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Number processing in temporal lobe epilepsy

M Delazer — 2008-01-28T09:26:25-00:00

J Neurol Neurosurg Psychiatry, Vol. 75, No. 6. (1 June 2004), pp. 901-903.

Background: Specific cognitive impairments have been found in association with mesial temporal lobe epilepsy (TLE), such as deficits in declarative memory or verbal abilities. No attention has been paid so far to possible deficits in number processing. Objective: To investigate deficits in number processing in patients with TLE. Methods: Numerical abilities were assessed in 28 right handed patients with medically intractable unilateral TLE and in a control group. Results: No differences between patients and controls were found in analogue number processing with Arabic input, in a comparison task, or in simple addition and simple subtraction; however, there were significant group differences in tasks with verbal input, in simple division, in complex mental calculation, in a semantic knowledge task, and in conceptual tasks. Only minor differences were found between patients with right and left TLE. Conclusions: While numerical deficits may be expected in patients with left sided TLE, it is open for discussion why patients with right sided TLE also show numerical deficits. 10.1136/jnnp.2003.023614

Explicit versus Implicit Processing of Representational Space in Neglect: Dissociations in Accessing the Mental Number Line

Konstantinos Priftis — 2007-12-16T18:28:58-00:00

J. Cogn. Neurosci., Vol. 18, No. 4. (1 April 2006), pp. 680-688.

The present study investigated the effects of left hemispatial neglect on two tasks activating the mental number line (MNL). Six patients with left neglect performed a mental number bisection task and a modified version of the Spatial Numerical Association of Response Codes (SNARC) task. Effects of left neglect were observed in the number bisection task, but not in the SNARC task. We argue that the dissociation between number bisection and SNARC resembles, in the representational space of the MNL, previously reported dissociations on neglect between explicit knowledge (assessed by direct tasks) and implicit knowledge (assessed by indirect tasks).

Software Product Lines: Research Issues in Engineering and Management

Timo Käkölä — 2008-04-24T12:56:58-00:00

(05 October 2006)

The software product line strategy has enabled many organizations to improve productivity, reduce time-to-market, and address both mass- and niche markets. A successful product line organization achieves strategic levels of architectural reuse. The topics in this book cover research related to the most important practices in a product line organization. The contributions provide experience-based knowledge about the domain and application engineering, the modeling and management of variability, and the design and use of tools to support the management of product line related knowledge. Käkölä and Dueñas have grouped them into five parts corresponding to the main areas of software product line engineering: product line management, product line requirements engineering, product line architecture, product line testing, and specific product line engineering issues. They ensured maximum coherence and cross-referencing throughout the book, imposing a common terminology and carefully integrating all chapters. The result is a valuable and enduring resource for researchers in both industry and academia who will also find many pointers for future research and implementation strategies. In addition, systems and software professionals, and technology managers aspiring to fully leverage the product line strategy will also benefit from many pertinent development details. "This volume is a valuable resource for researchers wishing to move the product line strategy forward and for those charged with translating state-of-the-art ideas into state-of-the-practice processes and activities." From the Foreword by John D. McGregor, Clemson University, USA

Software-Produktlinien

Georg Weindl — 2006-04-12T22:03:48-00:00

(30 June 2004)

Anforderungsbasierte Ableitung von Systemtestfall-Szenarien in der Software-Produktlinien-Entwicklung

Andreas Reuys — 2008-04-24T11:53:37-00:00

Aspectual Feature Modules

Sven Apel — 2008-04-03T13:48:23-00:00

Software Engineering, IEEE Transactions on, Vol. 34, No. 2. (2008), pp. 162-180.

Two programming paradigms are gaining attention in the overlapping fields of software product lines (SPLs) and incremental software development (ISD). Feature-oriented programming (FOP) aims at large-scale compositional programming and feature modularity in SPLs using ISD. Aspect-oriented programming (AOP) focuses on the modularization of crosscutting concerns in complex software. While feature modules, the main abstraction mechanisms of FOP, perform well in implementing large-scale software building blocks, they are incapable of modularizing certain kinds of crosscutting concerns. This weakness is exactly the strength of aspects, the main abstraction mechanisms of AOP. In this article we contribute a systematic evaluation and comparison of FOP and AOP. It reveals that aspects and feature modules are complementary techniques. Consequently, we propose the symbiosis of FOP and AOP and aspectual feature modules (AFMs), a programming technique that integrates feature modules and aspects. We provide a set of tools that support implementing AFMs on top of Java and C++. We apply AFMs to a non-trivial case study demonstrating their practical applicability and to justify our design choices.

Software product line migration and deployment

D Faust — 2007-08-31T12:38:40-00:00

Software: Practice and Experience, Vol. 33, No. 10. (2003), pp. 933-955.

We describe a method to migrate multiple instances of a successful single information system to a product line. The deployed product line is able to deal with the variants evolved over time in a cost-effective manner. We proposed and used federated architectures that partition the software into so-called genericity layers. We argue that federated architectures are at the heart of product lines, and we provide compelling arguments as to why federated architectures are a sound weapon in today's corporate strategy: they enable smooth enterprise integration and rapid change. We support our arguments with a real-world case: we successfully migrated a large global transaction and settlement system with many site-specific variations to a product line with a federated architecture. Moreover, we measured the success rate of this architectural modification effort by showing that the annual direct cost savings are of the order of millions of dollars during the deployment of the product line. Copyright © 2003 John Wiley & Sons, Ltd.

Structure of the highly repeated, long interspersed DNA family (LINE or L1Rn) of the rat.

E D'Ambrosio — 2007-04-02T14:42:31-00:00

Mol. Cell. Biol., Vol. 6, No. 2. (1 February 1986), pp. 411-424.

We present the DNA sequence of a 6.7-kilobase member of the rat long interspersed repeated DNA family (LINE or L1Rn). This member (LINE 3) is flanked by a perfect 14-base-pair (bp) direct repeat and is a full-length, or close-to-full-length, member of this family. LINE 3 contains an approximately 100-bp A-rich right end, a number of long (greater than 400-bp) open reading frames, and a ca. 200-bp G + C-rich (ca. 60%) cluster near each terminus. Comparison of the LINE 3 sequence with the sequence of about one-half of another member, which we also present, as well as restriction enzyme analysis of the genomic copies of this family, indicates that in length and overall structure LINE 3 is quite typical of the 40,000 or so other genomic members of this family which would account for as much as 10% of the rat genome. Therefore, the rat LINE family is relatively homogeneous, which contrasts with the heterogeneous LINE families in primates and mice. Transcripts corresponding to the entire LINE sequence are abundant in the nuclear RNA of rat liver. The characteristics of the rat LINE family are discussed with respect to the possible function and evolution of this family of DNA sequences.

Production with an assembly line process

Jon Neill — 2005-02-18T05:05:24-00:00

Economics of Innovation and New Technology, Vol. 14, No. 3. (April 2005), pp. 173-187.

A semiquantitative culture method for identifying intravenous-catheter-related infection

DG Maki — 2008-07-02T14:46:35-00:00

N Engl J Med, Vol. 296, No. 23. (9 June 1977), pp. 1305-1309.

We evaluated a semiquantitative culture technic for identifying infection due to intravenous catheters: rolling the catheter segment across blood agar. This method was compared to broth culture. Of 250 catheters studied, 225 (90%) had low-density colonization on semiquantitative culture (less than 15 colonies on the plate) although 49 (19.6%) of these grew some organisms in broth or on the plate. None of these catheters led to septicemia. Twenty-five catheters (10%) grew greater than or equal to 15 colonies by the semiquantitative technic; most gave confluent growth. Septicemia originated from four of these catheters (P = 0.008). Of 37 catheters exposed to bacteremias from distant foci of infection, four yielded matching growth in broth, whereas none were concordant with the blood isolate on semiquantitative culture. Local inflammation was associated with high-density colonization semiquantitative culture (P less than 0.001). The semiquantitative technic distinguishes infection (greater than or equal to 15 colonies) from contamination and is more specific in diagnosis of catheter-related septicemia than culture of the catheter in broth.

Fatal cardiac tamponade as a result of a peripherally inserted central venous catheter: a case report and review of the literature

Orme — 2007-12-04T14:33:09-00:00

Br. J. Anaesth. (4 July 2007), aem181.

We present a case of fatal cardiac tamponade that occurred in association with a peripherally inserted central catheter (PICC) inserted from the right antecubital fossa. Migration of the catheter from the right atrium within 24 h of insertion lead to the administration of a potassium-enriched sodium chloride solution into the pericardial space with the development of ST-segment elevation and progression to pulseless electrical activity and, subsequently, ventricular fibrillation. Although signs of tamponade were seen on echocardiography, we propose that myocardial hyperkalaemia from the diffusion of potassium through the epicardium accounted for some of the clinical picture. PICC lines carry a greater risk of migration because of the tip movement associated with arm abduction and, therefore, care must be taken to ensure that the catheter tip is correctly positioned to reduce this risk. When such catheters are used for intra-operative central venous access, we believe chest radiography is mandatory before fluid administration through the catheter, but that this is unnecessary when the catheter is being used solely for central venous pressure monitoring. The use of softer catheters may reduce the risk of vessel perforation. Once tamponade is suspected, all drugs and infusions administered via the catheter should be reviewed, the catheter aspirated and echocardiography performed urgently. This may be facilitated by the greater availability of limited bedside echocardiography within critical care units and theatre complexes. 10.1093/bja/aem181

The Use of Tissue Models for Vascular Access Training: Phase I of the Procedural Patient Safety Initiative

Mark Ault — 2006-05-11T21:59:00-00:00

Journal of General Internal Medicine, Vol. 21, No. 5. (May 2006), pp. 514-517.

Central Line Simulation: A New Training Algorithm

Britt — 2007-07-19T06:25:08-00:00

The American Surgeon, Vol. 73, No. 7. (July 2007), pp. 680-683.

Catheter-related bloodstream infections in intensive care units: a systematic review with meta-analysis

Ramritu — 2008-03-22T17:49:23-00:00

Journal of Advanced Nursing, Vol. 62, No. 1. (April 2008), pp. 3-21.

Clear Central Line Emergency Access Registry: A Multi-Center Study to Determine Resident Competency in Placement of Central Venous Catheters

AG Balls — 2008-01-28T16:26:06-00:00

Journal of Emergency Medicine, Vol. 33, No. 3. (October 2007), pp. 325-326.

368: Central Line Emergency Access Registry: A Multi-Center Study to Determine Resident Competency With Central Venous Catheter Insertion

A Balls — 2008-01-28T16:24:48-00:00

Annals of Emergency Medicine, Vol. 50, No. 3, Supplement 1. (September 2007), S115.

Ultrasound-Guided Internal Jugular Access: A Proposed Standardized Approach and Implications for Training and Practice

David Feller-Kopman — 2008-05-21T14:33:45-00:00

Chest, Vol. 132, No. 1. (1 July 2007), pp. 302-309.

In 2001, the Agency for Healthcare Research and Quality recommended the use of ultrasound for the placement of central venous catheters (CVCs) as one of their 11 practices to improve patient care. These recommendations were based on the results of several randomized clinical trials showing significantly improved overall success as well as reductions in complications. This article will describe the practical aspects of using ultrasound to guide placement of CVCs in the internal jugular vein in a "how I do it" approach, as well as review the practice management and training aspects related to incorporating ultrasound into daily practice. 10.1378/chest.06-2711

Preventing complications of central venous catheterization.

DC McGee — 2006-05-10T00:27:33-00:00

N Engl J Med, Vol. 348, No. 12. (20 March 2003), pp. 1123-1133.

Ultrasonic locating devices for central venous cannulation: meta-analysis.

D Hind — 2007-12-21T15:38:26-00:00

BMJ, Vol. 327, No. 7411. (16 August 2003)

OBJECTIVES: To assess the evidence for the clinical effectiveness of ultrasound guided central venous cannulation. DATA SOURCES: 15 electronic bibliographic databases, covering biomedical, science, social science, health economics, and grey literature. DESIGN: Systematic review and meta-analysis of randomised controlled trials. Populations Patients scheduled for central venous access. INTERVENTION REVIEWED: Guidance using real time two dimensional ultrasonography or Doppler needles and probes compared with the anatomical landmark method of cannulation. DATA EXTRACTION: Risk of failed catheter placement (primary outcome), risk of complications from placement, risk of failure on first attempt at placement, number of attempts to successful catheterisation, and time (seconds) to successful catheterisation. DATA SYNTHESIS: 18 trials (1646 participants) were identified. Compared with the landmark method, real time two dimensional ultrasound guidance for cannulating the internal jugular vein in adults was associated with a significantly lower failure rate both overall (relative risk 0.14, 95% confidence interval 0.06 to 0.33) and on the first attempt (0.59, 0.39 to 0.88). Limited evidence favoured two dimensional ultrasound guidance for subclavian vein and femoral vein procedures in adults (0.14, 0.04 to 0.57 and 0.29, 0.07 to 1.21, respectively). Three studies in infants confirmed a higher success rate with two dimensional ultrasonography for internal jugular procedures (0.15, 0.03 to 0.64). Doppler guided cannulation of the internal jugular vein in adults was more successful than the landmark method (0.39, 0.17 to 0.92), but the landmark method was more successful for subclavian vein procedures (1.48, 1.03 to 2.14). No significant difference was found between these techniques for cannulation of the internal jugular vein in infants. An indirect comparison of relative risks suggested that two dimensional ultrasonography would be more successful than Doppler guidance for subclavian vein procedures in adults (0.09, 0.02 to 0.38). CONCLUSIONS: Evidence supports the use of two dimensional ultrasonography for central venous cannulation.

Central line simulation: a new training algorithm.

RC Britt — 2008-02-28T00:04:16-00:00

Am Surg, Vol. 73, No. 7. (July 2007)

Recent development of a partial task simulator for central line placement has altered the training algorithm from one of supervised learning on patients to mannequin-based practice to proficiency before patient interaction. There are little data published on the efficacy of this type of simulator. We reviewed our initial resident experience with central line simulation. Education to proficiency using the CentralLine Man simulator is completed by all interns during orientation. At the completion of training, te residents were asked to complete a voluntary, anonymous questionnaire with a 5-point Likert scale as well as open-ended questions. Additionally, the residents were asked to maintain a log of the initial 10 central lines placed. Retrospective review of the questionnaire and logs were done with analysis of simulator experience as well as initial line experience. Seventeen trainees completed the central line simulation course and returned the initial survey. Before the course, the trainees had placed an average of 0.4 internal jugular (IJ) and 1 subclavian (SC) line. On the simulator, an average of 3 SC attempts and 2.5 IJ attempts led to resident comfort with the procedure. On the first attempt, the vessel was accessed after an average of 1.5 SC and 1.9 IJ needlesticks, which improved to 1 SC and 1.3 IJ by the fifth simulated attempt. A total of 4 pneumothorax and 5 carotid sticks were done. Overall, the residents were highly satisfied with the course with an average score of 4.8 for didactics, 4.8 for equipment, 4.5 for the mannequin, and 4.8 for practice opportunity. Nine of the 11 residents who completed logs felt the simulation improved performance on the patient. On the first patient attempt, an average of 1.8 needlesticks was done with an average of 1.3 by the tenth line. For the first patient line documented in the logs, comfort with the anatomy was rated 3.8 with comfort with the procedure rated 2.8. Central line simulation before actual performance on patients is useful and well regarded by the trainees, suggestive of a transference effect. Prospective evaluation is needed to further determine the impact of simulation on resident performance as well as patient outcomes.

On the formation of H-alpha line emission around classical T Tauri stars

Ryuichi Kurosawa — 2006-06-14T21:20:01-00:00

(9 May 2006)

We present radiative transfer models of the circumstellar environment of classical T Tauri stars, concentrating on the formation of the H-alpha emission. The wide variety of line profiles seen in observations are indicative of both inflow and outflow, and we therefore employ a circumstellar structure that includes both magnetospheric accretion and a disc wind. We perform systematic investigations of the model parameters for the wind and the magnetosphere to search for possible geometrical and physical conditions which lead to the types of profiles seen in observations. We find that the hybrid models can reproduce the wide range of profile types seen in observations, and that the most common profile types observed occupy a large volume of parameter space. Conversely, the most infrequently observed profile morphologies require a very specific set of models parameters. We find our model profiles are consistent with the canonical value of the mass-loss rate to mass-accretion rate ratio (mu=0.1) found in earlier magneto-hydrodynamic calculations and observations, but the models with 0.05<mu<0.2 are still in accord with observed H-alpha profiles. We investigate the wind contribution to the line profile as a function of model parameters, and examine the reliability of H-alpha as a mass accretion diagnostic. Finally, we examine the H-alpha spectroscopic classification used by Reipurth et. al, and discuss the basic physical conditions that are required to reproduce the profiles in each classified type.

Determinants for DNA target structure selectivity of the human LINE-1 retrotransposon endonuclease.

Kostas Repanas — 2007-07-23T08:04:46-00:00

Nucleic Acids Res (10 July 2007)

The human LINE-1 endonuclease (L1-EN) is the targeting endonuclease encoded by the human LINE-1 (L1) retrotransposon. L1-EN guides the genomic integration of new L1 and Alu elements that presently account for approximately 28% of the human genome. L1-EN bears considerable technological interest, because its target selectivity may ultimately be engineered to allow the site-specific integration of DNA into defined genomic locations. Based on the crystal structure, we generated L1-EN mutants to analyze and manipulate DNA target site recognition. Crystal structures and their dynamic and functional analysis show entire loop grafts to be feasible, resulting in altered specificity, while individual point mutations do not change the nicking pattern of L1-EN. Structural parameters of the DNA target seem more important for recognition than the nucleotide sequence, and nicking profiles on DNA oligonucleotides in vitro are less well defined than the respective integration site consensus in vivo. This suggests that additional factors other than the DNA nicking specificity of L1-EN contribute to the targeted integration of non-LTR retrotransposons.

Role of the Dnmt3 family in de novo methylation of imprinted and repetitive sequences during male germ cell development in the mouse.

Y Kato — 2007-12-03T14:46:28-00:00

Hum Mol Genet, Vol. 16, No. 19. (1 October 2007), pp. 2272-2280.

DNA methylation is an important epigenetic modification regulating various biological phenomena, including genomic imprinting and transposon silencing. It is known that methylation of the differentially methylated regions (DMRs) associated with paternally imprinted genes and of some repetitive elements occurs during male germ cell development in the mouse. We have performed a detailed methylation analysis of the paternally methylated DMRs (H19, Dlk1/Gtl2 and Rasgrf1), interspersed repeats [SineB1, intracisternal A particle (IAP) and Line1] and satellite repeats (major and minor) to determine the timing of this de novo methylation in male germ cells. Furthermore, we have examined the roles of the de novo methyltransferases (Dnmt3a and Dnmt3b) and related protein (Dnmt3L) in this process. We found that methylation of all DMRs and repeats occurred progressively in fetal prospermatogonia and was completed by the newborn stage. Analysis of newborn prospermatogonia from germline-specific Dnmt3a and Dnmt3b knockout mice revealed that Dnmt3a mainly methylates the H19 and Dlk1/Gtl2 DMRs and a short interspersed repeat SineB1. Both Dnmt3a and Dnmt3b were involved in the methylation of Rasgrf1 DMR and long interspersed repeats IAP and Line1. Only Dnmt3b was required for the methylation of the satellite repeats. These results indicate both common and differential target specificities of Dnmt3a and Dnmt3b in vivo. Finally, all these sequences showed moderate to severe hypomethylation in Dnmt3L-deficient prospermatogonia, indicating the critical function and broad specificity of this factor in de novo methylation.

Meiotic and epigenetic defects in Dnmt3L-knockout mouse spermatogenesis.

KE Webster — 2007-12-03T14:38:43-00:00

Proc Natl Acad Sci U S A, Vol. 102, No. 11. (15 March 2005), pp. 4068-4073.

The production of mature germ cells capable of generating totipotent zygotes is a highly specialized and sexually dimorphic process. The transition from diploid primordial germ cell to haploid spermatozoa requires genome-wide reprogramming of DNA methylation, stage- and testis-specific gene expression, mitotic and meiotic division, and the histone-protamine transition, all requiring unique epigenetic control. Dnmt3L, a DNA methyltransferase regulator, is expressed during gametogenesis, and its deletion results in sterility. We found that during spermatogenesis, Dnmt3L contributes to the acquisition of DNA methylation at paternally imprinted regions, unique nonpericentric heterochromatic sequences, and interspersed repeats, including autonomous transposable elements. We observed retrotransposition of an LTR-ERV1 element in the DNA from Dnmt3L-/- germ cells, presumably as a result of hypomethylation. Later in development, in Dnmt3L-/- meiotic spermatocytes, we detected abnormalities in the status of biochemical markers of heterochromatin, implying aberrant chromatin packaging. Coincidentally, homologous chromosomes fail to align and form synaptonemal complexes, spermatogenesis arrests, and spermatocytes are lost by apoptosis and sloughing. Because Dnmt3L expression is restricted to gonocytes, the presence of defects in later stages reveals a mechanism whereby early genome reprogramming is linked inextricably to changes in chromatin structure required for completion of spermatogenesis.

Meiotic catastrophe and retrotransposon reactivation in male germ cells lacking Dnmt3L.

D Bourc'his — 2007-12-03T14:34:25-00:00

Nature, Vol. 431, No. 7004. (2 September 2004), pp. 96-99.

Mammalian genomes employ heritable cytosine methylation in the long-term silencing of retrotransposons and genes subject to genomic imprinting and X chromosome inactivation. Little is known of the mechanisms that direct cytosine methylation to specific sequences. Here we show that DNA methyltransferase 3-like (Dnmt3L (ref. 1)) is expressed in testes during a brief perinatal period in the non-dividing precursors of spermatogonial stem cells at a stage where retrotransposons undergo de novo methylation. Deletion of the Dnmt3L gene prevented the de novo methylation of both long-terminal-repeat (LTR) and non-LTR retrotransposons, which were transcribed at high levels in spermatogonia and spermatocytes. Loss of Dnmt3L from early germ cells also caused meiotic failure in spermatocytes, which do not express Dnmt3L. Whereas dispersed repeated sequences were demethylated in mutant germ cells, tandem repeats in pericentric regions were methylated normally. This result indicates that the Dnmt3L protein might have a function in the de novo methylation of dispersed repeated sequences in a premeiotic genome scanning process that occurs in male germ cells at about the time of birth.

The SRA protein Np95 mediates epigenetic inheritance by recruiting Dnmt1 to methylated DNA

Jafar Sharif — 2007-11-12T08:10:26-00:00

Nature (11 November 2007)

Particle transport in asymmetric scanning-line optical tweezers

B Liesfeld — 2007-08-31T22:23:15-00:00

Physical Review E, Vol. 68, No. 5. (24 November 2003), 051907.

We describe a scanning-line optical tweezing technique with an asymmetric beam profile in the back focal plane of the microscope objective. The motion of a trapped particle along the scan line is studied as a function of beam asymmetry; and it is shown that this technique can be used to exert a constant lateral force on the particle; realizing purely optical constant-force tweezing. The observed effect is attributed in a geometric optics model to a non-zero lateral component of the scattering force.

Line Width Distributions in Single-Molecule Spectroscopy Due to Optical Saturation

L Kador — 2007-08-01T01:48:25-00:00

J. Phys. Chem. A, Vol. 102, No. 48. (26 November 1998), pp. 9745-9749.

Abstract: The paper deals with distributions of spectroscopic line widths of single molecules as measured in disordered solids at low temperatures. The influence of the random orientation of the dye molecules and, hence, of the different amount of power broadening on the fluorescence excitation spectra is investigated. The resulting line width distributions are calculated as a function of laser intensity and of the detection efficiency of the apparatus. It turns out that, for linearly polarized laser light, power broadening tends to give rise to asymmetric distributions that have a steep slope at narrow widths and a longer tail at broad widths. Possible implications for experimental line width histograms are discussed.

Optical trapping of colloidal particles and measurement of the defect line tension and colloidal forces in a thermotropic nematic liquid crystal

II Smalyukh — 2007-07-29T22:13:23-00:00

Applied Physics Letters, Vol. 86 (January 2005), 1913.

We demonstrate optical trapping and manipulation of transparent microparticles suspended in a thermotropic nematic liquid crystal with low birefringence. We employ the particle manipulation to measure line tension of a topologically stable disclination line and to determine colloidal interaction of particles with perpendicular surface anchoring of the director. The three-dimensional director fields and positions of the particles manipulated by laser tweezers are visualized by fluorescence confocal polarizing microscopy.

Holocene climate and landscape evolution East of the Pechora Delta, East-European Russian Arctic

Minna Valiranta — 2006-03-03T14:23:40-00:00

Quaternary Research, Vol. 59, No. 3. (May 2003), pp. 335-344.

This study presents a multiproxy record of Holocene environmental change in the region East of the Pechora Delta. A peat plateau profile (Ortino II) is analyzed for plant macrofossils, sediment type, loss on ignition, and radiocarbon dating. A paleosol profile (Ortino III) is described and radiocarbon dated. A previously published peat plateau profile (Ortino I) was analyzed for pollen and conifer stomata, loss on ignition, and radiocarbon dating. The interpretation of the latter site is reassessed in view of new evidence. Spruce immigrated to the study area at about 8900 14C yr B.P. Peatland development started at approximately the same time. During the Early Holocene Hypsithermal taiga forests occupied most of the present East-European tundra and peatlands were permafrost free. Cooling started after 5000 14C yr B.P., resulting in a retreat of forests and permafrost aggradation. Remaining forests disappeared from the study area around 3000 14C yr B.P., coinciding with more permafrost aggradation. The retreat of forests resulted in landscape instability and the redistribution of sand by eolian activity. The displacement of the Arctic forest line and permafrost zones indicates a warming of at least 2-3[deg]C in mean July and annual temperatures during the Early Holocene. At least two cooling periods can be recognized for the second half of the Holocene, starting at about 4800 and 3000 14C yr B.P.

Edge co-occurrence in natural images predicts contour grouping performance.

WS Geisler — 2006-01-15T12:24:39-00:00

Vision Res, Vol. 41, No. 6. (March 2001), pp. 711-724.

The human brain manages to correctly interpret almost every visual image it receives from the environment. Underlying this ability are contour grouping mechanisms that appropriately link local edge elements into global contours. Although a general view of how the brain achieves effective contour grouping has emerged, there have been a number of different specific proposals and few successes at quantitatively predicting performance. These previous proposals have been developed largely by intuition and computational trial and error. A more principled approach is to begin with an examination of the statistical properties of contours that exist in natural images, because it is these statistics that drove the evolution of the grouping mechanisms. Here we report measurements of both absolute and Bayesian edge co-occurrence statistics in natural images, as well as human performance for detecting natural-shaped contours in complex backgrounds. We find that contour detection performance is quantitatively predicted by a local grouping rule derived directly from the co-occurrence statistics, in combination with a very simple integration rule (a transitivity rule) that links the locally grouped contour elements into longer contours.

Employing fuzzy logic in feature diagrams to model variability in software product-lines

S Robak — 2006-08-27T20:25:56-00:00

Engineering of Computer-Based Systems, 2003. Proceedings. 10th IEEE International Conference and Workshop on the (2003), pp. 305-311.

The possible features of software product line members may vary according to the needs of particular market segments or purposes. The assessment of what will be common and what will be variable may, e.g., result from market strategies. Customer profiles may be used to model an otherwise anonymous market, each requiring in turn a specific sets of variant features. Identical feature sets may be prioritized in different ways for specific customer groups. The paper proposes a system description based on a feature diagram tree, annotated with weighted variant features in the product line context. The principle how some variant features may be described on the basis of fuzzy logic is introduced and discussed. As the proposed description also integrates the external cross-tree constraints, it leads to an improved homogeneity of the descriptive logic. This opens the opportunity to integrate additional tools into the scenario, e.g., generators or support for constraint based reasoning. The use of the proposed approach is demonstrated by the example of a simple car description.

Spectrum formation in supernovae - Numerical techniques

RG Eastman — 2008-05-13T12:19:33-00:00

Astrophys. J., Vol. 412 (August 1993), pp. 731-751.

The study combines several novel techniques for spectrum simulation in the Eddington computer program which solves the comoving frame equation of transfer coupled with the statistical and radiative equilibrium equations. One of these is a generalization of the accelerated lambda iteration (ALI) scheme to include an approximate frequency-derivative operator. This greatly enhances the convergence rate of ALI in optically thick, high-velocity shear flows. Another is a partial linearization technique which is capable of efficiently solving a very large number of rate equations on a moderately sized computer. An expansion opacity and emissivity approximation is derived which makes it possible to determine the effect on the transfer and statistical equilibrium of a very large number of lines not explicitly represented in the frequency grid and additionally to treat line-blanketing from species not explicitly included in the rate equations. The utility of these techniques is illustrated with models of two supernovae.

Determination of the Line Tension of Giant Vesicles from Pore-Closing Dynamics

Narayanan Srividya — 2008-05-27T21:31:55-00:00

J. Phys. Chem. B (27 May 2008)

Abstract: Giant vesicles generated from synthetic and natural lipids such as phosphatidylcholines are useful models for understanding mechanical properties of cell membranes. Line tension is the one-dimensional force enabling the closing of transient pores on cell membranes. Transient pores were repeatedly and reproducibly formed on the membrane edge of giant vesicles generated from synthetic and natural phosphatidylcholines employing a nitrogen-pumped coumarin dye laser (440 nm). Line tension was determined at room temperature from closing of these pores that occurred over several seconds when the radius of the vesicle could be considered to be constant. The value of line tension depends on the nature of the lipid for single lipid systems, which, at room temperature, yielded a vesicle bilayer region in the gel, fluid, or mixed gel and fluid phases. The line tension for vesicles generated from phosphatidylcholines with saturated acyl chains of lengths of 1218 carbon atoms ranges from 1 to 12 pN, exhibiting an increase with chain length. Vesicles generated from the natural Egg-PC, which is a mixture of lipids, are devoid of phase transition and exhibited the largest value of line tension (32 pN). This value is much larger than that estimated from the line tensions of vesicles obtained from lipids with homologous acyl chains. This study, to our knowledge, is the first to employ laser ablation to generate transient pores and determine line tension from the rate of pore closure and demonstrate a relationship between line tension and acyl chain length.

Effect of Line Tension on the Lateral Organization of Lipid Membranes

Ana Garcia-Saez — 2007-11-13T00:26:33-00:00

J. Biol. Chem., Vol. 282, No. 46. (16 November 2007), pp. 33537-33544.

The principles of organization and functioning of cellular membranes are currently not well understood. The raft hypothesis suggests the existence of domains or rafts in cell membranes, which behave as protein and lipid platforms. They have a functional role in important cellular processes, like protein sorting or cell signaling, among others. Theoretical work suggests that the interfacial energy at the domain edge, also known as line tension, is a key parameter determining the distribution of domain sizes, but there is little evidence of how line tension affects membrane organization. We have investigated the effects of the line tension on the formation and stability of liquid ordered domains in model lipid bilayers with raft-like composition by means of time-lapse confocal microscopy coupled to atomic force microscopy. We varied the hydrophobic mismatch between the two phases, and consequently the line tension, by modifying the thickness of the disordered phase with phosphatidylcholines of different acyl chain length. The temperature of domain formation, the dynamics of domain growth, and the distribution of domain sizes depend strongly on the thickness difference between the domains and the surrounding membrane, which is related to line tension. When considering line tension calculated from a theoretical model, our results revealed a linear increase of the temperature of domain formation and domain growth rate with line tension. Domain budding was also shown to depend on height mismatch. Our experiments contribute significantly to our knowledge of the physical-chemical parameters that control membrane organization. Importantly, the general trends observed can be extended to cellular membranes. 10.1074/jbc.M706162200

Empirical Equation to Account for the Length Dependence of Line Tension

R David — 2007-10-20T23:56:46-00:00

Langmuir (19 October 2007)

Abstract: Measured values of the three-phase line tension in the literature are correlated with the spreading parameter and with the radii of the drops or bubbles under investigation. The latter dependence contradicts an assumption of the modified Young equation. We suggest an alternative empirical formulation that describes the data consistently, and we discuss its possible physical significance.

Budding and domain shape transformations in mixed lipid films and bilayer membranes

JL Harden — 2007-12-18T22:21:49-00:00

Physical Review E (Statistical, Nonlinear, and Soft Matter Physics), Vol. 72, No. 1. (2005)

We study the stability and shapes of domains with spontaneous curvature in fluid films and membranes, embedded in a surrounding membrane with zero spontaneous curvature. These domains can result from the inclusion of an impurity in a fluid membrane or from phase separation within the membrane. We show that for small but finite line and surface tensions and for finite spontaneous curvatures, an equilibrium phase of protruding circular domains is obtained at low impurity concentrations. At higher concentrations, we predict a transition from circular domains, or caplets, to stripes. In both cases, we calculate the shapes of these domains within the Monge representation for the membrane shape. With increasing line tension, we show numerically that there is a budding transformation from stable protruding circular domains to spherical buds. We calculate the full phase diagram and demonstrate two triple points of, respectively, bud-flat-caplet and flat-stripe-caplet coexistence.

Contact angle and line tension dependence on curvature

G Navascues — 2008-01-17T01:25:38-00:00

Chemical Physics Letters, Vol. 82, No. 3. (15 September 1981), pp. 586-588.

Contact angle and line tension dependence on the curvature of the three-phase contact region has been analysed. It has been found that curvature effects can be neglected when the drop radius is larger than the thickness of the contact region except for small contact angles.

Coupling between Line Tension and Domain Contact Angle in Heterogeneous Membranes

Kevin Towles — 2008-01-17T01:20:56-00:00

Biochimica et Biophysica Acta (BBA) - Biomembranes, Vol. In Press, Accepted Manuscript

Line Tension and Coalescence in Heterogeneous Membranes

KB Towles — 2007-12-06T18:11:07-00:00

Langmuir (21 November 2007)

Abstract: Membrane inhomogeneity gives rise to a perturbation energy that may be manifested as line tension between regions of different compositions. Here we calculate the perturbation energy of a phase-separated fluid membrane composed of domains embedded in a continuous phase and relate it to the line tension in the system. We find that the effective line tension due to the thickness mismatch between the phases varies nonmonotonically as a function of the domain size and spacing when those decrease below about 20 nm. Although we find that the characteristic time scale for domain coalescence increases with domain size, the coalescence time for domains on the order of 25 to 50 nm may be as long as several days. The time scale for domain coalescence is found, quite surprisingly, to be maximal when the bending and area moduli of the domain and continuous phase are similar and to decrease when one phase is stiffer than the other. Domain stability is also found to vary as a function of spacing; as a result, small domains on the order of 5 nm become unstable and tend to coalesce when the domain-phase area fraction increases above 0.5, whereas larger domains on the order of 50 nm become unstable only when the area fraction increases above 0.8.

Domain Nucleation Rates and Interfacial Line Tensions in Supported Bilayers of Ternary Mixtures Containing Galactosylceramide

Craig Blanchette — 2007-12-11T16:42:25-00:00

Biophys. J. (7 December 2007), biophysj.107.122572.

Domains within the plane of the plasma membrane, referred to as membrane rafts, have been a topic of considerable interest in the field of membrane biophysics. Although model membrane systems have been used extensively to study lipid phase behavior as it relates to the existence of rafts, very little work has focused on either the initial stage of lipid domain nucleation, or the relevant physical parameters such as temperature and interfacial line tension which control nucleation. In this work we utilize a method in which the kinetic process of lipid domain nucleation is imaged by atomic force microscopy (AFM) and modeled using classical theory of nucleation to map interfacial line tension in ternary lipid mixtures. These mixtures consist of a fluid phase lipid component (1,2-Dilauroyl-sn-Glycero-3-Phosphocholine (DLPC), 1-Palmitoyl-2-Oleoyl-sn-Glycero-3-Phosphocholine (POPC), or 1,2-Dioleoyl-sn-Glycero-3-Phosphocholine (DOPC)), a solid phase component (galactosylceramide (GalCer)) and cholesterol. Interfacial line tension measurements of GalCer-rich domains track with our previously measured area/perimeter (A/P) ratios and height mismatches measured here. Line tension also follows known trends in cholesterol interactions and partitioning, as we observed previously with A/P ratios. Our line tension measurements are discussed in combination with recent line tension measurements by Baumgart and coworkers to address line tension regulation by cholesterol and the dynamic nature of membrane rafts. 10.1529/biophysj.107.122572

Line tension at lipid phase boundaries regulates formation of membrane vesicles in living cells

Dina Vind-Kezunovic — 2008-06-12T23:57:37-00:00

Biochimica et Biophysica Acta (BBA) - Biomembranes, Vol. In Press, Accepted Manuscript

Line detection and segmentation in historical church registers

M Feldbach — 2007-10-04T05:18:39-00:00

Document Analysis and Recognition, 2001. Proceedings. Sixth International Conference on (2001), pp. 743-747.

For being able to automatically acquire the information recorded in church registers and other historical scriptures, the writing on these documents has to be recognized. This paper describes algorithms for transforming the paper documents into a representation of text apt to be used as input for an automatic text recognizer. The automatic recognition of old handwritten scriptures is difficult for two main reasons. Lines of text in general are not straight and ascenders and descenders of adjacent lines interfere. The algorithms described in this paper provide ways to reconstruct the path of the lines of text using an approach of gradually constructing line segments until a unique line of text is formed. In addition, the single lines are segmented and an output in form of a raster image is provided. The method was applied to church registers. They were written between the 17th and 19th Century. Line segmentation was found to be successful in 97% of all samples

A statistically based, highly accurate text line segmentation method

J Liang — 2007-10-04T05:21:08-00:00

ICDAR, Proc. 5th (1999), pp. 551-554.

This paper describes a text-line identification and segmentation technique that is probability based, where all probabilities are estimated from an extensive training set of various kind of measurements of distances between the terminal and non-terminal entities and between the textline and the text-block entities with which the algorithm works. The off-line probabilities estimated in the training then drive all decisions in the on-line segmentation algorithm. On the UW-III database of some...

Text Line Segmentation of Historical Documents: a Survey

Laurence Likforman-Sulem — 2007-10-04T05:25:06-00:00

Document Analysis and Recognition, International Journal on, Vol. 9 (10 April 2007), pp. 123-138.

There is a huge amount of historical documents in libraries and in various National Archives that have not been exploited electronically. Although automatic reading of complete pages remains, in most cases, a long-term objective, tasks such as word spotting, text/image alignment, authentication and extraction of specific fields are in use today. For all these tasks, a major step is document segmentation into text lines. Because of the low quality and the complexity of these documents (background noise, artifacts due to aging, interfering lines),automatic text line segmentation remains an open research field. The objective of this paper is to present a survey of existing methods, developed during the last decade, and dedicated to documents of historical interest.

Text line segmentation in handwritten document using a production system

S Nicolas — 2007-10-04T04:01:46-00:00

Frontiers in Handwriting Recognition, 2004. IWFHR-9 2004. Ninth International Workshop on (2004), pp. 245-250.

We present in this paper a digitization project of cultural heritage manuscripts and we discuss the underlying problems, particularly those relative to document analysis. Considering the drawbacks of traditional methods for text line extraction in handwritten documents, we propose to adopt a new approach for handwritten page segmentation, based on a traditional problem solving framework used in artificial intelligence.

Handwritten Document Offline Text Line Segmentation

C Weliwitage — 2007-10-04T04:06:10-00:00

Digital Image Computing: Technqiues and Applications, 2005. DICTA ' 05. Proceedings (2005), pp. 184-187.

Point-to-Line Mappings and Hough Transforms

Prabir Bhattacharya — 2007-06-16T02:55:08-00:00

Digital and Image Geometry: Advanced Lectures (2001), pp. 201-212.

Nearly 40 years ago Hough showed how a point-to-line mapping that takes collinear points into concurrent lines can be used to detect collinear sets of points, since such points give rise to peaks where the corresponding lines intersect. Over the past 30 years many variations and generalizations of Hough's idea have been proposed. Hough's mapping was linear, but most or all of the mappings studied since then have been nonlinear, and take collinear points into concurrent curves rather than concurrent lines; little or no work has appeared in the pattern recognition literature on mappings that take points into lines. This paper deals with point-to-line mappings in the real projective plane. (We work in the projective plane to avoid the need to deal with special cases in which collinear points are mapped into parallel, rather than concurrent, lines.) We review basic properties of linear point-to-point mappings (collineations) and point-to-line mappings (correlations), and show that any one-to-one point-to-line mapping that takes collinear points into concurrent lines must in fact be linear. We describe ways in which the matrices of such mappings can be put into canonical form, and show that Hough's mapping is only one of a large class of inequivalent mappings. We show that any one-to-one point-to-line mapping that has an incidence-symmetry property must be linear and must have a symmetric matrix which has a diagonal canonical form. We establish useful geometric properties of such mappings, especially in cases where their matrices define nonempty conics.

Plane-based Calibration of a Camera with Varying Focal Length: the Centre Line Constraint

Pierre Gurdjos — 2006-08-28T07:58:33-00:00

The British Machine Vision Conference (2001)

This paper deals with the problem of calibrating a (moving) camera with varying focal length, from views of a planar pattern with a known Euclidean structure. The main issue under discussion is to find a new method whose complexity does not dramatically increase with the number of views, contrary to existing methods. Our contribution is to relate this calibration problem to the Centre Line (CL) constraint, that is the principal point locus when planar figures are in perpective correspondence, in accordance with Poncelet's theorem. We demonstrate that the CL equation is irrespective of the focal length and holds for each view, with only three unknown parameters whose values are constant in the images. We define its analytic equation with coefficients computed from the world-plane to image homography matrices. An important aspect is that we can make use of it as a linear cost function that expresses a geometric error (instead of algebraic errors in existing methods). We explain why an "optimal" solutioncan be obtained when pixels are rectangular. The simulations on synthetic data and an application with real images confirm the two strong points of our method with respect to existing ones: a lower computation cost and a better system conditioning that permits to obtain more accurate results.

Using Vanishing Points for Camera Calibration

B Caprile — 2006-08-10T05:39:32-00:00

International Journal of Computer Vision, Vol. 4, No. 2. (March 1990), pp. 127-139.