bluuebunny/crossref_metadata_2025 huggingface dataset:
Id1 restrains myeloid commitment, maintaining the self-renewal capacity of hematopoietic stem cells
Authors: Jankovic Vladimir , Ciarrocchi Alessia , Boccuni Piernicola , DeBlasio Tony , Benezra Robert , Nimer Stephen D.
Published: January 2007

Appropriate hematopoietic stem cell (HSC) self-renewal reflects the tight regulation of cell cycle entry and lineage commitment. Here, we show that Id1, a dominant-negative regulator of E protein transcription factors, maintains HSC self-renewal by preserving the undifferentiated state. Id1-deficient HSCs show increased cell cycling, by BrdU incorporation
in vivo
, but fail to efficiently self-renew, leading to low steady-state HSC numbers and premature exhaustion in serial bone marrow transplant assays. The increased cycling reflects the perturbed differentiation process, because Id1 null HSCs more readily commit to myeloid differentiation, with inappropriate expression of myeloerythroid-specific genes. Thus, Id1 appears to regulate the fate of HSCs by acting as a true inhibitor of differentiation.
Structural analysis and dimerization potential of the human TAF5 subunit of TFIID
Authors: Bhattacharya Suparna , Takada Shinako , Jacobson Raymond H.
Published: January 2007

TFIID is an essential factor required for RNA polymerase II transcription but remains poorly understood because of its intrinsic complexity. Human TAF5, a 100-kDa subunit of general transcription factor TFIID, is an essential gene and plays a critical role in assembling the 1.2 MDa TFIID complex. We report here a structural analysis of the TAF5 protein. Our structure at 2.2-Å resolution of the TAF5-NTD2 domain reveals an α-helical domain with distant structural similarity to RNA polymerase II CTD interacting factors. The TAF5-NTD2 domain contains several conserved clefts likely to be critical for TFIID complex assembly. Our biochemical analysis of the human TAF5 protein demonstrates the ability of the N-terminal half of the TAF5 gene to form a flexible, extended dimer, a key property required for the assembly of the TFIID complex.
Regulation of IL-27 p28 gene expression in macrophages through MyD88- and interferon-γ–mediated pathways
Authors: Liu Jianguo , Guan Xiuqin , Ma Xiaojing
Published: January 2007

Interleukin (IL)-27 is the newest member of the IL-12 family of heterodimeric cytokines composed of the Epstein-Barr virus–induced gene 3 and p28 chains. IL-27 not only plays an important role in the regulation of differentiation of naive T helper cells but also possesses antiinflammatory properties. IL-27 is an early product of activated monocytes/macrophages and dendritic cells. However, the mechanisms whereby inflammatory signals stimulate IL-27 production have not been explored. In this study, we investigated the transcriptional regulation of the mouse IL-27 p28 gene in macrophages in response to lipopolysaccharide (LPS) and interferon (IFN)-γ. We found that LPS-stimulated p28 production was completely dependent on the Toll-like receptor 4/myeloid differentiation factor 88 (MyD88)–mediated pathway but only partially dependent on nuclear factor κB c-Rel. IFN-γ–induced p28 production/secretion was also partially dependent on MyD88 but independent of c-Rel. We then cloned the mouse p28 gene promoter and mapped its multiple transcription initiation sites. Furthermore, we identified critical promoter elements that mediate the inductive effects of LPS and IFN-γ, separately and synergistically, on p28 gene transcription in a c-Rel– and interferon regulatory factor 1–dependent manner, respectively.
Dielectric Relaxation in Nickel Fluorosilicate Hexahydrate
Authors: R Rommetveit  , I Svare
Published: January 2007

Dielectic properties of single crystals of Ni-, Fe-, and Zn-fluorosilicates have been studied from 100 to 270 K. In spite of the symmetry of the ions, NiSiF6· 6H2O shows sharp dielectric losses with activation energyEa= 6.8 kcal/mole. The loss frequencies are compared with SiF6-2reorientation motion and H2O flip motion determined by NMR. Fe- and Zn-fluorosilicates have no clear loss maxima.
Soft Gravitation Radiation
Authors: Christer Alvegård  , K-E Eriksson  , Christian Högfors
Published: January 2007

The methods of soft photon radiation are applied to the linearized theory of gravitation in a radiation gauge similar to the radiation gauge in quantum electrodynamics. The time evolution of soft graviton emission following any scattering process is studied in detail. Results obtained by Weinberg in a different way are reproduced.
The Physics of QSO Absorption Line Regions
Authors: A Boksenberg
Published: January 2007

The physical properties of the absorption systems observed in high redshift QSOs are described in some detail. Apart from the very broad absorption lines seen in a few objects, which almost certainly are due to intrinsic mass outflow, the great majority of the narrow absorption lines commonly present in QSO spectra, ranging in relative velocity from a large fraction of c outward to a few thousand km s-1 inward, all of which are characteristically similar and resemble interstellar lines, can be most naturally explained as being produced in cosmologically distributed intervening material consisting of both enriched and primordial gas.
The Line-locking Hypothesis, Absorption by Intervening Galaxies, and the z = 1.95 Peak in Redshifts
Authors: G Burbidge
Published: January 2007

Arguments concerning the line-locking hypothesis and the intervening galaxy hypothesis are briefly discussed. A detailed discussion of the 1.95 peak in emission and absorption redshifts is given.
The Nature of the Nebulosity Around BL LAC Objects
Authors: James E Gunn
Published: January 2007

Without abstract, see full text
Self Consistent Models for the Emissive Regions of Quasars and Seyfert Nuclei
Authors: S Collin-Souffrin
Published: January 2007

Models for the region emitting the forbidden and the permitted lines of Quasars and Seyfert nuclei are reviewed. First, the mode of energy supply is discussed, and it is concluded that, while the supply is predominantly radiative in the region emitting the forbidden lines, as generally assumed, it is probably partly kinetic in the region emitting the permitted lines.

The models include stationary photoionized models, where the thermal equilibrium and the transfer are solved, models in which the transfer and the thermal equilibrium are not taken into account, and time dependent photoionized models. A brief discussion of the other kinds of possible models is given.
On the Periodicity in the Distribution of Quasar Redshifts
Authors: Per Kjærgaard
Published: January 2007

The periodicity in the distribution of quasar redshifts, previously found by Karlsson [1] and recently discussed by Karlsson [2] and Barnothy and Barnothy [3], is explained in terms of selection effects. Special attention is drawn to a selection effect caused by the redshift dependent influence of the strong emission lines on the limiting magnitude for detecting quasars. This is especially important since the number of quasars increases with a large factor per magnitude. The limiting magnitude effect applies both to spectroscopic and to UV-excess surveys.

It is shown that the redshift distribution of quasars selected by a combination of UV-excess information and agreement between radio and optical position is intermediate between the redshift distribution of the two groups of quasars selected by one of the two criteria. It is also shown that the distribution of redshifts for UV-excess selected quasars is very similar to the variation of the ultraviolet excess as a function of redshift. This evidence indicates that strong selection effects are in play.
Dissipative Processes, Galaxy Formation and "Early" Star Formation
Authors: Martin J Rees
Published: January 2007

Scenarios are described for the process whereby the primordial material is transformed from gas at z ≃ 1000 into bound systems and stars at the present epoch. The alleged "missing mass" could consist of stars which condensed at z ≳ 100 before galaxies had formed as gravitationally bound units.
Origin of X-Ray Emission from Clusters
Authors: Riccardo Giacconi
Published: January 2007

The results on the X-ray emission from clusters are reviewed. Correlations with morphological properties of the clusters are discussed. Recent findings on this topic, as well as on the possible detection of X-ray emission from superclusters, are high-lighted.
Nonlinear Interaction Involving Zero Energy Waves
Authors: D Anderson  , A Bondeson  , M Lisak  , R Nakach  , H Wilhelmsson
Published: January 2007

Three-wave interactions involving one or two modes with non-definite sign of wave energy, treated by second order differential equations in time, are studied. The third mode is assumed to suffer heavy linear damping, and is treated by means of Tang's adiabatic approximation. The possibility of negative pump energy and positive decay mode energy is shown to lead to an explosive situation. Self-similar explosive solutions are derived, and it is shown that almost any solution asymptotically approaches, in some sense, these self-similar solutions.
Measurement of the Electron Double Ionization Cross Section of the K-shell in Cr and Fe
Authors: J Saijonmaa  , O Keski-Rahkonen
Published: January 2007

Kαh-hypersatellite (1s-2(1S0) → 1s-12p-1(3,1P1)) X-ray intensities relative to theKβ1,3lines are measured from thick anodes of Cr and Fe as a function of the incident electron energy. An integral equation for the electron double ionization cross section (EDC) of theK-shell is written for a thick target and solved for the EDC using semiempirical data of electron slowing-down in matter. A semiclassical calculation of the EDC, presented in the companion paper, yields values in good agreement with our experimental results.
Mössbauer Effect Studies of Taenite Lamellae of an Iron Meteorite Cape York (III. A)
Authors: J F Albertsen  , M Aydin  , J M Knudsen
Published: January 2007

Mössbauer spectra have been obtained for 12 taenite lamellae from the iron meteorite Cape York. The spectra show that generally the lamellae contain three phases. A paramagnetic γ-phase, a martensitic α2-phase and an ordered phase (superstructure) of the composition FeNi and with the structure L10. This superstructure has not previously been detected in meteorites. The ordered phase is concentrated in the outer layers of the lamellae. The outermost layer (1-2 μm) is practically pure superstructure. Mössbauer experiments show that the superstructure breaks down in about 10 hours at a temperature of 732 K. The formation of the ordered structure explains several general features of iron meteorites.
A Mechanical Model of the Charge-Monopole System
Authors: J M Leinaas
Published: January 2007

The motion of a spinning particle, whose spin is constrained to point towards a fixed point in space, is shown to be identical to that of a charged particle moving in a magnetic monopole field. Quantization of this mechanical system is straight forward. In contrast to the quantum description of the charge-monopole system, no singularities are present. Only when suppressing the cyclic spin coordinate, a singularity corresponding to the "Dirac string" of the magnetic monopole will arise.
Changes in the gene expression of adiponectin and glucose transporter 12 (GLUT12) in lactating and non‐lactating cows
Authors: KOMATSU Tokushi , ITOH Fumiaki , SAKUMOTO Ryosuke , HODATE Koichi , OBARA Yoshiaki , KUSHIBIKI Shiro
Published: January 2007

Glucose delivery and uptake by the mammary gland is a rate‐limiting step in milk synthesis. Insulin resistance is believed to increase throughout the body following the onset of lactation. To study glucose metabolism in peak‐, late‐, and non‐lactating cows we analyzed the expression of an adipokine, namely, adiponectin, decreased insulin resistance, leptin, and a novel insulin‐responsive glucose transporter (GLUT12) in the adipose tissue and mammary gland by using real‐time polymerase chain reaction. Our results demonstrated that the mRNA level of adiponectin in the adipose tissue was greater in non‐lactating cows than in peak‐lactating cows. In the adipose tissue, there were no significant differences in the abundance of GLUT12 mRNA between the peak‐, late‐, and non‐lactating cows. In contrast, in the mammary gland, the mRNA level of GLUT12 was greater in non‐lactating cows than in peak‐ and late‐lactating cows. In the adipose tissue, the mRNA level of leptin and peroxisome proliferator‐activated receptor gamma 2 (PPARγ2) was greater in non‐lactating cows than in peak‐lactating cows. The results of the present study suggest that in lactating cows adiponectin plays an important role in insulin resistance in the adipose tissue; in the mammary gland, GLUT12 expression is believed to be an important factor for insulin‐dependent glucose metabolism.
Experience in adverse events detection in an emergency department: Incidence and outcome of events
Authors: Hendrie James , Sammartino Luke , Silvapulle Mervyn J , Braitberg George
Published: January 2007

Objectives:  The study was performed to determine the incidence, outcome and preventability of adverse events (AE) in an ED.

Methods:  The Quality in Australian Health Care Study methodology, modified to the ED, was utilized. Case histories of patients presenting to a tertiary hospital ED were screened for events. Events detected were classified, using a 104‐item data collection instrument, entered on Excel and analysed statistically using MINITAB.

Results:  A total of 5345 patients presented during the study period. Three thousand three hundred and thirty‐two patients completed full evaluation and comprised the study population. One hundred and ninety‐four events were detected. Except where specified, events with management causation ≤ 3 were excluded. This excluded 24 events (12.4%) leaving 170 for analysis. Of patients suffering an event, 53.5% occurred prior ED attendance, 41.7% of AE occurred within the ED, and 4.7% had contributions from both. The overall event rate, detected by the screening process, was 5.1%, with an incident rate of 1.98% and AE rate of 3.12%. The ED AE rate was 1.0%. If only those with management causation = 1 are excluded, then the overall event rate was 5.52%, with an AE rate of 3.33%. Fifty‐five per cent of events were judged to be preventable (preventability score ≥ 3). Events resulting in death and disability were more likely to be preventable (P ≤ 0.04).

Conclusion:  In conclusion, the Quality in Australian Health Care Study methodology has been utilized to provide data on incidents and AE in an ED.
Multifaceted education initiative minimizes pethidine prescribing in the emergency department
Authors: Taylor Simone E , Braitberg George , Lugt Josephine
Published: January 2007

Background:  Pain management experts have recommended a diminished role for pethidine because of lack of superiority for any indication and greater potential for adverse effects compared with morphine.

Objectives:  To evaluate the impact of a multifaceted education initiative on prescribing patterns and to minimize pethidine use in the ED.

Methods:  This was a pre‐ and post‐intervention study. The intervention was an education initiative, introduced between December 2003 and January 2004. It comprised ED pharmacist in‐services for medical and nursing staff, championing by senior medical staff (ED consultants, surgical units, Drug and Therapeutics Committee) and concurrent prescriber feedback by ED pharmacists. The pre‐intervention prescribing practices guided the development of in‐services and the educational programme. The intervention was evaluated by a medical record review of analgesic prescribing in March–April of both 2003 (pre‐intervention period) and 2004 (post‐intervention period). Outcome measures were the proportions of patients who were prescribed pethidine and the proportions of pethidine ampoules supplied to the ED. Results were analysed as differences in proportions.

Results:  In the pre‐intervention period, 60 ampoules of pethidine (7.2% of opiate doses) and 777 ampoules of morphine (92.8% of opiate doses) were administered compared with 15 ampoules of pethidine (1.7%) and 869 ampoules of morphine (98.3%) in the post‐intervention period (P < 0.001). Of patients who received an opiate dose, 50 of 798 (6.3%) and 11 of 747 (1.5%) received pethidine in the pre‐ and post‐intervention periods, respectively (P < 0.001).

Conclusion:  Our education initiative resulted in a sustained and significant reduction in pethidine prescribing in the ED. Sustainability requires ongoing in‐services for ED staff, usually as part of the orientation programme.
Soil seed banks and plant community assembly following disturbance by fire and logging in interior Douglas-fir forests of south-central British Columbia
Authors: Stark Kaeli E. , Arsenault André , Bradfield Gary E.
Published: January 2007

Relationships between soil seed banks and aboveground understory vegetation were examined in dry Douglas-fir (Pseudotsuga menziesii (Beissn.) Franco) forests near Kamloops, British Columbia, to compare the effects of different disturbance types (low and high severity fires and non-salvage logging), and to evaluate how seed banks contribute to post-disturbance vegetation establishment. Sites were selected to represent disturbances at 1, 5, and 10 years prior to sampling, and data were analyzed using nonparametric univariate and multivariate statistical techniques. Seed density and species composition of seed banks did not differ significantly among the 1 year disturbed sites; however, the rooted frequencies of seed-origin plants in the establishing vegetation decreased in the order: lightly burned > severely burned > logged. Seed dispersal within the first year following fire is believed to be an important recovery mechanism on burned sites. Low frequencies of seed-derived plants, particularly conifer seedlings, on logged sites pose concerns for the initial recovery of vegetation following logging; nonetheless, the lack of significant differences in understory species composition between sites burned 5 years prior to sampling and sites logged 10 years prior to sampling, and their corresponding undisturbed sites, suggests that vegetation recovery can occur relatively quickly. Rooted frequencies of plants establishing naturally in burned areas were similar to those in undisturbed areas, which suggests that post-fire erosion control seeding using agronomic species may not be necessary in these forests.
Crown architecture development in Salix ‘Prairie Cascade’, a pendulous willow
Authors: Remphrey William R. , Pearn Linda P.
Published: January 2007

This paper presents a longitudinal quantitative architectural study of Salix ‘Prairie Cascade’, a hardy pendulous willow cultivar developed for the Canadian Prairies. Trees were propagated from cuttings in 1993 and detailed measurements were obtained on amount of extension growth, orientation of shoots with respect to gravity, and the fate of buds and shoots until 2000. Instead of the mixed axis model of Champagnat typically ascribed to weeping willows, upright main-stem axes were constructed by vigorous, mostly distal shoots that remained more or less upright. The pendulous habit was largely the result of lateral shoots that were initially upright or semi-pendulous, drooping under their own weight to become pendulous. The pendulous habit was exacerbated by the weight of foliage. Sylleptic shoots were frequently incorporated into the main-stem axes. From original 1993 shoots, 40% of the buds developed into sylleptic shoots compared with 29% that developed into proleptic shoots. Two orders of sylleptic branching were often produced in one year. Willow is known for branch shedding but only 7% of ‘Prairie Cascade’ shoots were shed in the first year; however, more than half were gone by the third year and most of those remaining were located on the upper half of parent shoots.
Field validation of an instantaneous estimate of in situ development and growth for marine copepod communities
Authors: Sastri Akash R , Dower John F
Published: January 2007

To date, efforts to develop a method for rapidly measuring the development and growth rates of marine zooplankton have met with little success. In recent years, however, a simple assay based on a crustacean moulting enzyme, chitobiase, has shown considerable promise. Previous laboratory studies have demonstrated that chitobiase activity is proportional to individual body size across three species of freshwater daphnids. Here, we show that a significant positive relationship exists between chitobiase activity and body length (and weight) across four species of marine copepods collected from natural populations in coastal British Columbia, Canada. We measured the decay rate of chitobiase in the water column and estimated in situ moulting and growth rates of the entire copepod community, which are in good agreement (5%–15%) with conventional moulting rates and literature-based estimates. This method can be applied at a relatively high spatial and temporal resolution and its utility is potentially analogous to conventional community-wide productivity estimates for phytoplankton and bacterioplankton in marine and freshwater systems.
Missing the target: uncertainties in achieving management goals in fisheries on Fraser River, British Columbia, sockeye salmon (Oncorhynchus nerka)
Authors: Holt Carrie A , Peterman Randall M
Published: January 2007

In sockeye salmon (Oncorhynchus nerka) fisheries, management targets are rarely achieved exactly, thereby creating uncertainties about outcomes from implementing fishing regulations. Although this type of uncertainty may be large, it is seldom incorporated into simulation models that evaluate management options. One objective of this study was to quantify the deviations that occur between realized and target mortality rates (i.e., the target fraction of adult recruits that die each year during return migration, mostly due to harvesting) in fisheries for sockeye salmon from the Fraser River, British Columbia. We found that for some sockeye stocks, realized mortality rates were higher than targets when recruitment was low (resulting in conservation concerns) and lower than targets when recruitment was high (resulting in foregone catch). Scientists and managers can at least partially account for effects of such deviations between realized and target mortality rates (outcome uncertainties) by choosing target harvest rules that reflect typical patterns in those deviations. We derived a method to permit modelers to incorporate those patterns into analyses of management options.
Implementation of the tangent modulus – vertical stress (Et–σv) model for flexible pavements analysis
Authors: Konrad J -M , Nguyen Ph D
Published: January 2007

A recently developed nonlinear elastic model of granular material, referred to as the tangent modulus – vertical stress (Et–σv) model, was implemented into a finite element numerical solver FlexPDE. The FlexPDE program was used to compare deflection predictions with actual plate-load test data from a site near Québec City. The proposed Et–σv model performed well and led to excellent predictions for load levels of 40, 50, and 70 kN. Comparison with predictions using the Uzan model suggests that constitutive models of granular materials are best expressed in terms of vertical stress rather than mean stress for the prediction of elastic pavement response for field conditions.Key words: granular material, resilient modulus, triaxial test, plate-loading test, finite element.
Damping-ratio measurements by the spectral-ratio method
Authors: Wang Yu-Hsing , Yan Wai Man , Lo Kai Fung
Published: January 2007

In this paper, bender elements are used as sensors to measure the damping ratio of soil by the spectral-ratio method. The results of numerical and physical experiments suggest that adequate measurement precision can be achieved by reducing the two types of inherent biases arising from (i) the near-field effect and (ii) the different transfer functions of the two receiver bender elements. The first bias can be avoided by setting sensors to r1/λ ≥ 2.0 and r1/r2≥ 2.0, where r1and r2are the distances between the source and the first and second receivers, respectively; and λ is the wavelength. The second bias can be minimized by modifying the original spectral-ratio method to accommodate the self-healing technique. The damping ratios, measured by this modified method, obtained from the experiment conducted in a tailor-made, true-triaxial apparatus are very similar to those obtained from resonant column tests under the same state of stress.Key words: bender element, damping ratio, spectral-ratio method, near-field effect, true-triaxial apparatus.
Using red mud bauxite for the neutralization of acid mine tailings: a column leaching test
Authors: Paradis M , Duchesne J , Lamontagne A , Isabel D
Published: January 2007

Acid mine drainage (AMD) is an environmental problem produced when sulphides come in contact with an oxidant (± bacteria) and water, producing acid generation and metals leaching. One solution proposed is to use red mud bauxite (RMB), which is very alkaline, to neutralize oxidized acidic tailings. A column leaching test has been set up to evaluate major aspects of field constraints. First, a field investigation was conducted in which RMB was spread in aggregates before mixing with tailings. This setup has been reproduced in the laboratory and compared with a homogeneous mixture. The analyses of the water effluent do not show any important difference between the two mixtures. Second, some studies show that the addition of Cl brine to RMB helps to maintain the long-term neutralization potential. Brine addition increased the concentrations of Ca, Mg, Na, K, and Cu in drainage water. Columns were set up with 10% and 20% RMB to evaluate the effect of the quantity applied. Addition of greater than 20% RMB increases the leachate alkalinity and concentrations of Al, Cu, Pb, As, Fe, and SO42– in drainage waters. The addition of 10% RMB, however, significantly improves the quality of drainage water over a period of 125 days and results in concentrations and pH values within the ranges of those recommended by Directive 019 of the Ministère de l'environnement, Québec.Key words: acid mine drainage, red mud bauxite, tailings, environmental geochemistry, neutralization.
FOCUSING OF OPINIONS IN THE DEFFUANT MODEL: FIRST IMPRESSION COUNTS
Authors: JACOBMEIER DIRK
Published: January 2007

This paper treats the opinion dynamics of an unequal, initial opinion distribution. We simulate the Deffuant model on a directed Barabási–Albert network with discrete opinions and several subjects. We notice a focusing of the the resulting opinion distribution during the simulation towards the average value of the initial opinion distribution. A small change of the focusing is seen. A dependency of this change on the number of subjects and opinions is detected and indicates the change as a consequence of discretization of the opinions. Hereby the average value of the initial opinion distribution can be identified as the guide of opinion forming.
DYNAMIC PHASE TRANSITION IN THE KINETIC BLUME-EMERY-GRIFFITHS MODEL IN AN OSCILLATING EXTERNAL FIELD
Authors: CANKO OSMAN , TEMİZER ÜMİT , KESKİN MUSTAFA
Published: January 2007

The dynamic phase transitions are studied, within a mean-field approach, in the kinetic Blume-Emery-Grifftihs model under the presence of a time varying (sinusoidal) magnetic field by using the Glauber-type stochastic dynamics and the set of the dynamic equations of motion is obtained. The behavior of the time-dependence of the order parameters and the behavior of the average order parameters in a period, which is also called the dynamic order parameters, as a function of the reduced temperature are investigated. The nature (continuous and discontinuous) of transition is characterized by studying the average order parameters in a period. The dynamic phase transition points are obtained and the phase diagrams are presented in the reduced magnetic field amplitude and reduced temperature plane. We have found that the behavior of system strongly depends on the interaction parameters and nine main different phase diagram topologies have been obtained. We also calculate the Liapunov exponents to verify the stability of the solutions and the dynamic phase transition points.
SYMMETRY AND SUPERSYMMETRY OF A NEUTRON IN THE MAGNETIC FIELD OF A LINEAR CURRENT
Authors: MARTÍNEZ D. , MOTA R. D. , GRANADOS V. D.
Published: January 2007

We study a neutron in an external magnetic field in coordinate space and show that the 2 × 2 radial matrix operators that factorize the Hamiltonian are contained within the constants of motion of the problem. Also we show that the 2 × 2 partners Hamiltonians satisfy the shape invariance condition.
CANONICAL TRANSFORMATION APPROACH TO THE CLASSICAL SOLUTION OF RLC COUPLED TWO-DIMENSIONAL CIRCUIT WITH AN ARBITRARY POWER SOURCE
Authors: CHOI J. R. , NAHM I. H.
Published: January 2007

The classical equations of motion for the dissipative RLC coupled two-dimensional circuit with a power source are solved using two-step canonical transformation. We applied our investigation to the system whose power source is the form of sinusoidally oscillating with time.
INTERPIXEL-SHIFTED ENDOSCOPIC OPTICAL COHERENCE TOMOGRAPHY FOR IN VIVO BLADDER CANCER DIAGNOSIS
Authors: WANG ZHENGUO , LEE CHRISTOPHER S. D. , WALTZER WAYNE C. , YUAN ZHIJIA , PAN YINGTIAN
Published: January 2007

An interpixel-shifted spectral imaging technique is applied to MEMS-based spectral-domain endoscopic optical coherence tomography (SDEOCT) to enhance signal-to-noise ratio and effective imaging depth for in vivo imaging diagnosis of biological tissue. To validate the enhancements of pixel-shifted SDEOCT, experimental comparisons are presented to image animal and human bladder architectures in vivo and to diagnose human transitional cell cancers. Preliminary study shows that interpixel shifted SDEOCT not only increases the depth of field of SDOCT but also eliminates excessive artifacts induced by spectral aliasing effect, thus improving image contrast in areas with large depths (e.g. over 1.5 mm). These results suggest that endoscopic OCT equipped with interpixel-shifted spectral camera has the potential to enhance the diagnosis of biological tissue in in vivo settings that require a larger field of view in the axial direction, such as papillary bladder tumors with deep surface irregularities (e.g. asperities or invaginations).
Minority report in fraud detection
Authors: Phua Clifton , Alahakoon Damminda , Lee Vincent
Published: January 2007

This paper proposes an innovative fraud detection method, built upon existing fraud detection research and
Minority Report
, to deal with the data mining problem of skewed data distributions. This method uses backpropagation (BP), together with naive Bayesian (NB) and C4.5 algorithms, on data partitions derived from minority oversampling with replacement. Its originality lies in the use of a single meta-classifier (stacking) to choose the best base classifiers, and then combine these base classifiers' predictions (bagging) to improve cost savings (stacking-bagging). Results from a publicly available automobile insurance fraud detection data set demonstrate that stacking-bagging performs slightly better than the best performing bagged algorithm, C4.5, and its best classifier, C4.5 (2), in terms of cost savings. Stacking-bagging also outperforms the common technique used in industry (BP without both sampling and partitioning). Subsequently, this paper compares the new fraud detection method (meta-learning approach) against C4.5 trained using undersampling, oversampling, and SMOTEing without partitioning (sampling approach). Results show that, given a fixed decision threshold and cost matrix, the partitioning and multiple algorithms approach achieves marginally higher cost savings than varying the entire training data set with different class distributions. The most interesting find is confirming that the combination of classifiers to produce the best cost savings has its contributions from all three algorithms.
Extreme re-balancing for SVMs
Authors: Raskutti Bhavani , Kowalczyk Adam
Published: January 2007

There are many practical applications where learning from single class examples is either, the only possible solution, or has a distinct performance advantage. The first case occurs when obtaining examples of a second class is difficult, e.g., classifying sites of "interest" based on web accesses. The second situation is exemplified by the gene knock-out experiments for understanding Aryl Hydrocarbon Receptor signalling pathway that provided the data for the second task of the KDD 2002 Cup, where minority one-class SVMs significantly outperform models learnt using examples from both classes.This paper explores the limits of supervised learning of a two class discrimination from data with heavily unbalanced class proportions. We focus on the case of supervised learning with support vector machines. We consider the impact of both sampling and weighting imbalance compensation techniques and then extend the balancing to extreme situations when one of the classes is ignored completely and the learning is accomplished using examples from a single class.Our investigation with the data for KDD 2002 Cup as well as text benchmarks such as Reuters Newswire shows that there is a consistent pattern of performance differences between one and two-class learning for all SVMs investigated, and these patterns persist even with aggressive dimensionality reduction through automated feature selection. Using insight gained from the above analysis, we generate synthetic data showing similar pattern of performance.
Feature selection for text categorization on imbalanced data
Authors: Zheng Zhaohui , Wu Xiaoyun , Srihari Rohini
Published: January 2007

A number of feature selection metrics have been explored in text categorization, among which information gain (IG), chi-square (CHI), correlation coefficient (CC) and odds ratios (OR) are considered most effective. CC and OR are one-sided metrics while IG and CHI are two-sided. Feature selection using one-sided metrics selects the features most indicative of membership only, while feature selection using two-sided metrics implicitly combines the features most indicative of membership (e.g. positive features) and non-membership (e.g. negative features) by ignoring the signs of features. The former never consider the negative features, which are quite valuable, while the latter cannot ensure the optimal combination of the two kinds of features especially on imbalanced data. In this work, we investigate the usefulness of explicit control of that combination within a proposed feature selection framework. Using multinomial naïve Bayes and regularized logistic regression as classifiers, our experiments show both great potential and actual merits of explicitly combining positive and negative features in a nearly optimal fashion according to the imbalanced data.
Performance evaluation for multiprocessors programmed using monitors
Authors: Lucier B. J.
Published: January 2007

We present a classification of synchronization delays inherent in multiprocessor systems programmed using the monitor paradigm. This characterization is useful in relating performance of such systems to algorithmic parameters in subproblems such as domain decomposition. We apply this approach to a parallel, adaptive grid code for solving the equations of one-dimensional gas dynamics implemented on shared memory multiprocessors such as the Encore Multimax.
The limited performance benefits of migrating active processes for load sharing
Authors: Eager D. L. , Lazowska E. D. , Zahorjan J.
Published: January 2007

Load sharing
in a distributed system is the process of transparently sharing workload among the nodes in the system to achieve improved performance. In
non-migratory
load sharing, jobs may not be transferred once they have commenced execution. In load sharing with
migration
, on the other hand, jobs in execution may be interrupted, moved to other nodes, and then resumed.

In this paper we examine the performance benefits offered by migratory load sharing beyond those offered by non-migratory load sharing. We show that while migratory load sharing can offer modest performance benefits under some fairly extreme conditions, there are
no
conditions under which migration yields
major
performance benefits.
A mean-value performance analysis of a new multiprocessor architecture
Authors: Leutenegger S. T. , Vernon M. K.
Published: January 2007

This paper presents a preliminary performance analysis of a new large-scale multiprocessor: the
Wisconsin Multicube
. A key characteristic of the machine is that it is based on shared buses and a snooping cache coherence protocol. The organization of the shared buses and shared memory is unique and non-hierarchical. The two-dimensional version of the architecture is envisioned as scaling to 1024 processors.

We develop an approximate mean-value analysis of bus interference for the proposed cache coherence protocol. The model includes FCFS scheduling at the bus queues with deterministic bus access times, and asynchronous memory write-backs and invalidation requests.

We use our model to investigate the feasibility of the multiprocessor, and to study some initial system design issues. Our results indicate that a 1024-processor system can operate at 75 - 95% of its peak processing power, if the mean time between cache misses is larger than 1000 bus cycles (i.e. 50 microseconds for 20 MHz buses; 25 microseconds for 40 MHz buses). This miss rate is not unreasonable for the cache sizes specified in the design, which are comparable to main memory sizes in existing multiprocessors. We also present results which address the issues of optimal cache block size, optimal size of the two-dimensional Multicube, the effect of broadcast invalidations on system performance, and the viability of several hardware techniques for reducing the latency for remote memory requests.
Design of partially replicated distributed database systems: an integrated methodology
Authors: Mukkamala R. , Bruell S. C. , Shultz R. K.
Published: January 2007

The objective of this research is to develop and integrate tools for the design of partially replicated distributed database systems. Many existing tools are inappropriate for designing large-scale distributed databases due to their large computational requirements. Our goal is to develop tools that solve the design problems reasonably quickly, typically by using heuristic algorithms that provide approximate or near-optimal solutions.

In developing this design methodology, we assume that information regarding the types of user requests and their rates of arrival into the system is known
a priori
. The methodology assumes a general model for transaction execution. In this paper we discuss three aspects of the design methodology: the data allocation problem, the use of a static load-balancing scheme in coordination with the allocation scheme, and the design evaluation and review step. Our methodology employs iterative design techniques using performance evaluation as a means to iterate.
The use of microcode instrumentation for development, debugging and tuning of operating system kernels
Authors: Melvin S. W. , Patt Y. N.
Published: January 2007

We have developed a tool based on microcode modifications to a VAX 8600 which allows a wide variety of operating system measurements to be taken with minimal perturbation and without the need to modify any operating system software. A trace of interrupts, exceptions, system calls and context switches is generated as a side-effect to normal execution. In this paper we describe the tool we have developed and present some results we have gathered under both UNIX 4.3 BSD and VAX/VMS V4.5. We compare the process fork behavior of two different command shells under UNIX, look at context switch rates for interactive and batch workloads and generate a histogram for network interrupt service time.
A model of performance for virtual memory systems
Authors: Brandwain A. , Buzen J. , Gelenbe E. , Potier D.
Published: January 2007

Queueing network models are well suited for analyzing certain resource allocation problems associated with operating system design. An example of such a problem is the selection of the level of multiprogramming in virtual memory systems. If the number of programs actively competing for main memory is allowed to reach too high a value, trashing will occur and performance will be seriously degraded. On the other hand, performance may also suffer if the level of multiprogramming drops too low since system resources can become seriously under utilized in this case. Thus it is important for virtual memory systems to maintain optimal or near optimal levels of multiprogramming at all times.

This paper presents an analytic model of computer system behavior which can be used to study multiprogramming optimization in virtual memory systems. The model, which explicitly represents the numerous interactions which occur as the level of multiprogramming varies, is used to numerically generate performance curves for representative sets of parameters. A simplified model consisting of a CPU and a single backing store device is then used to derive an approximate expression for the optimal level of multiprogramming. The simplified model is also used to examine the transient behavior of such systems.

The mathematical model we present is based on some simplifying assumptions; in particular all programs executing in the system are supposed to be statistically identical. In this respect the model we present must be considered to be a theoretical explanation of a phenomenon (thrashing) observed in certain operating systems rather than an exact representation of reality. Certain assumptions of the mathematical model are relaxed in a simulation model where distribution functions of service times at the secondary memory and input-output devices are arbitrary; by comparison with the theoretical results we see that CPU utilization and throughput are not very sensitive to the specific forms of these distributions and that the usual exponential assumptions yield quite satisfactory results. The simulation model is also programmed to contain overhead. Again we observe that the mathematical model's predictions are in fair agreement with the useful CPU utilization predicted by the simulation experiments.
The optimal choice of window sizes for working set dispatching
Authors: Henderson Greg , Rodriguez-Rosell Juan
Published: January 2007

The concept of varying window size in a working set dispatcher to control working set size and number of page faults is examined. A space-time cost equation is developed and used to compare fixed window size to variable window size for different types of secondary storage based on the simulated execution of real programs. A general approach is indicated for studying the relative merit of the two dispatching algorithms and their interaction with different hardware configurations.
Error modelling applications in software quality assurance
Authors: Sukert Alan N. , Goel Amrit L.
Published: January 2007

This paper presents the results of a two-phased experiment conducted by Rome Air Development Center and Syracuse University to demonstrate the potential applicability of software error prediction models in performing formalized qualification testing of a software package. First, decisions based upon the predictions of three software error prediction models will be compared with actual program decisions for a large command and control software development project. Classical and Bayesian demonstration tests are used to make accept/reject decisions about the software system. Finally, the results of the two phases will be compared and some conclusions drawn as to the potential use of these predictive techniques to software quality assurance.
Design feedback and its use in software design aid systems
Authors: Stavely Allan M.
Published: January 2007

It is argued that software system designers would benefit greatly from feedback about the consequences of a proposed design if this feedback could be obtained early in the development process. A taxonomy of possible types of feedback and other design aids is presented, and the capabilities of several existing design aid systems are described relative to this taxonomy.
The automatic generation and execution of function test plans for electronic switching systems
Authors: Bauer Jonathan , Faasse Susan , Finger Alan , Goodhue William
Published: January 2007

A three phase functional testing methodology is described for use in the development cycle of electronic switching systems. The methodology centers on a directed graph model of the system and provides for the checking of system requirements, the generation of functional tests and the automatic execution of these tests.
A simulation environment for performing dataflow research
Authors: Landry Steve P. , Shriver Bruce D.
Published: January 2007

Dataflow languages and processors are currently being extensively studied because of their respective ability to specify and execute programs which exhibit a high degree of parallel and/or asynchronous activity [12, 7]. This paper describes a comprehensive simulation environment that allows for the execution and monitoring of dataflow programs. One overall objective of this facility was to meet the needs of researchers in such diverse areas as computer architecture, algorithm analysis, and language design and implementation. Another objective was to accommodate the semantics of several of the contending abstract dataflow models [2, 4]. Additionally, it was desired to enhance the abstract dataflow models which the simulator would support. These objectives, combined with the desired debugging and metering requirements, directed the design of the overall system. A brief introduction to dataflow and its related terminology is given to assist the reader. A companion paper [6] describes an augmentation to the basic simulation facility presented here that allows for the execution of dataflow programs on processors having finite resources.
The impact of certain parameter estimation errors in queueing network models
Authors: Gordon Karen D. , Dowdy Lawrence W.
Published: January 2007

The effect that parameter estimation errors have on performance in closed product form queueing networks is investigated. In particular, the effects of errors in the relative utilization estimates of the servers are analyzed. It is shown that in single class load independent networks, the resulting errors in throughput and utilizations are of approximately the same percentage as the errors in the relative utilization estimates. This result does not hold in networks with load dependent servers or multiple customer classes. The percentage errors in mean queue length depend upon the degree of multiprogramming in the network. Errors in mean queue lengths can become unbounded as the degree of multiprogramming becomes unbounded.

Implications of these results to computer system modeling are discussed.
DIAMOND a digital analyzer and monitoring device
Authors: Hughes James H.
Published: January 2007

This paper describes the design and application of a special purpose computer system. It was developed as an internal tool by a computer manufacturer, and has been used in solving a variety of measurement problems encountered in computer performance evaluation.
Performance evaluation and prediction of storage hierarchies
Authors: Lehmann Axel
Published: January 2007

This paper proposes a modelling methodology combining simulation and analysis for computer performance evaluation and prediction. The methodology is based on a special workload model that is suitable for the generation and description of dynamic program behaviour. A description of this workload model is given in section 2. The applicability of this concept with respect to the design of new storage systems, as well as the improvement or comparison of existing systems, will be described by investigation of the efficiency of small cache memories in section 3.