bluuebunny/crossref_metadata_2025 huggingface dataset:
The ATM/ATR Signaling Effector Chk2 Is Targeted by Epstein-Barr Virus Nuclear Antigen 3C To Release the G
2
/M Cell Cycle Block
Authors: Choudhuri Tathagata , Verma Subhash C. , Lan Ke , Murakami Masanao , Robertson Erle S.
Published: April 2007

Epstein-Barr virus (EBV) infects most of the human population and persists in B lymphocytes for the lifetime of the host. The establishment of latent infection by EBV requires the expression of a unique repertoire of genes. The product of one of these viral genes, the EBV nuclear antigen 3C (EBNA3C), is essential for the growth transformation of primary B lymphocytes in vitro and can regulate the transcription of a number of viral and cellular genes important for the immortalization process. This study demonstrates an associated function of EBNA3C which involves the disruption of the G
2
/M cell cycle checkpoint. We show that EBNA3C-expressing lymphoblastoid cell lines treated with the drug nocodazole, which is known to block cells at the G
2
/M transition, did not show a G
2
/M-specific checkpoint arrest. Analyses of the cell cycles of cells expressing EBNA3C demonstrated that the expression of this essential EBV nuclear antigen is capable of releasing the G
2
/M checkpoint arrest induced by nocodazole. This G
2
/M arrest in response to nocodazole was also abolished by caffeine, suggesting an involvement of the ATM/ATR signaling pathway in the regulation of this cell cycle checkpoint. Importantly, we show that the direct interaction of EBNA3C with Chk2, the ATM/ATR signaling effector, is responsible for the release of this nocodazole-induced G
2
/M arrest and that this interaction leads to the serine 216 phosphorylation of Cdc25c, which is sequestered in the cytoplasm by 14-3-3. Overall, our data suggest that EBNA3C can directly regulate the G
2
/M component of the host cell cycle machinery, allowing for the release of the checkpoint block.
Indirect Regulation of CD4 T-Cell Responses by Tumor Necrosis Factor Receptors in an Acute Viral Infection
Authors: Singh Anju , Wüthrich Marcel , Klein Bruce , Suresh M.
Published: April 2007

Despite the well-recognized importance of CD4 T-cell help in the induction of antibody production and cytotoxic-T-lymphocyte responses, the regulation of CD4 T-cell responses is not well understood. Using mice deficient for TNF receptor I (TNFR I) and/or TNFR II, we show that TNFR I and TNFR II play redundant roles in down regulating the expansion of CD4 T cells during an acute infection of mice with lymphocytic choriomeningitis virus (LCMV). Adoptive transfer experiments using T-cell-receptor transgenic CD4 T cells and studies with mixed bone marrow chimeras indicated that indirect effects and not direct effects on T cells mediated the suppressive function of TNF on CD4 T-cell expansion during the primary response. Further studies to characterize the indirect effects of TNF suggested a role for TNFRs in LCMV-induced deletion of CD11chidendritic cells in the spleen, which might be a mechanism to limit the duration of antigenic stimulation and CD4 T-cell expansion. Consequent to enhanced primary expansion, there was a substantial increase in the number of LCMV-specific memory CD4 T cells in the spleens of mice deficient for both TNFR I and TNFR II. In summary, our findings suggest that TNFRs down regulate CD4 T-cell responses during an acute LCMV infection by a non-T-cell autonomous mechanism.
Association of Vaccinia Virus Fusion Regulatory Proteins with the Multicomponent Entry/Fusion Complex
Authors: Wagenaar Timothy R. , Moss Bernard
Published: April 2007

The proteins encoded by the A56R and K2L genes of vaccinia virus form a heterodimer (A56/K2) and have a fusion regulatory role as deletion or mutation of either causes infected cells to form large syncytia spontaneously. Here, we showed that syncytia formation is dependent on proteins of the recently described entry fusion complex (EFC), which are also required for virus-cell fusion and low-pH-triggered cell-cell fusion. This finding led us to consider that A56/K2 might prevent fusion by direct or indirect interaction with the EFC. To test this hypothesis, we made a panel of recombinant vaccinia viruses that have a tandem affinity purification tag attached to A56, K2, or the A28 EFC protein. Interaction between A56/K2 and the EFC was demonstrated by their copurification from detergent-treated lysates of infected cells and identification by mass spectrometry or Western blotting. In addition, a purified soluble transmembrane-deleted form of A56/K2 was shown to interact with the EFC. Tagged A56 did not interact with the EFC in the absence of K2, nor did tagged K2 interact with the EFC in the absence of A56. The finding that both A56 and K2 are required for efficient binding to the EFC fits well with prior experiments showing that mutation of either A56 or K2 results in spontaneous fusion of infected cells. Because A56 and K2 are located on the surface of infected cells, they are in position to interact with the EFC of released progeny virions and prevent back-fusion and syncytia formation.
Chromatin Profiling of Epstein-Barr Virus Latency Control Region
Authors: Day Latasha , Chau Charles M. , Nebozhyn Michael , Rennekamp Andrew J. , Showe Michael , Lieberman Paul M.
Published: April 2007

Epstein-Barr virus (EBV) escapes host immunity by the reversible and epigenetic silencing of immunogenic viral genes. We previously presented evidence that a dynamic chromatin domain, which we have referred to as the latency control region (LCR), contributes to the reversible repression of EBNA2 and LMP1 gene transcription. We now explore the protein-DNA interaction profiles for a few known regulatory factors and histone modifications that regulate LCR structure and activity. A chromatin immunoprecipitation assay combined with real-time PCR analysis was used to analyze protein-DNA interactions at ∼500-bp intervals across the first 60,000 bp of the EBV genome. We compared the binding patterns of EBNA1 with those of the origin recognition complex protein ORC2, the chromatin boundary factor CTCF, the linker histone H1, and several histone modifications. We analyzed three EBV-positive cell lines (MutuI, Raji, and LCL3459) with distinct transcription patterns reflecting different latency types. Our findings suggest that histone modification patterns within the LCR are complex but reflect differences in each latency type. The most striking finding was the identification of CTCF sites immediately upstream of the Qp, Cp, and EBER transcription initiation regions in all three cell types. In transient assays, CTCF facilitated EBNA1-dependent transcription activation of Cp, suggesting that CTCF coordinates interactions between different chromatin domains. We also found that histone H3 methyl K4 clustered with CTCF and EBNA1 at sites of active transcription or DNA replication initiation. Our findings support a model where CTCF delineates multiple domains within the LCR and regulates interactions between these domains that correlate with changes in gene expression.
Crystal Structures of Major Envelope Proteins VP26 and VP28 from White Spot Syndrome Virus Shed Light on Their Evolutionary Relationship
Authors: Tang Xuhua , Wu Jinlu , Sivaraman J. , Hew Choy Leong
Published: April 2007

White spot syndrome virus (WSSV) is a virulent pathogen known to infect various crustaceans. It has bacilliform morphology with a tail-like appendage at one end. The envelope consists of four major proteins. Envelope structural proteins play a crucial role in viral infection and are believed to be the first molecules to interact with the host. Here, we report the localization and crystal structure of major envelope proteins VP26 and VP28 from WSSV at resolutions of 2.2 and 2.0 Å, respectively. These two proteins alone account for approximately 60% of the envelope, and their structures represent the first two structural envelope proteins of WSSV. Structural comparisons among VP26, VP28, and other viral proteins reveal an evolutionary relationship between WSSV envelope proteins and structural proteins from other viruses. Both proteins adopt β-barrel architecture with a protruding N-terminal region. We have investigated the localization of VP26 and VP28 using immunoelectron microscopy. This study suggests that VP26 and VP28 are located on the outer surface of the virus and are observed as a surface protrusion in the WSSV envelope, and this is the first convincing observation for VP26. Based on our studies combined with the literature, we speculate that the predicted N-terminal transmembrane region of VP26 and VP28 may anchor on the viral envelope membrane, making the core β-barrel protrude outside the envelope, possibly to interact with the host receptor or to fuse with the host cell membrane for effective transfer of the viral infection. Furthermore, it is tempting to extend this host interaction mode to other structural viral proteins of similar structures. Our finding has the potential to extend further toward drug and vaccine development against WSSV.
MEK1/2 Inhibitors Block Basal and Transforming Growth Factor β1-Stimulated JC Virus Multiplication
Authors: Ravichandran Veerasamy , Jensen Peter N. , Major Eugene O.
Published: April 2007

The multiplication of the human neurotropic polyomavirus JC virus (JCV) is regulated by cell membrane receptors and nuclear transcription factors. Signaling pathways also play a role in determining the extent to which JCV can productively infect cells. These data show that constitutively active MEK1 protein (CA-MEK1), overexpressed in cultures of human glia, supports a substantial increase in late JCV protein (Vp-1) synthesis. The specificity of this pathway was indicated by no significant enhancement of JCV multiplication through activation of other components of mitogen-activated protein kinase pathways such as p38, Jun N-terminal protein kinase, and protein kinase A. Further evidence supporting the importance of signaling in JCV infection came from addition of transforming growth factor β1 (TGF-β1), which stimulated a 200% increase of Vp-1 expression. Specific MEK1/2 inhibitors, flavenoid PD98059 and U0126, decreased the basal and TGF-β1-stimulated Vp-1 expression by 95% or more. TGF-β1 is known to phosphorylate/activate Smad DNA binding proteins that could subsequently bind or increase binding to JCV promoter sequences, linking the effects of signaling with JCV transcriptional regulation. The effectiveness with which MEK1/2 inhibitors block JCV multiplication provides insight that may contribute to development of compounds directed against JCV.
Biological and Immunological Relations among Human Parvovirus B19 Genotypes 1 to 3
Authors: Ekman Anna , Hokynar Kati , Kakkola Laura , Kantola Kalle , Hedman Lea , Bondén Heidi , Gessner Matthias , Aberham Claudia , Norja Päivi , Miettinen Simo , Hedman Klaus , Söderlund-Venermo Maria
Published: April 2007

The human parvovirus B19 is now divided into three genotypes: type 1 (prototype), type 2 (A6- and LaLi-like), and type 3 (V9-like). In overall DNA sequence, the three virus types differ by ∼10%. The most striking DNA dissimilarity, of >20%, is observed within the p6 promoter region. Because of the scarcity of data on the biological activities and pathogenetic potentials of virus types 2 and 3, we examined the functional characteristics of these virus types. We found the activities of the three p6 promoters to be of equal strength and to be most active in B19-permissive cells. Virus type 2 capsid protein VP2, alone or together with VP1, was expressed with the baculovirus system and was shown to assemble into icosahedral parvovirus-like particles, which were reactive in the hemagglutination assay. Furthermore, sera containing DNA of any of the three B19 types were shown to hemagglutinate. The infectivities of these sera were examined in two B19-permissive cell lines. Reverse transcription-PCR revealed synthesis of spliced B19 mRNAs, and immunofluorescence verified the production of NS and VP proteins in the infected cells. All three genotypes showed similar functional characteristics in all experiments performed, showing that the three virus types indeed belong to the same species, i.e., human parvovirus B19. Additionally, the antibody activity in sera from B19 type 1- or type 2-infected subjects (long-term immunity) was examined with homo- and heterologous virus-like particles. Cross-reactivity of 100% was observed, indicating that the two B19 genotypes comprise a single serotype.
Identification of a Novel C-Terminal Cleavage of Crimean-Congo Hemorrhagic Fever Virus PreG
N
That Leads to Generation of an NS
M
Protein
Authors: Altamura Louis A. , Bertolotti-Ciarlet Andrea , Teigler Jeffrey , Paragas Jason , Schmaljohn Connie S. , Doms Robert W.
Published: April 2007

The structural glycoproteins of Crimean-Congo hemorrhagic fever virus (CCHFV; genus
Nairovirus
, family
Bunyaviridae
) are derived through endoproteolytic cleavage of a 1,684-amino-acid M RNA segment-encoded polyprotein. This polyprotein is cotranslationally cleaved into the PreG
N
and PreG
C
precursors, which are then cleaved by SKI-1 and a SKI-1-like protease to generate the N termini of G
N
and G
C
, respectively. However, the resulting polypeptide defined by the N termini of G
N
and G
C
is predicted to be larger (58 kDa) than mature G
N
(37 kDa). By analogy to the topologically similar M segment-encoded polyproteins of viruses in the
Orthobunyavirus
genus, the C-terminal region of PreG
N
that contains four predicted transmembrane domains may also contain a nonstructural protein, NS
M
. To characterize potential PreG
N
C-terminal cleavage events, a panel of epitope-tagged PreG
N
truncation and internal deletion mutants was developed. These constructs allowed for the identification of a C-terminal endoproteolytic cleavage within, or very proximal to, the second predicted transmembrane domain following the G
N
ectodomain and the subsequent generation of a C-terminal fragment. Pulse-chase experiments showed that PreG
N
C-terminal cleavage occurred shortly after synthesis of the precursor and prior to generation of the G
N
glycoprotein. The resulting fragment trafficked to the Golgi compartment, the site of virus assembly. Development of an antiserum specific to the second cytoplasmic loop of PreG
N
allowed detection of cell-associated NS
M
proteins derived from transient expression of the complete CCHFV M segment and also in the context of virus infection.
The pro-inflammatory effects of low-toxicity low-solubility particles, nanoparticles and fine particles, on epithelial cells in vitro: the role of surface area
Authors: Monteiller Claire , Tran Lang , MacNee William , Faux Steve , Jones Alan , Miller Brian , Donaldson Ken
Published: April 2007

Objective:Rats exposed to high airborne mass concentrations of low-solubility low-toxicity particles (LSLTP) have been reported to develop lung disease such as fibrosis and lung cancer. These particles are regulated on a mass basis in occupational settings, but mass might not be the appropriate metric as animal studies have shown that nanoparticles (ultrafine particles) produce a stronger adverse effect than fine particles when delivered on an equal mass basis.

Methods:This study investigated whether the surface area is a better descriptor than mass of LSLTP of their ability to stimulate pro-inflammatory responses in vitro. In a human alveolar epithelial type II-like cell line, A549, we measured interleukin (IL)-8 mRNA, IL8 protein release and glutathione (GSH) depletion as markers of pro-inflammatory effects and oxidative stress after treatment with a range of LSLTP (fine and nanoparticles) and DQ12 quartz, a particle with a highly reactive surface.

Results:In all the assays, nanoparticle preparations of titanium dioxide (TiO2-np) and of carbon black (CB-np) produced much stronger pro-inflammatory responses than the same mass dose of fine TiO2and CB. The results of the GSH assay confirmed that oxidative stress was involved in the response to all the particles, and two ultra-fine metal dusts (cobalt and nickel) produced GSH depletion similar to TiO2-np, for similar surface-area dose. As expected, DQ12 quartz was more inflammatory than the low toxicity dusts, on both a mass and surface-area basis.

Conclusion:Dose–response relationships observed in the in vitro assays appeared to be directly comparable with dose–response relationships in vivo when the doses were similarly standardised. Both sets of data suggested a threshold in dose measured as surface area of particles relative to the surface area of the exposed cells, at around 1–10 cm2/cm2.

These findings are consistent with the hypothesis that surface area is a more appropriate dose metric than mass for the pro-inflammatory effects of LSLTP in vitro and in vivo, and consequently that the high surface area of nanoparticles is a key factor in their inflammogenicity.
A simple diagnostic model for ruling out pneumoconiosis among construction workers
Authors: Suarthana Eva , Moons Karel G M , Heederik Dick , Meijer Evert
Published: April 2007

Background:Construction workers exposed to silica-containing dust are at risk of developing silicosis even at low exposure levels. Health surveillance among these workers is commonly advised but the exact diagnostic work-up is not specified and therefore may result in unnecessary chestxray investigations.

Aim:To develop a simple diagnostic model to estimate the probability of an individual worker having pneumoconiosis from questionnaire and spirometry results, in order to accurately rule out workers without pneumoconiosis.

Methods:The study was performed using cross-sectional data of 1291 Dutch natural stone and construction workers with potentially high quartz dust exposure. A multivariable logistic regression model was developed using chestxray with ILO profusion category ⩾1/1 as the reference standard. The model’s calibration was evaluated with the Hosmer–Lemeshow test; the discriminative ability was determined by calculating the area under the receiver operating characteristic curve (ROC area). Internal validity of the final model was assessed by a bootstrapping procedure. For clinical application, the diagnostic model was transformed into an easy-to-use score chart.

Results:Age 40 years or older, current smoker, high-exposure job, working 15 years or longer in the construction industry, “feeling unhealthy” and FEV1were independent predictors in the diagnostic model. The model showed good calibration (a non-significant Hosmer–Lemeshow test) and discriminative ability (ROC area 0.81, 95% CI 0.74 to 0.85). Internal validity was reasonable; the optimism corrected ROC area was 0.76. By using a cut-off point with a high negative predictive value the occupational physician can efficiently detect a large proportion of workers with a low probability of having pneumoconiosis and exclude them from unnecessaryxray investigations.

Conclusions:This diagnostic model is an efficient and effective instrument to rule out pneumoconiosis among construction workers. Its use in health surveillance among these workers can reduce the number of redundantxray investigations.
Short-term effects of ozone air pollution on ischaemic stroke occurrence: a case-crossover analysis from a 10-year population-based study in Dijon, France
Authors: Henrotin J B , Besancenot J P , Bejot Y , Giroud M
Published: April 2007

Objective:To evaluate the association between air pollutants and the occurrence of acute stroke from 10-year population-based study.

Methods:The daily stroke count was obtained from Dijon Stroke Register between March 1994 and December 2004. The register recorded all first-ever strokes among residents of Dijon (150 000 inhabitants) in France, using standard diagnostic criteria. Pollutant concentrations (SO2, CO, NO2,O3and PM10) were measured hourly. A bi-directional case-crossover design was used to examine the association between air pollutant and stroke onset. The conditional logistic regression model included the meteorological parameters (temperature, relative humidity), influenza epidemics and holidays.

Results:The authors collected 493 large artery infarcts, 397 small artery infarcts, 530 cardio-embolic infarcts, 67 undeterminate infarcts, 371 transient ischaemic attacks and 220 haemorrhagic strokes. For single-pollutant model and for a 10 mg/m3increase of O3exposure, a positive association was observed only in men, over 40 years of age, between ischaemic stroke occurrence and O3levels with 1-day lag, (OR 1.133, 95% CI 1.052 to 1.220) and 0-day lag (OR 1.058, 95% CI 0.987 to 1.134). No significant associations were found for haemorrhagic stroke. In two-pollutant models, the effects of O3remained significant after each of the other pollutants were included in the model, in particular with PM10. A significant association was observed for ischaemic strokes of large arteries (p = 0.02) and for transient ischaemic attacks (p = 0.01). Moreover, the authors found an exposure-response relations between O3exposure and ischaemic stroke (test for trend, p = 0.01). An increase in association in men with several cardiovascular risk factors (smoker, dyslipidemia and hypertension) was also observed.

Conclusion:These observational data argue for an association between ischaemic stroke occurrence and O3pollution levels; these results still need to be confirmed by other studies.
Long-term use of cellular phones and brain tumours: increased risk associated with use for ⩾10 years
Authors: Hardell Lennart , Carlberg Michael , Söderqvist Fredrik , Mild Kjell Hansson , Morgan L. Lloyd
Published: April 2007

Aim:To evaluate brain tumour risk among long-term users of cellular telephones.

Methods:Two cohort studies and 16 case–control studies on this topic were identified. Data were scrutinised for use of mobile phone for ⩾10 years and ipsilateral exposure if presented.

Results:The cohort study was of limited value due to methodological shortcomings in the study. Of the 16 case–control studies, 11 gave results for ⩾10 years’ use or latency period. Most of these results were based on low numbers. An association with acoustic neuroma was found in four studies in the group with at least 10 years’ use of a mobile phone. No risk was found in one study, but the tumour size was significantly larger among users. Six studies gave results for malignant brain tumours in that latency group. All gave increased odd ratios (OR), especially for ipsilateral exposure. In a meta-analysis, ipsilateral cell phone use for acoustic neuroma was OR = 2.4 (95% CI 1.1 to 5.3) and OR = 2.0, (1.2 to 3.4) for glioma using a tumour latency period of ⩾10 years.

Conclusions:Results from present studies on use of mobile phones for ⩾10 years give a consistent pattern of increased risk for acoustic neuroma and glioma. The risk is highest for ipsilateral exposure.
THE RELATIONSHIP BETWEEN LOAD TRANSMISSION AND DISC DEGENERATION IN THE THORACOLUMBAR SPINE: A FINITE ELEMENT STUDY
Authors: Zhou Yuan-Li , Qiu Tian-Xia , Zhang Qing-Hang , Teo Ee-Chon
Published: April 2007

Degenerative changes to the intervertebral disc structure appear gradually in the aging process, and are likely to affect the fracture patterns of the thoracolumbar vertebral body — a common site of spinal injuries — by changing the mechanical interaction within each motion segment. This study focused on the influence of disc degeneration on the mechanism of load transmission through the thoracolumbar vertebral body. Compressive stresses and ways of load transmission were examined in cases of normal and degenerated discs. The stress analysis was performed using the finite element (FE) method. For normal discs, the highest compressive stresses were found in the central region of the discs, corresponding to the anatomical nucleus. Such high stress made the endplates bulge towards the vertebral bodies. Hence, the fracture would most probably start in the center of the endplate. For degenerated discs, the peak stresses rose to high levels in the annuli. Thus, the annulus was mostly under compression, and so was the periphery of the endplate, with much less deflection at its center. The failure of the vertebra was due to the fracture of the periphery of the endplate. Ways of load transmission through the vertebral body were strongly affected by the disc condition.
ENCAPSULATION OF PERIOSTEAL STEM CELLS IN INJECTABLE PHOTOPOLYMERIZED HYDROGEL ENHANCES TENDON GRAFT OSTEOINTEGRATION
Authors: Liu Hsia-Wei , Chen Chih-Hwa , Tsai Ching-Lin , Yu Chung-Ming , Lin I-Hsuan , Hsiue Ging-Ho
Published: April 2007

Photopolymerized hydrogel based on poly(ethylene glycol) diacrylate (PEGDA) was applied to periosteum-derived periosteal stem cell (PSC) encapsulation and orthopedic tissue engineering. To provide support for cell adhesion, hyaluronic acid (HA) was incorporated into the PEGDA solution prior to photopolymerization. HA can be utilized to mimic the extracellular matrix composition as well as control cell growth and differentiation. In vitro studies have demonstrated its ability to encapsulate PSCs to form bone-like tissue in a photopolymerized hydrogel. Osteointegration of a tendon graft within the bone tunnel is a primary concern when employing tendon grafts for ligament reconstruction. This study presents a novel technique for fabricating injectable hydrogel–photoencapsulated PSCs in a bone tunnel to enhance tendon–bone healing. A total of 21 adult New Zealand white rabbits were used. The long extensor digitorum tendon was transplanted into a bone tunnel of the proximal tibia. The tendon was pulled through a drill hole in the proximal tibia and attached to the medial aspect of the tibia. Hydrogel suspension containing PSCs at a concentration of 20 million/mL was injected into the bone tunnel. Histological examination of the tendon–bone interface and biomechanical testing for maximal pull-out load were evaluated at postoperative weeks 3 and 6. Histological analysis of the tendon–bone interface showed an interface fibrous layer formed by the photoencapsulation of PSCs between the tendon and the bone. This layer became progressive integrated with the tendon–bone surface during the healing process. Biomechanical testing revealed higher maximal pull-out strength in experimental groups with a statistically significant difference at 3 and 6 weeks. These results suggest that photopolymerizable PEGDA and HA hydrogels are promising for tissue-engineered stem cell therapy to enhance tendon–bone healing.
DEGRADATION OF LOW-FREQUENCY NOISE IN AlGaN/GaN HEMTS DUE TO HOT-ELECTRON STRESSING
Authors: JHA SHRAWAN K. , ZHU CHANG-FEI , PILKUHN MANFRED H. , SURYA CHARLES , SCHWEIZER HEINZ
Published: April 2007

We report on the degradation of low-frequency excess noise in recessed gate AlGaN/GaN HEMTs due to hot-electron stressing. The I-V characteristics and the low-frequency noise power spectral densities, SV(f), of the open circuit voltage fluctuations across the drain source terminal were characterized with the stress time. Based on these results, we observed that the overall low-frequency noise degradation process can be identified to occur in two distinct phases. In the first phase, devices initially show fluctuations in the noise properties around a relatively constant average value. Detailed characterizations of the gate-source bias, VGS, dependence of SV(f) at cryogenic temperatures indicate signature-patterns in the variations of SV(f) as a function of VGS. This is shown to arise from the modulation of the percolation paths of the carriers in the two-dimensional electron gas (2DEG). The onset of the second phase of degradation arises from the irreversible generation of interface states at the AlGaN/GaN hetero-interface.
A PROBABILISTIC APPROACH TO MULTI-DOCUMENT SUMMARIZATION FOR GENERATING A TILED SUMMARY
Authors: SARAVANAN M. , RAMAN S. , RAVINDRAN B.
Published: April 2007

Data availability is not a major issue at present times in view of the widespread use of Internet; however, information and knowledge availability are the issues. Due to data overload and time-critical nature of information need, automatic summarization of documents plays a significant role in information retrieval and text data mining. This paper discusses the design of a multi-document summarizer that uses Katz's K-mixture model for term distribution. The model helps in ranking the sentences by a modified term weight assignment. Highly ranked sentences are selected for the final summary. The sentences that are repetitive in nature are eliminated, and a tiled summary is produced. Our method avoids redundancy and produces a readable (even browsable) summary, which we refer to as an event-specific tiled summary. The system has been evaluated against the frequently occurring sentences in the summaries generated by a set of human subjects. Our system outperforms other auto-summarizers at different extraction levels of summarization with respect to the ideal summary, and is close to the ideal summary at 40% extraction level.
DISTRIBUTED ADAPTIVE MULTIVARIATE FUNCTION VISUALIZATION
Authors: LI SHUJUN , KAUGARS KARLIS , DE DONCKER ELISE
Published: April 2007

In this article, we introduce a new function visualization method and demonstrate that numerical integration and visualization of multi-dimensional functions are closely related. Adaptive numerical integration is utilized to reduce the number of function evaluations, and generate time series data. The integration region is partitioned into a uniform grid. A grid cell can be sampled many times, or is not sampled at all, depending on the function properties and the integration rule. Function properties are extracted during the process of function evaluation. An aging technique helps visualize functions by retaining the most recently sampled areas and making the older ones transparent. This also results in giving the non-smooth areas more attention than the smooth areas. The new function visualization method gives a view of the whole function while elaborating on important areas such as ridges and troughs, which are critical in many fields, including numerical integration. A Grid service, called Integration Service, is used to solve computationally intensive integration problems. Remote visualization based on the adaptive method helps monitor the progress of a computation, and can be utilized for computational steering. The data are filtered by the server and transferred to the client, which is responsible for visualization mapping and rendering.
Slowing propagation error caused by finite register sizes in unstable systems
Authors: Cynar Sandra J.
Published: April 2007

When doing simulations one of the worst problems that can occur is an unstable system model. These unstable models often appear in systems identification problems where the system has a non-minimum phase model. This situation leads to an unstable inverse system. The instability means that the system model must be redefined, even though the non-minimum phase model is most accurate. Or a method for deconvolution will be chosen that assumes the system is minimum phase, even though it is not. Often these inaccurate fixes or assumptions are not necessary. Cases where short strings of data are being processed can use the unstable inverse and produce good results. By using the superposition feature of linear systems it is possible to increase the useful run time of these unstable deconvolvers.
How accurate should numerical routines be?
Authors: Dunham Charles B.
Published: April 2007

J. H. Wilkinson, in justifying backward error analyses, advanced the proposition that a numerical routine could not be blamed if the computed answer was the exact answer to the problem with slightly perturbed input. Such a model was established by Wilkinson (1968) for the solution of linear equations, ns by (I) Gaussian elimination and (II) triangular decomposition using double precision accumulation of inner products. In the latter it is usual that inputs are perturbed only by a small multiple of a unit rounding error (see formula (175)).
A note on comparison of nonlinear least squares algorithms
Authors: Khan Zafar , Chawla Sudhir , Dave Dinesh
Published: April 2007

The nonlinear least squares problem is a special case of the unconstrained minimization problem. While a large number of new algorithms have been developed in recent years, both for general unconstrained minimization and the least squares case, comparative studies are limited. Further, there has been practically a revolution in algorithm testing and comparison methodology. Recent advances include a more comprehensive performance criteria, use of large numbers of randomly generated test problems, and application of sophisticated statistical techniques for experiment design and data evaluation.These developments have made questionable the findings of the few earlier comparative studies of least squares algorithms. This creates a necessity of a comparative study employing current methodology that evaluates the specialized least squares algorithms along with a few general algorithms for unconstrained minimization.
Mazes in disguise
Authors: Goodman D.
Published: April 2007

Mazes are fun. Their appeal stems from their simplicity, their relevance to everyday problem solving, and their beauty. This article will give a simple algorithm by which interesting random mazes can be generated.
Automatic program development using PIA-CASE tool
Authors: Kokol P.
Published: April 2007

The PIA - CASE tool supports the PIA (Provisional Implementation Approach) which is a specific reduction of the Extended Operational Paradigm (EOP). EOP is based on the M
3
UO framework which takes into account Multidimensional, Multiview and Multilingual aspects of the information system development process and realizable ideas of operational prototyping and transformational paradigms. The PIA CASE tool is a continuation of the JSP Tutor and transforms the JSP operational specification expressed graphically by JSP structure diagrams and textually with newly developed Pointer-Less Array-Less Oriented Language (PLALOL) into spreadsheet and macros.
Sift - searching in free text
Authors: Reigem Oystein
Published: April 2007

The SIFT project is aimed at developing an advanced text retrieval system possessing the features of high modularity, high portability, possibilities for integration with word processing systems and a flexible user interface. Possible applications for such a system would be found wherever any sizable collection of information requires efficient retrieval. The SIFT system is mainly designed to solve the problems of searching in free, i.e. unstructured, text but extensive functions for dealing with structured information are also offered.The SIFT project is based on former experience in the use of other retrieval systems, particularly the Norwegian version of the British STATUS system, NOVA*STATUS, a system which has found application in various public agencies and at all Norwegian universities.The SIFT project was initiated on January 1, 1980, and a prototype version of the system will be implemented on a NORD computer towards the end of 1981. The final product will be made available free of charge.This presentation will treat the structure, characteristics and applications of the SIFT system.
Folk (abstract only)
Authors: Oldervoll Jan
Published: April 2007

Ethnography is a methodology which emphasises a "soft" interpretative approach to social reality. It is often portrayed as being at the opposite pole to quantitative approaches as exemplified in the classic Merton-Lazarsfeld paradigm (Structural-Functionalism wedded to the survey method).Ethnography is a method in which the researcher actively engages in and records the life of a social group. This record of experience is essentially qualitative. It is primarily constructed in the form of textual description: an ongoing account of a person's observations, thoughts and feelings while in the "field". This text is usually given the generic title of field-notes.The Ethnographic researcher is therefore normally confronted with a vast amount of textual data. To get some understanding of, and control over this data, the Ethnographer must in some way split up this record of raw experience. He must in some way "chunk" up his data into easily manageable units or categories. It is this classificatory activity which forms the basis of Ethnographic analysis.In greater detail, Ethnographic data analysis may be generally portrayed as consisting of three analytically distinct, but empirically indistinct activities: represents a1. The reading of field-notes, accompanied by the recording of themes and hypotheses;2. The coding of important topics observed within the field-notes under different category headings;3. The disassembling of field-notes by coded category; the purpose being the creative filing and retrieving of one's data.The prime concern of this presentation will be to discuss means by which such analysis may be accomplished.It is the author's belief that the schema shown below possible evolutionary trend in Ethnographic data analysis: items lower down the schema give the Ethnographer greater power and flexibility in the way he handles text. Reference will be made to presently ongoing research at Cardiff as evidence of this claim.1. The Traditional Filing Cabinet.a. Simple chronological filing of text.b. Multiple filing: the actual disassembling of text into files.2. The Filing cabinet and Separate Indices.a. Chronological filing: card indices.b. Chronological filing: specialised indices.c. Chronological filing: computer indices.3. The Full Computer Approach.a. Indices and fieldnotes stored on UNIX.b. A System of Personalised Interactive Computing for Ethnographers. SPICE: a term purely invented to emphasise the "spice" of Ethnographic research.Finally, this presentation will also discuss the implications that this research has for textual management in general. The projected computer arrangement will, I believe, prove of advantage not only to the Ethnographer, but to any researcher who employs continuous text as his/her primary resource.
New file management in P-STAT (abstract only)
Authors: Buhler Roald
Published: April 2007

In January of 1981, the Center for the Study of Youth Development initiated an on-line catalog of the holdings of its specialized library consisting of 10,000 monographs, journals, vertical file materials, etc. The present paper discusses the reactions of the end-user or patron population to the resource. The background of the library automation project -- including issues of cost-effectiveness, increased power, and user utility--is discussed in order to establish the initial goals of this activity. Then, attention is given to how the project was implemented; this includes a comparison of preliminary goals with what ultimately was delivered. The transition from a COM catalog to the on-line catalog required training of patrons (some of whom had little or no experience with a computer terminal), and only half of the Center staff participated in the initial training sessions. Preliminary patron behavior is reviewed, and an attempt to informally analyze both positive and negative experiences is offered. The initial experiences are summarized in a discussion of the problems and prospects of the user interface of the "query" portion of the on-line catalog software.
Operating systems, editors and application packages
Authors: Bezdek William
Published: April 2007

The purpose of this presentation is to describe an alternative sociology course that links student computer skills with available social survey data. Students are given access to a file of SPSS programs which they can easily modify to fit their own purposes. Using the General Social Survey they can test hypotheses on current data reflecting their interests. The broad range of data allows beginning students with little or no previous computer experience to investigate a wide variety of topics.
Recent advances in user assistance
Authors: Relles N. , Sondheimer N. K. , Ingargiola G. P.
Published: April 2007

As interactive users find conventional methods of training and documentation inadequate, designers are providing systems with online reference information, descriptions of valid input, elaboration of error messages, and explanations of a system's behavior. This paper describes some existing commercial systems that offer online assistance and more experimental approaches by the research community. The following material was originally presented at the SIGSOC conference on Easier and More Productive Use of Computing Systems. An extended version will appear in a special issue of the IEEE Transactions on Systems, Man, and Cybernetics (Volume SMC-12, March/April, 1982), and is reprinted here with the permission of the IEEE.Online user assistance is now offered on commercial systems and is the subject of investigation in experimental settings. It is difficult to compare the advantages and limitations of different approaches because they vary along many dimensions and because there is no commonly accepted terminology. A grouping of these dimensions into major categories is a necessary first step towards more empirical evaluations. The major software-related features of online assistance appear to fall into four categories:• access method -- the way users can construct or enter requests for assistance;• data structure -- the manner in which different portions of assistance information are related to each other;• software architecture -- how assistance requests and their responses are communicated among a user, an operating system, application programs, and the assistance database; and• contextual knowledge -- how much information is retained about the assistance environment, including the user, the application, and the tasks being performed.
Automatic construction of explanation networks for a cooperative user interface
Authors: Hayes Philip J. , Glasner Ingrid D.
Published: April 2007

This paper is concerned with providing
automatically generated
on-line explanations to the user of a functional computer subsystem or
tool
about what the tool can and cannot do, what parameters and options are available or required with a given command, etc.. The explanations are given through the COUSIN interface system which provides a cooperative tool-independent user interface for tools whose objects, operations, input syntax, display formats, etc. are declaratively represented in a
tool description
data base. The explanations are produced automatically from this data base, with no incremental effort on the part of the tool designer, and in a single uniform style for any tool that uses COUSIN as its interface. The explanation facility takes the form of a fine-grained, tightly linked network of text frames supported by the ZOG menu-selection system. Exactly what information the net building program, NB, extracts from a tool description, and the way in which this information is formatted in the text frames is controlled by a second declarative data base called the
aspect description
. The declarative nature of the aspect description makes it easy to adapt NB to changes in and extensions to the tool description formalism, and to experiment with the structure of the explanation network. We also describe how the appropriate network frame can be found and displayed in response to specific explanation requests from the user.
Evaluating the “friendliness” of a timesharing system
Authors: Borman Lorraine , Karr Rosemary
Published: April 2007

The decade of the Sixties served to introduce most university campuses to the computer; the Seventies brought the computer, via a terminal, into every facet of university life. Computing in the Eighties will cause every university and college to evaluate and reconsider its exploitation of modern computing equipment for education and research.For example, at Northwestern University, it was recognized that continued growth in timesharing would be a major factor in computing at NU in the 1980s and that this growth would come from a large community of new users and of casual users. In January 1980, the Computing Center began a long-range planning study. A five-year equipment enhancement and replacement plan was to be developed which was intended to reverse an unsatisfactory trend toward computer saturation, to further improve and modernize our computer offerings, and to ensure that NU remained on a path of excellence in computing. Since time-sharing had already increased to over 50% of the total usage of the computer, a decision was made to begin the evaluation of modern timesharing systems, with special emphasis in two areas: 1) efficiency and reliability, and 2) the user interface.This paper describes the processes which were developed and used for the evaluation of the user interface, or as it came to be known, the "friendliness" study [1].
A study of procedure descriptions by non-programmers (abstract only)
Authors: Miller Lawrence
Published: April 2007

Providing mechanisms for inexperienced users of computer systems to program the computer to repetitively perform tasks that the user normally does in his or her daily job is one of the most challenging tasks for designers of highly interactive computer systems oriented to naive users. This report presents early results of a study conducted to ascertain the written analogues of the programming structures
iteration, conditional
and
variables
. The study required users already familiar with office procedures to practice a routine forms fill-in and data verification task over a period of one week. At the end of that time, they were required to
write
a set of procedures as if they were instructing a new person in the performance of the job. These written protocols (in conjunction with verbal protocols taken during the learning phase) were analyzed in terms of the above-mentioned structures.It was found that a variety of structures are used by naive users, but more importantly, all users made serious errors of both omission and commission. In particular, events of low probability were not described at all. In certain cases the written instructions did not correspond with the way in which users actually performed the tasks.The implications for office systems designers, amongst others, are explored.
Learning effectiveness
Authors: Weinberg Sherry
Published: April 2007

Response time is one of the key components of the human interface in an interactive computer system. This study evaluated two different response times and their impact on learning effectiveness. Using a counterbalanced experimental design (2**2 combinations of 2 response times), this study measured completion times, lesson mastery, error rates, and attitude. Data were obtained from student questionnaires.The Control Data PLATO Computer-based Education system provided the environment for the study. The system was connected to two networks with different response time characteristics. The means of the two response times tested were .25 sec (response time A) and 1.3 seconds (response time B). The covariate analysis of variance and chi square tests were used to show the significant difference between the two response times (p < .05), giving the following results:1. The subjects using the shorter response time finished the lessons significantly faster than the subjects using the longer response time.2. The number of subjects that mastered the lessons was significantly higher for the subjects using the shorter response time.3. The performance of subjects using the shorter response time for time dependent tasks was significantly better than the subjects using the longer response time. However, for time independent tasks, the subjects using the longer response time performed significantly better.4. The subjects using the faster response time showed significantly more favorable attitudes toward the response time experienced than the subjects using the slower response time.In conclusion, the shorter response time (A) was more efficient for learning and was more favored by students.