Comprehensiveness and uniqueness of commercial databases and open access systems

Scientometrics - In this study, scholarly communication systems provided by commercial services and open access systems are examined on the basis of the comprehensiveness and uniqueness of their...     

Assessing stem cell research productivity

Honour Index (HoI), a method to evaluate research performance within different research fields, was derived from the impact factor (IF). It can be used to rate and compare different categories of journals. HoI was used in this study to determine the scientific productivity of stem cell research in the Asian Four Dragons (Hong Kong, Singapore, South Korea and Taiwan) from 1981 to 2001. The methodology applied in this study represents a synthesis of universal indicator studies and bibliometric analyses of subfields at the micro-level. We discuss several comparisons, and conclude the developmental trend in stem cell research for two decades. This revised version was published online in August 2006 with corrections to the Cover Date.     

Learning concepts in parallel based upon the strategy of versionspace

Applies the technique of parallel processing to concept learning. A parallel version-space learning algorithm based upon the principle of divide-and-conquer is proposed. Its time complexity is analyzed to be O(k log₂n) with n processors, where n is the number of given training instances and k is a coefficient depending on the application domains. For a bounded number of processors in real situations, a modified parallel learning algorithm is then proposed. Experimental results are then performed on a real learning problem, showing that our parallel learning algorithm works, and being quite consistent with the results of theoretical analysis. We conclude that when the number of training instances is large, it is worth learning in parallel because of its faster execution     

Dynamic bandwidth allocation for multimedia traffic with rate guarantee and fair access in WCDMA systems

Packet scheduling in a WCDMA system poses a new challenge due to its nature of variable bit rates and location-dependent, time-varying channel conditions. In this work, three new downlink scheduling algorithms for a WCDMA base station are proposed to support multimedia transmissions. Using a credit management and a compensation mechanism, our algorithms provide rate guarantee and fair access to mobile terminals. In particular, we propose to allow a user to simultaneously use multiple OVSF codes in a time-sharing manner, which we call a multicode, shared model. Using multiple codes allows us to compensate those users suffering from bad communication quality or even errors. The proposed schemes can tolerate a multistate link condition (compared to the typically assumed two-state, or good-or-bad, link condition) by adjusting the number of OVSF codes and the spreading factor of each code. Simulation results show that the proposed schemes do achieve higher bandwidth utilization while keeping transmission delay low.     

Gastrointestinal autonomic nerve tumour presenting as small bowel volvulus: a rare disease with a rare presentation

A 78-year-old Chinese woman presented with recurrent postprandial abdominal pain. Computerised tomography revealed a small bowel tumour causing volvulus of a segment of the small bowel. Laparotomy confirmed an extraluminal ileal tumour with partial volvulus of the involved small bowel segment. Small bowel resection was done. Histological and ultrastructural studies confirmed a gastrointestinal autonomic nerve tumour. We review the medical literature on this rare tumour.     

Functional and defective components of avian endogenous virus long terminal repeat enhancer sequences

Oncogenic avian retroviruses, such as Rous sarcoma virus (RSV) and the avian leukosis viruses, contain a strong enhancer in the U3 portion of the proviral long terminal repeat (LTR). The LTRs of a second class of avian retroviruses, the endogenous viruses (ev) lack detectable enhancer activity. By creating ev-RSV hybrid LTRs, we previously demonstrated that, despite the lack of independent enhancer activity in the ev U3 region, ev LTRs contain sequences that are able to functionally replace essential enhancer domains from the RSV enhancer. A hypothesis proposed to explain these data was that ev LTRs contain a partial enhancer that includes sequences necessary but not sufficient for enhancer activity and that these sequences were complemented by RSV enhancer domains present in the original hybrid constructs to generate a functional enhancer. Studies described in this report were designed to define sequences from both the ev and RSV LTRs required to generate this composite enhancer. This was approached by generating additional ev-RSV hybrid LTRs that exchanged defined regions between ev and RSV and by directly testing the requirement for specific motifs by site-directed mutagenesis. Results obtained demonstrate that ev enhancer sequences are present in the same relative location as upstream enhancer sequences from RSV, with which they share limited sequence similarity. In addition, a 67-bp region from the internal portion of the RSV LTR that is required to complement ev enhancer sequences was identified. Finally, data showing that CArG motifs are essential for high-level activity, a finding that has not been previously demonstrated for retroviral LTRs, are presented.     

Passive sensitization of human airways induces myogenic contractile responses in vitro

We assessed effects of passive sensitization on human bronchial smooth muscle (BSM) response to mechanical stretching in vitro. Bronchial rings were sham (control) or passively sensitized overnight by using sera from donors demonstrating sensitivity to Dermatophagoides farinae and having immunoglobulin E (IgE) concentrations of 2,600 +/- 200 U/ml. Tissues were fixed isometrically to force transducers to measure responses to electrical field stimulation (EFS) and quick stretch (QS). The myogenic response to QS was normalized to the maximal response to EFS (%EFS). The myogenic response of sensitized BSM was 47.9 +/- 10.9 %EFS to a QS of approximately 6.5% optimal length (Lo); sham-sensitized tissues had a myogenic response of 13.5 +/- 6.4 %EFS (P = 0.012 vs. passively sensitized). A QS of approximately 13% Lo in sensitized BSM caused a response of 82.8 +/- 20.9 %EFS; sham-sensitized tissues developed a response of 38.2 +/- 17.3 %EFS (P = 0.004). BSM incubated with serum from nonallergic donors did not demonstrate increased QS response (4.6 +/- 1.4 %EFS, P = not significant vs. tissue exposed to atopic sera). However, tissues incubated in sera from nonatopic donors supplemented with hapten-specific chimeric IgE (JW8) demonstrated augmented myogenic response to QS of approximately 6.5% Lo (21.9 +/- 6.2 %EFS, P = 0. 027 vs. nonatopic sera alone). We demonstrate that passive sensitization of human BSM preparations causes induction and augmentation of myogenic contractions to QS; this hyperresponsiveness corresponds to the IgE concentration in sensitizing sera.     

Health trajectories: long-term dynamics among black and white adults

Flow cytometry is a unique technology useful in the examination of effects of immunotoxic agents on target cells of the immune system. The purpose of this workshop was to provide an overview of the use of flow cytometry in new and established models of immunotoxicity, with emphasis on the potential applications, assay validation, and potential pitfalls. This overview begins with a discussion of methods useful in the assessment of Ca2+-dependent mechanisms of lymphoid cell activation in surface marker-defined human B cells, T cells, and monocytes. A discussion of the use of flow cytometry in analysis of apoptosis is also presented in this paper. The second paper presents data on the development and use of flow cytometry as an alternative to a Cr51 release assay for an assessment of cytotoxic T cell activation. The use of surface markers for characterizing and distinguishing the effects of chemical irritants from sensitizers is next presented, followed by an overview of the use of fluorescent probes to assess cell thiol status and overall oxidant-induced injury to lymphoid cells. Finally, an interlaboratory study designed to compare and evaluate the use of flow cytometry procedures in rat splenic cell subtyping is presented. Overall, these studies demonstrate the utility of flow cytometry assays in immunotoxicologic research, but further efforts are needed in the validation of many of these assays for routine use in immunotoxicologic testing.