Contexts

A large number of nuclear-encoded proteins are imported into chloroplasts after they are translated in the cytosol. Import is mediated by transit peptides (TPs) at the N termini of these proteins. TPs contain many small motifs, each of which is critical for a specific step in the process of chloroplast protein import; however, it remains unknown how these motifs are organized to give rise to TPs with diverse sequences. In this study, we generated various hybrid TPs by swapping domains between Rubisco small subunit (RbcS) and chlorophyll a/b-binding protein, which have highly divergent sequences, and examined the abilities of the resultant TPs to deliver proteins into chloroplasts. Subsequently, we compared the functionality of sequence motifs in the hybrid TPs with those of wild-type TPs. The sequence motifs in the hybrid TPs exhibited three different modes of functionality, depending on their domain composition, as follows: active in both wild-type and hybrid TPs, active in wild-type TPs but inactive in hybrid TPs, and inactive in wild-type TPs but active in hybrid TPs. Moreover, synthetic TPs, in which only three critical motifs from RbcS or chlorophyll a/b-binding protein TPs were incorporated into an unrelated sequence, were able to deliver clients to chloroplasts with a comparable efficiency to RbcS TP. Based on these results, we propose that diverse sequence motifs in TPs are independent functional units that interact with specific translocon components at various steps during protein import and can be transferred to new sequence contexts.11139Ysciescopu

Structure and optical properties of Lu <inf>2</inf>SiO <inf>5</inf>:Ce phosphor thin films

Luminescent, cerium doped Lu 2SiO 5 thin films with C2/c symmetry have been prepared by pulsed laser deposition (PLD) at temperatures much lower than the crystallization temperature (2150°C) of the corresponding bulk crystals. The PLD grown films show the typical luminescence resulting from the Ce 3+ 5d-4f transition. Maximum luminescence efficiency was observed for films prepared at an oxygen partial pressure of 200 mTorr at 600°C. These conditions reflect a balance between Ce 4+/Ce 3+ interconversion and the crystalline quality of the films. The results indicate that PLD offers a low temperature deposition technique for complex oxide phosphor materials. © 2006 American Institute of Physics

Vision loss following snakebite in a patient with controlled aplastic anemia

Viper venoms act mainly on blood and blood vessels. Reports of ophthalmic manifestations after snakebite include ptosis and ophthalmoplegia. In the current study, we describe a case that developed bilateral retinal and subretinal hemorrhage following snakebite. Bilateral retinal hemorrhage is a rare ocular complication of snake envenomation and has not been reported with fundus photographs in the literature so far