bluuebunny/crossref_metadata_2025 huggingface dataset:
Treatment of log yard runoff with a continuous fixed film bioreactor
Authors: Liao Charles , Finnbogason Thomas W. , Duff Sheldon J.B.
Published: June 2008

Runoff is generated at log yards when precipitation comes into contact with logs, wood debris, and equipment at outdoor wood processing, sorting and storage facilities. Log yard runoff, which can be toxic and have high levels of biochemical oxygen demand (BOD), chemical oxygen demand (COD), and tannin and lignin (T&L), is a potential threat to nearby receiving environments. Runoff samples were collected from two sawmills located in British Columbia (BC). The runoff samples collected had BOD ranging from 16 to 371 mg/L, COD from 230 to 2660 mg/L, and tannin and lignin from 200 to 680 mg/L of tannic acid. Four runoff samples were acutely toxic according to the Microtox® toxicity test. A continuous lab-scale fixed film bioreactor was used to treat the runoff over a range of temperature (5–30 °C) and hydraulic retention times (4–24 h). The reactor was capable of treating runoff with BOD removal ranging from 73.0% to 97.6%, COD removal ranging from 48.0% to 76.9%, and tannin and lignin removal ranging from 27.8% to 60.1%. There appeared to be a transitional change in the makeup of the microbial community in the reactor as the temperature decreased from 15 °C to 10 °C. The reactor was able to remove all acute toxicity at 30 °C, but at lower temperatures treated runoff remained acutely toxic.
Use of goldfish to monitor wastewater and reuse water for xenobiotics
Authors: Kerr Jennifer L. , Guo Zhenyu , Smith Daniel W. , Goss Greg G. , Belosevic Miodrag
Published: June 2008

Goldfish were exposed to either treated municipal effluent (FE wastewater) or reuse water produced through membrane ultrafiltration (MF reuse water) or membrane ultrafiltration followed by activated carbon filtration (MCF wastewater) for up to 90 days. The xenobiotics present in the wastewater were identified using gas chromatography – mass spectroscopy and the efficacy of their removal by membrane ultrafiltration and activated carbon filtration were determined. At various time points post-exposure to wastewater or reuse water the following biological parameters were assessed: vitellogenin (Vtg) induction, immune gene expression, and mitogen-induced proliferation of blood leukocytes. Membrane ultrafiltration alone did not remove xenobiotics from FE wastewater, while activated carbon filtration efficiently reduced the levels of most xenobiotics. Vitellogenin was induced in fish exposed to both FE wastewater and MF reuse water, but not in fish exposed to MCF reuse water. Messenger ribonucleic acid (mRNA) expression of select immune genes (tumor necrosis factor alpha, colony stimulating factor receptor-1) were up-regulated in FE and MF exposed fish on days 7 and 21 post exposure, while Toll-like receptor 22 mRNA level was similar in fish exposed to wastewater or control water. Prolonged exposure of fish to FE and MF wastewaters caused a significant reduction in the mitogen-induced proliferation of blood leukocytes. Our results suggest that goldfish may be used as biosentinels for xenobiotics present in wastewater and reuse water.
Stockage et stabilité à long terme de boues d’épuration municipales décontaminées et stabilisées par voie chimique ou biologique
Authors: Tremblay Joannie , Blais Jean-François , Drogui Patrick , Mercier Guy
Published: June 2008

The objective of this research was to evaluate the effects of sewage sludge storage on biological and physico-chemical parameters of sludge treated by different stabilization and decontamination processes. Three sludge storage methods were tested: inside at stable temperature (21 ± 2 °C), outside during summer (May–October), and inside at different temperatures to simulate the winter season. An increase of the sludge pH (approximately 8.0–8.5) and an odour removal process were measured following a 5-month storage period, and this, for all conditions of sludge treatments and storage options. The sanitary conditions of the sludge improved, because the fecal coliforms were completely eliminated, and fecal streptococci and salmonella were significantly reduced. The results also revealed that the pH adjustment, near neutrality, of sludge treated by acid processes (Stabiox and Metix-AC) is preferable before a long storage period. This allows a better biodegradation of the organic matter and the production of less odorous sludge. Sludge neutralization also decreases phosphorus and metals concentrations in drainage waters. The preservation of the acid conditions remains however useful during a short storage period, by allowing to avoid a fast resumption of the nauseous odours. Overall, the different temperatures had few effects on sludge characteristics after the 5-month storage period.
The implementation of single-sludge step-feed anoxic–aerobic process in a domestic wastewater treatment plant
Authors: Xu Aotian , Young Stephanie , Zhang Yanqiu
Published: June 2008

The single-sludge step-feed anoxic–aerobic process (SSFAOP) was implemented in the Xuzhou wastewater treatment plant (WWTP) in China to enhance ammonia and nitrogen removal performance. Influent flow splitting and step feeding in the aerobic zone were used to provide high concentrations of mixed liquor suspended solids (MLSS), long solids retention time (SRT), and short nitrification time. After implementation, removal efficiencies of ammonia nitrogen >90% and total Kjeldahl nitrogen (TKN) >80% were achieved. The amount of waste activated sludge (WAS) was significantly reduced, and sludge bulkings were eliminated. The application of SSFAOP also reduced capital and operational costs.
Response of seven hardwood tree species to herbicide, rototilling, and legume cover at two southern Quebec plantation sites
Authors: Cogliastro Alain , Gagnon Daniel , Coderre Daniel , Bhéreur Pierre
Published: June 2008

Two experimental plantations of valuable hardwoods were established in southern Quebec, at the northern limit of the North American deciduous forest, to examine the effects of three weed control treatments on the growth of tree seedlings. Treatments of herbicide, rototilling, and sowing of a legume cover (Lotuscorniculatus L. and Trifoliumrepens L.) were applied to seven tree species (Fraxinusamericana L., Juglansnigra L., Prunusserotina Ehrh., Quercusalba L., Quercusmacrocarpa Michx., Quercusrubra L., Tiliaamericana L.). A control treatment, retaining existing herbaceous vegetation, was also included. After three growing seasons tree growth was highest in the herbicide and rototilling treatments. Improved growth was associated with high foliar nitrogen, and sometimes phosphorus, content. The growth gains provided by weed control were reduced on the site with the poorest soil drainage. Despite the introduction of herbaceous legumes, the weed biomass increased during the first 2 years, and tree growth in this treatment was rarely superior to the control. The growth obtained for some species in the best treatment, generally the herbicide, was similar to that attained farther south in Ontario.
Improving the precision of tree height estimates
Authors: Romesburg H. Charles , Mohai Paul
Published: June 2008

Two models for estimating tree height using a hypsometer, termed the two-step and one-step models, are computer simulated to determine the precision of estimates as a function of the model and the observer's viewing position about the tree. Rules of thumb guiding model selection and viewing position are formulated.
Bending of a conifer branch at subfreezing temperatures: implications for snow interception
Authors: Schmidt R. A. , Pomeroy J. W.
Published: June 2008

Ice crystals in cells of frozen wood increase the wood's modulus of elasticity so that branches become more rigid at colder temperatures. As temperature increases after a snowstorm, melting of crystals within the cells allows increased bending of branches under intercepted snow loads. Measurements of the force that produced a 10-cm deflection of branch tips of subalpine fir (Abieslasiocarpa (Hook.) Nutt.) and lodgepole pine (Pinuscontorta var. latifolia Engelm.) showed a linear decrease as temperature rose from −12 to 0 °C. Model predictions for the bending of a tapered branch supported the hypothesis that increased bending can explain unloading of intercepted snow under certain conditions when warming occurs after snowstorms.
CRITICAL PERCOLATION OF FREE PRODUCT OF GROUPS
Authors: KOZÁKOVÁ IVA
Published: June 2008

In this article we study percolation on the Cayley graph of a free product of groups.

The critical probability pcof a free product G1* G2* ⋯ * Gnof groups is found as a solution of an equation involving only the expected subcritical cluster size of factor groups G1, G2, …, Gn. For finite groups this equation is polynomial and can be explicitly written down. The expected subcritical cluster size of the free product is also found in terms of the subcritical cluster sizes of the factors. In particular, we prove that pcfor the Cayley graph of the modular group PSL2(ℤ) (with the standard generators) is 0.5199…, the unique root of the polynomial 2p5- 6p4+ 2p3+ 4p2- 1 in the interval (0, 1).

In the case when groups Gican be "well approximated" by a sequence of quotient groups, we show that the critical probabilities of the free product of these approximations converge to the critical probability of G1* G2* ⋯ * Gnand the speed of convergence is exponential. Thus for residually finite groups, for example, one can restrict oneself to the case when each free factor is finite.

We show that the critical point, introduced by Schonmann, pexpof the free product is just the minimum of pexpfor the factors.
THE BRAID ROOK MONOID
Authors: GODELLE EDDY
Published: June 2008

In linear algebraic monoid theory, the Renner monoids play the role of the Weyl groups in linear algebraic group theory. It is well known that Weyl groups are Coxeter groups, and that we can associate a Hecke algebra and an Artin–Tits group to each Coxeter group. The question of the existence of a Hecke algebra associated with each Renner monoid has been positively answered. In this paper we discuss the question of the existence of an equivalent of the Artin–Tits groups in the framework of Renner monoids. We consider the seminal case of the rook monoid and introduce a new length function.
LEARNING TO BEHAVE IN SPACE: A QUALITATIVE SPATIAL REPRESENTATION FOR ROBOT NAVIGATION WITH REINFORCEMENT LEARNING
Authors: FROMMBERGER LUTZ
Published: June 2008

The representation of the surrounding world plays an important role in robot navigation, especially when reinforcement learning is applied. This work uses a qualitative abstraction mechanism to create a representation of space consisting of the circular order of detected landmarks and the relative position of walls towards the agent's moving direction. The use of this representation does not only empower the agent to learn a certain goal-directed navigation strategy faster compared to metrical representations, but also facilitates reusing structural knowledge of the world at different locations within the same environment. Acquired policies are also applicable in scenarios with different metrics and corridor angles. Furthermore, gained structural knowledge can be separated, leading to a generally sensible navigation behavior that can be transferred to environments lacking landmark information and/or totally unknown environments.
ON PREPROCESSING AND ANTISYMMETRY IN DE NOVO PEPTIDE SEQUENCING: IMPROVING EFFICIENCY AND ACCURACY
Authors: NING KANG , YE NAN , LEONG HON WAI
Published: June 2008

Peptide sequencing plays a fundamental role in proteomics. Tandem mass spectrometry, being sensitive and efficient, is one of the most commonly used techniques in peptide sequencing. Many computational models and algorithms have been developed for peptide sequencing using tandem mass spectrometry. In this paper, we investigate general issues in de novo sequencing, and present results that can be used to improve current de novo sequencing algorithms. We propose a general preprocessing scheme that performs binning, pseudo-peak introduction, and noise removal, and present theoretical and experimental analyses on each of the components. Then, we study the antisymmetry problem and current assumptions related to it, and propose a more realistic way to handle the antisymmetry problem based on analysis of some datasets. We integrate our findings on preprocessing and the antisymmetry problem with some current models for peptide sequencing. Experimental results show that our findings help to improve accuracies for de novo sequencing.
CLUSTERING OF MAIN ORTHOLOGS FOR MULTIPLE GENOMES
Authors: FU ZHENG , JIANG TAO
Published: June 2008

The identification of orthologous genes shared by multiple genomes is critical for both functional and evolutionary studies in comparative genomics. While it is usually done by sequence similarity search and reconciled tree construction in practice, recently a new combinatorial approach and high-throughput system MSOAR for ortholog identification between closely related genomes based on genome rearrangement and gene duplication has been proposed in Fu et al.1 MSOAR assumes that orthologous genes correspond to each other in the most parsimonious evolutionary scenario, minimizing the number of genome rearrangement and (postspeciation) gene duplication events. However, the parsimony approach used by MSOAR limits it to pairwise genome comparisons. In this paper, we extend MSOAR to multiple (closely related) genomes and propose an ortholog clustering method, called MultiMSOAR, to infer main orthologs in multiple genomes. As a preliminary experiment, we apply MultiMSOAR to rat, mouse, and human genomes, and validate our results using gene annotations and gene function classifications in the public databases. We further compare our results to the ortholog clusters predicted by MultiParanoid, which is an extension of the well-known program InParanoid for pairwise genome comparisons. The comparison reveals that MultiMSOAR gives more detailed and accurate orthology information, since it can effectively distinguish main orthologs from inparalogs.
IMPROVING THE PERFORMANCE OF PROTEIN THREADING USING INSERTION/DELETION FREQUENCY ARRAYS
Authors: ELLROTT KYLE , GUO JUN-TAO , OLMAN VICTOR , XU YING
Published: June 2008

As a protein evolves, not every part of the amino acid sequence has an equal probability of being deleted or for allowing insertions, because not every amino acid plays an equally important role in maintaining the protein structure. However, the most prevalent models in fold recognition methods treat every amino acid deletion and insertion as equally probable events. We have analyzed the alignment patterns for homologous and analogous sequences to determine patterns of insertion and deletion, and used that information to determine the statistics of insertions and deletions for different amino acids of a target sequence. We define these patterns as insertion/deletion (indel) frequency arrays (IFAs). By applying IFAs to the protein threading problem, we have been able to improve the alignment accuracy, especially for proteins with low sequence identity. We have also demonstrated that the application of this information can lead to an improvement in fold recognition.
DECONVOLUTING BAC–GENE RELATIONSHIPS USING A PHYSICAL MAP
Authors: WU YONGHUI , LIU LAN , CLOSE TIMOTHY J. , LONARDI STEFANO
Published: June 2008

Deconvolution of relationships between bacterial artificial chromosome (BAC) clones and genes is a crucial step in the selective sequencing of regions of interest in a genome. It often includes combinatorial pooling of unique probes obtained from the genes (unigenes), and screening of the BAC library using the pools in a hybridization experiment. Since several probes can hybridize to the same BAC, in order for the deconvolution to be achievable the pooling design has to be able to handle a large number of positives. As a consequence, smaller pools need to be designed, which in turn increases the number of hybridization experiments, possibly making the entire protocol unfeasible. We propose a new algorithm that is capable of producing high-accuracy deconvolution even in the presence of a weak pooling design, i.e. when pools are rather large. The algorithm compensates for the decrease of information in the hybridization data by taking advantage of a physical map of the BAC clones. We show that the right combination of combinatorial pooling and our algorithm not only dramatically reduces the number of pools required, but also successfully deconvolutes the BAC–gene relationships with almost perfect accuracy. Software is available on request from the first author.
BETTER GENECHIP MICROARRAY LAYOUTS BY COMBINING PROBE PLACEMENT AND EMBEDDING
Authors: DE CARVALHO SÉRGIO A. , RAHMANN SVEN
Published: June 2008

The microarray layout problem is a generalization of the border length minimization problem, and asks to distribute oligonucleotide probes on a microarray and to determine their embeddings in the deposition sequence in such a way that the overall quality of the resulting synthesized probes is maximized. Because of its inherent computational complexity, it is traditionally attacked in several phases: partitioning, placement, and re-embedding. We present the first algorithm, Greedy+, that combines placement and embedding and that results in improved layouts in terms of border length and conflict index (a more realistic measure of probe quality), both on arrays of random probes and on existing Affymetrix GeneChip® arrays. We also present a detailed study on the layouts of the latest GeneChip arrays, and show how Greedy+ can further improve layout quality by as much as 12% in terms of border length and 35% in terms of conflict index.
THE ROLE OF COMPLEMENTARY ACTORS IN THE DEVELOPMENT OF INNOVATION IN SMALL FIRMS
Authors: MAZZAROL TIM , REBOUD SOPHIE
Published: June 2008

This study examines the findings of a survey of small, high innovator firms and their assessment of the risks and benefits of forming strategic alliances with third party "complementors". The study found that the entrepreneurs of these small innovator firms were willing to form strategic alliances where such collaboration would assist in reducing customer perceptions of risk in the adoption of their innovation, while also enhancing the customer's understanding of the innovation. However, the entrepreneur of the small firm also needed to be confident that the alliance would allow him or her to retain control over the quality of the final outcome to their customer. These findings suggest that education of the entrepreneur in the development and management of strategic networks may be a useful enhancement to the process of innovation in small firms.
Incremental cluster-based retrieval using compressed cluster-skipping inverted files
Authors: Altingovde Ismail Sengor , Demir Engin , Can Fazli , Ulusoy Özgür
Published: June 2008

We propose a unique cluster-based retrieval (CBR) strategy using a new cluster-skipping inverted file for improving query processing efficiency. The new inverted file incorporates cluster membership and centroid information along with the usual document information into a single structure. In our incremental-CBR strategy, during query evaluation, both best(-matching) clusters and the best(-matching) documents of such clusters are computed together with a single posting-list access per query term. As we switch from term to term, the best clusters are recomputed and can dynamically change. During query-document matching, only relevant portions of the posting lists corresponding to the best clusters are considered and the rest are skipped. The proposed approach is essentially tailored for environments where inverted files are compressed, and provides substantial efficiency improvement while yielding comparable, or sometimes better, effectiveness figures. Our experiments with various collections show that the incremental-CBR strategy using a compressed cluster-skipping inverted file significantly improves CPU time efficiency, regardless of query length. The new compressed inverted file imposes an acceptable storage overhead in comparison to a typical inverted file. We also show that our approach scales well with the collection size.
"Where do you come from? and where are you going?"
Authors: Vardi Moshe Y.
Published: June 2008

The noted management consulting firm Booz Allen Hamilton recently issued a report identifying the world's 10 most enduring institutions of the 20th and 21st centuries.
The emergence of a networking primitive in wireless sensor networks
Authors: Levis Philip , Brewer Eric , Culler David , Gay David , Madden Samuel , Patel Neil , Polastre Joe , Shenker Scott , Szewczyk Robert , Woo Alec
Published: June 2008

The wireless sensor network community approached networking abstractions as an open question, allowing answers to emerge with time and experience. The Trickle algorithm has become a basic mechanism used in numerous protocols and systems. Trickle brings nodes to eventual consistency quickly and efficiently while remaining remarkably robust to variations in network density, topology, and dynamics. Instead of flooding a network with packets, Trickle uses a "polite gossip" policy to control send rates so each node hears just enough packets to stay consistent. This simple mechanism enables Trickle to scale to 1000-fold changes in network density, reach consistency in seconds, and require only a few bytes of state yet impose a maintenance cost of a few sends an hour. Originally designed for disseminating new code, experience has shown Trickle to have much broader applicability, including route maintenance and neighbor discovery. This paper provides an overview of the research challenges wireless sensor networks face, describes the Trickle algorithm, and outlines several ways it is used today.
Revising the guidelines for associate-degree transfer curriculum in computer science
Authors: Hawthorne Elizabeth K.
Published: June 2008

The ACM Two-Year College Education Committee (TYCEC) is finalizing revisions to its computer science transfer curriculum in conjunction with the five-year interim review of the CS2001 volume. These 2008 transfer guidelines will update the
Guidelines for Associate Degree Programs in Computer Science
published in 2003 by ACM and IEEE-CS. The committee also extends a warm welcome to our newest member recruited to assist with this undertaking, Assistant Professor Anita M. Wright of Camden County College, Blackwood, NJ.
Reflections on teaching abstraction and other soft ideas
Authors: Hazzan Orit
Published: June 2008

This essay relies on my research works about abstraction conducted over the past decade. It addresses the importance of increasing students' awareness to the concept of abstraction and other soft ideas and suggests several approaches for the teaching of soft ideas in general and of the concept of abstraction in particular.
The impact of providing project choices in CS1
Authors: Stone Jeffrey A. , Madigan Elinor M.
Published: June 2008

CS educators are constantly faced with the challenge of engaging students who have neither the interest nor skill level necessary to succeed in an introductory course. One potential solution is to allow students to choose their projects from a set of comparable alternatives, each of which represents a different problem domain. This paper reports on the results of a two-year study designed to measure the impact of project choice on student outcomes in a CS1-style course for non-majors. The results suggest that the gender plays a major role in both the projects chosen and student outcomes.
Central lactate metabolism regulates food intake
Authors: Lam Carol K. L. , Chari Madhu , Wang Penny Y. T. , Lam Tony K. T.
Published: June 2008

The central nervous system regulates food intake (FI) and body weight (BW), but the associated mechanisms remain to be elucidated. Here we report that central injections of lactate reduced FI and BW in rodents. Inhibition of central lactate metabolism to pyruvate with the lactate dehydrogenase inhibitor oxamate abolished the central effects of lactate on FI and BW. Conversely, central injections of pyruvate recapitulated the effects of lactate. Finally, inhibition of central lactate metabolism prevented the ability of circulating lactate to lower FI and BW. Together, the data indicate that activation of central lactate metabolism lowers FI and BW.
Coupling of Modular High-Temperature Gas-Cooled Reactor with Supercritical Rankine Cycle
Authors: Zhu Shutang , Tang Ying , Xiao Kun , Zhang Zuoyi
Published: June 2008

This paper presents investigations on the possible combination of modular high-temperature gas-cooled reactor (MHTGR) technology with the supercritical (SC) steam turbine technology and the prospective deployments of the MHTGR SC power plant. Energy conversion efficiency of steam turbine cycle can be improved by increasing the main steam pressure and temperature. Investigations on SC water reactor (SCWR) reveal that the development of SCWR power plants still needs further research and development. The MHTGR SC plant coupling the existing technologies of current MHTGR module design with operation experiences of SC FPP will achieve high cycle efficiency in addition to its inherent safety. The standard once-reheat SC steam turbine cycle and the once-reheat steam cycle with life-steam have been studied and corresponding parameters were computed. Efficiencies of thermodynamic processes of MHTGR SC plants were analyzed, while comparisons were made between an MHTGR SC plant and a designed advanced passive PWR - AP1000. It was shown that the net plant efficiency of an MHTGR SC plant can reach 45% or above, 30% higher than that of AP1000 (35% net efficiency). Furthermore, an MHTGR SC plant has higher environmental competitiveness without emission of greenhouse gases and other pollutants.
Differential Effects of Leptin on the Invasive Potential of Androgen‐Dependent and ‐Independent Prostate Carcinoma Cells
Authors: Deo Dayanand D. , Rao Ashwin P. , Bose Saideep S. , Ouhtit Allal , Baliga Surendra B. , Rao Shilpa A. , Trock Bruce J. , Thouta Rajesh , Raj Madhwa HG , Rao Prakash N.
Published: June 2008

Obesity has been linked with an increased risk of prostate cancer. The formation of toxic free oxygen radicals has been implicated in obesity mediated disease processes. Leptin is one of the major cytokines produced by adipocytes and controls body weight homeostasis through food intake and energy expenditure. The rationale of the study was to determine the impact of leptin on the metastatic potential of androgen‐sensitive (LNCaP) cells as well as androgen‐insensitive (PC‐3 and DU‐145) cells. At a concentration of 200_nm, LNCaP cells showed a significant increase (20% above control; P < .0001) in cellular proliferation without any effect on androgen‐insensitive cells. Furthermore, exposure to leptin caused a significant (P < .01 to P < .0001) dose‐dependent decrease in migration and invasion of PC3 and Du‐145 prostate carcinoma cell lines. At the molecular level, exposure of androgen‐independent prostate cancer cells to leptin stimulates the phosphorylation of MAPK at early time point as well as the transcription factor STAT3, suggesting the activation of the intracellular signaling cascade upon leptin binding to its cognate receptor. Taken together, these results suggest that leptin mediates the invasive potential of prostate carcinoma cells, and that this effect is dependent on their androgen sensitivity.
A Novel Design of 4-Class BCI Using Two Binary Classifiers and Parallel Mental Tasks
Authors: Geng Tao , Gan John Q. , Dyson Matthew , Tsui Chun SL , Sepulveda Francisco
Published: June 2008

A novel 4-class single-trial brain computer interface (BCI) based on two (rather than four or more) binary linear discriminant analysis (LDA) classifiers is proposed, which is called a “parallel BCI.” Unlike other BCIs where mental tasks are executed and classified in a serial way one after another, the parallel BCI uses properly designed parallel mental tasks that are executed on both sides of the subject body simultaneously, which is the main novelty of the BCI paradigm used in our experiments. Each of the two binary classifiers only classifies the mental tasks executed on one side of the subject body, and the results of the two binary classifiers are combined to give the result of the 4-class BCI. Data was recorded in experiments with both real movement and motor imagery in 3 able-bodied subjects. Artifacts were not detected or removed. Offline analysis has shown that, in some subjects, the parallel BCI can generate a higher accuracy than a conventional 4-class BCI, although both of them have used the same feature selection and classification algorithms.
On‐Chip All‐Optical Switching and Memory by Silicon Photonic Crystal Nanocavities
Authors: Notomi Masaya , Tanabe Takasumi , Shinya Akihiko , Kuramochi Eiichi , Taniyama Hideaki
Published: June 2008

We review our recent studies on all‐optical switching and memory operations based on thermo‐optic and carrier‐plasma nonlinearities both induced by two‐photon absorption in silicon photonic crystal nanocavities. Owing to high‐Q and small volume of these photonic crystal cavities, we have demonstrated that the switching power can be largely reduced. In addition, we demonstrate that the switching time is also reduced in nanocavity devices because of their short diffusion time. These features are important for all‐optical nonlinear processing in silicon photonics technologies, since silicon is not an efficient optical nonlinear material. We discuss the effect of the carrier diffusion process in our devices, and demonstrate improvement in terms of the response speed by employing ion‐implantation process. Finally, we show that coupled bistable devices lead to all‐optical logic, such as flip‐flop operation. These results indicate that a nanocavity‐based photonic crystal platform on a silicon chip may be a promising candidate for future on‐chip all‐optical information processing in a largely integrated fashion.
Stress Induced Effects for Advanced Polarization Control in Silicon Photonics Components
Authors: Xu D.-X. , Ye W. N. , Janz S. , Delâge A. , Cheben P. , Lamontagne B. , Post E. , Waldron P.
Published: June 2008

We review the use of the oxide cladding stress‐induced photoelastic effect to modify the polarization dependent properties in silicon‐on‐insulator (SOI) waveguide components, and highlight characteristics particular to this high index contrast (HIC) systems. The birefringence in SOI waveguides has its origin in the electromagnetic boundary conditions at the waveguide boundaries, and can be further modified by the presence of stress in the waveguiding materials. With typical stress levels in SiO2 films, which are often used as the upper cladding, the waveguide effective index can be altered anisotropically up to the order of 10−3 for ridges with heights ranging from 1 μm to 5 μm. This effect can be used effectively to counter the waveguide geometrical birefringence, allowing the waveguide cross‐section profiles to be optimized for design criteria other than null geometrical birefringence. Design strategies are developed for using stress engineering to achieve a variety of functions. Polarization insensitive arrayed waveguide gratings (AWGs), polarization insensitive ring resonators, and polarization splitters and filters are demonstrated using these design principles.
Tuning of the Optical Properties in Photonic Crystals Made of Macroporous Silicon
Authors: Kitzerow Heinz-S. , Matthias Heinrich , Schweizer Stefan L. , van Driel Henry M. , Wehrspohn Ralf B.
Published: June 2008

It is well known that robust and reliable photonic crystal structures can be manufactured with very high precision by electrochemical etching of silicon wafers, which results in two‐ and three‐dimensional photonic crystals made of macroporous silicon. However, tuning of the photonic properties is necessary in order to apply these promising structures in integrated optical devices. For this purpose, different effects have been studied, such as the infiltration with addressable dielectric liquids (liquid crystals), the utilization of Kerr‐like nonlinearities of the silicon, or free‐charge carrier injection by means of linear (one‐photon) and nonlinear (two‐photon) absorptions. The present article provides a review, critical discussion, and perspectives about state‐of‐the‐art tuning capabilities.
Professor Alfred Jost: The Builder of Modern Sex Differentiation
Authors: Josso N.
Published: June 2008

Professor Alfred Jost (1916–1991) is famous for his discovery of the Müllerian inhibitor, now called anti-Müllerian hormone (AMH) or Müllerian inhibiting substance (MIS). Alfred Jost resolved the controversy surrounding the mechanism of somatic sex differentiation by proving that male characteristics must be imposed on the fetus by the testicular hormones testosterone and AMH, respectively responsible for the virilization of the Wolffian ducts, urogenital sinus and external genitalia and for the regression of Müllerian ducts. In the absence or inactivity of these hormones, the fetus becomes phenotypically female. Alfred Jost was also a pioneer through his work on testicular differentiation, in collaboration with Solange Magre. He was the first to show that testicular organization is heralded by the development of pre-Sertoli cells, which progressively surround germ cells to form seminiferous tubules. Alfred Jost did not rely only on his brilliant mind. He distrusted theories built on suboptimal experimental data and believed that intelligence was powerless without technical skill. His search for elegant, effective techniques led him to apply surgical methods to fetal endocrinology. He was also a fascinating teacher, particularly for pre-doctoral students. He died aged 75, having retired from the Collège de France, but still active as the Secrétaire Perpétuel of the French Science Academy.
In-vitro Characterization of Androgen Receptor Mutations Associated with Complete Androgen Insensitivity Syndrome Reveals Distinct Functional Deficits
Authors: Werner R. , Zhan J. , Gesing J. , Struve D. , Hiort O.
Published: June 2008

Adequate androgen receptor (AR) function is crucial for male sex development and maintenance of secondary male characteristics. Mutations in the AR lead to androgen insensitivity syndrome (AIS) characterized by an end-organ resistance to androgens. The clinical appearance of individuals with 46,XY karyotype and an AR mutation varies widely from normal male to the ultimate completely female phenotype of complete androgen insensitivity syndrome (CAIS). We have analyzed the androgen receptor missense mutations P723S, P904S, and H917R, clinically associated with CAIS, which were described to have a normal maximum androgen binding (Bmax) but elevated equilibrium dissociation constants (Kd’s) and compared their properties with the F916X deletion mutant, leading to the loss of the last four amino acids of the AR. Functional analysis allowed a quantitative and qualitative discrimination of these mutants in transactivation, amino-terminal/carboxy-terminal (N/C)-interaction, and coactivation capacity, varying widely with each distinct mutation. We conclude that mutations in the AR have to be characterized meticulously, not only to prove any quantitative functional deficit as a proof of consequence, but also to gain knowledge on qualitative functional properties. This is necessary as a possible link to genotype-phenotype correlation in AIS, but also with respect to medical decision making in CAIS.
Mutations in the RSPO1 Coding Region Are Not the Main Cause of Canine SRY-Negative XX Sex Reversal in Several Breeds
Authors: De Lorenzi L. , Groppetti D. , Arrighi S. , Pujar S. , Nicoloso L. , Molteni L. , Pecile A. , Cremonesi F. , Parma P. , Meyers-Wallen V.
Published: June 2008

This report details a case of SRY-negative XX sex reversal in a mixed breed dog and surveys affected dogs of several breeds for mutations in RSPO1 coding regions. Genomic DNA from the mixed breed case was evaluated for mutations in candidate genes. Sequencing identified a homozygous G to A transition in RSPO1 exon 4 that changes a highly conserved amino acid codon in the thrombospondin domain. The possibility that this was a single nucleotide polymorphism (SNP) could not be excluded by genotyping family members. Therefore, the coding region of RSPO1 was sequenced in a survey of affected dogs, which identified a T to C transition (exon 3) in some, the above G to A transition (exon 4) in others, and no change in the remaining affected dogs. Genotypes at these base pair positions were not uniquely associated with the affected phenotype in any breed, indicating the identified transitions are most likely SNPs, not causative mutations for this canine disorder. However, the possibility that polymorphisms play a modifier role, such as changing threshold or severity of phenotypic expression in a mixed breed dog, cannot be excluded. This study emphasizes the importance of canine pedigree, breed, and population studies in evaluating candidate mutations.
Sexual Development of the Urodele Amphibian Pleurodeles waltl
Authors: Dumond H. , Kuntz S. , Chesnel A. , Ko C.-I. , Wallacides A. , Chardard D. , Flament S.
Published: June 2008

Pleurodeles waltl is a urodele amphibian that displays a ZZ/ZW genetic mode of sex determination involving a putative W-borne dominant determinant. This determining pathway can be environmentally inhibited since heat treated ZW larvae undergo a functional female to male sex reversal. Moreover, both genetic sexes can be reversed by treatment of larvae with steroid hormones suggesting they are the major players in the differentiation process. Indeed we demonstrated that i) aromatase expression and activity increase just before ovarian differentiation, ii) aromatase inhibitors induce a female to male sex reversal, iii) estrogens induce male to female sex reversal whereas the opposite is obtained with non-aromatizable androgens, iv) steroidogenic factor 1 and estrogen receptor alpha both display a female-enriched expression following the increase in aromatase activity. The role of endogenous hormones was investigated in a parabiosis model. Surprisingly, in ZW/ZZ associations, the ZW gonad could not differentiate suggesting that the ZZ parabiont produces an inhibiting factor, prior to ovarian differentiation. The role of AMH in this process is discussed, keeping in mind that Müllerian ducts are maintained in males. The development of antibodies and new molecular tools in the near future should help us to better understand the sexual development of this vertebrate.
Colojejunal Fistula Resulting from a D-PEJ Feeding Tube
Authors: Zielinski Martin D. , Cima Robert R.
Published: June 2008

Numerous procedures have been developed to provide adequate enteral nutrition to patients with gastrointestinal disorders. Previously, operative placement of a feeding gastrostomy or jejunostomy tube was the accepted means of gaining chronic enteral access. However, improved technology and experience with endoscopic techniques have quickly replaced primary operative placement of enteral access. Direct percutaneous endoscopic jejunostomy (D-PEJ) is a procedure that was designed to deliver enteral feeding solutions for patients with proximal disease after unsatisfactory results from percutaneous endoscopic gastrostomy tubes with jejunal extensions (PEG-J). As with any procedure, it is associated with complications. We present the first reported case of a colojejunal fistula resulting from a D-PEJ placement. While D-PEJ has been shown to be relatively safe, complications related to the inherent limitations of the procedure need to be considered when the patient experiences unusual post-procedure symptoms and worked up appropriately.
Role of the Calpain System in Pulmonary Vein Connexin Remodeling in Dogs with Atrial Fibrillation
Authors: Zhang Wei , Ma Xiao , Zhong Ming , Zheng Zhaotong , Li Li , Wang Zhihao , Zhang Yun
Published: June 2008

Objectives: Changes in connexins and calpains of the myocardial sleeve of the pulmonary vein and the left atrium were investigated in chronic atrial fibrillation (AF) animal models. Background: There are no reports of changes in the calpain system and connexins in the pulmonary vein where AF is initiated. Methods: An AF animal model was prepared by rapid pacing of the right atrium for 8 weeks. Histological changes of pulmonary veins were analyzed by Masson trichrome staining, and mRNA as well as protein expression of connexins and calpains were measured by real-time fluorescence quantitative PCR and Western blotting. Results: In AF dogs, the fibrous collagen reticulum surrounding individual myocardial cells was reduced or disrupted. In the myocardial sleeve of the AF dogs, Cx40 protein expression was significantly downregulated compared to the control group (60.78 ± 10.91 vs. 88.31 ± 14.73, p < 0.05), but calpain 1 was significantly upregulated (94.00 ± 7.24 vs. 81.77 ± 5.82, p < 0.05), and they were negatively correlated (r = –0.66, p < 0.05). Cx40 protein expression was significantly lower in the myocardial sleeve tissue than in the left atrium in the AF dogs (60.78 ± 10.91 vs. 91.38 ± 17.16, p < 0.05). Conclusions: Varied gap junctional remodeling around the pulmonary vein may be one of the underlying mechanisms for pulmonary vein-left atrial reentry. During AF, the calpain system of the myocardial sleeve tissue is activated and may hydrolyze Cx40 protein, which is a possible important molecular mechanism for gap junctional remodeling that merits further investigation.
Intrasplenic or Subperitoneal Hepatocyte Transplantation to Increase Survival after Surgically Induced Hepatic Failure?
Authors: Gäbelein G. , Nüssler A.K. , Morgott F. , Ping Y. , Nüssler N. , Neuhaus P. , Glanemann M.
Published: June 2008

Background: As a basis for future clinical questions, we evaluated the efficacy of hepatocyte transplantation in a surgical model using a subperitoneal or intrasplenic approach for cell implantation. Methods: In rats, acute liver failure was induced by subtotal hepatectomy. Series of allogenic hepatocyte transplantations were performed by varying cell number, site, and sequence of cell transplantation. Results: Following subperitoneal or intrasplenic cell implantation subsequent to liver surgery, no survival benefit was achieved when compared to the control groups. However, intrasplenic cell implantation 24 h prior to liver surgery revealed a statistically significantly higher animal survival (72 vs. 29%). Conclusion: According to our experience, both timing and site of cell implantation played an important role in hepatocyte transplantation. Intrasplenic hepatocyte transplantation 1 day before liver surgery showed the best results in terms of survival. Consequently, we were able to establish a model of hepatocyte transplantation which may be the basis for further investigations evaluating potential treatment modalities to overcome deleterious postoperative liver insufficiency.
Cardiac Microvascular Endothelial Cells Express a Functional Ca2+-Sensing Receptor
Authors: Berra Romani Roberto , Raqeeb Abdul , Laforenza Umberto , Scaffino Manuela Federica , Moccia Francesco , Avelino-Cruz Josè Everardo , Oldani Amanda , Coltrini Daniela , Milesi Veronica , Taglietti Vanni , Tanzi Franco
Published: June 2008

The mechanism whereby extracellular Ca2+ exerts the endothelium-dependent control of vascular tone is still unclear. In this study, we assessed whether cardiac microvascular endothelial cells (CMEC) express a functional extracellular Ca2+-sensing receptor (CaSR) using a variety of techniques. CaSR mRNA was detected using RT-PCR, and CaSR protein was identified by immunocytochemical analysis. In order to assess the functionality of the receptor, CMEC were loaded with the Ca2+-sensitive fluorochrome, Fura-2/AM. A number of CaSR agonists, such as spermine, Gd3+, La3+ and neomycin, elicited a heterogeneous intracellular Ca2+ signal, which was abolished by disruption of inositol 1,4,5-trisphosphate (InsP3) signaling and by depletion of intracellular stores with cyclopiazonic acid. The inhibition of the Na+/Ca2+ exchanger upon substitution of extracellular Na+ unmasked the Ca2+ signal triggered by an increase in extracellular Ca2+ levels. Finally, aromatic amino acids, which function as allosteric activators of CaSR, potentiated the Ca2+ response to the CaSR agonist La3+. These data provide evidence that CMEC express CaSR, which is able to respond to physiological agonists by mobilizing Ca2+ from intracellular InsP3-sensitive stores.
Unilateral Spiny Hyperkeratosis
Authors: Mevorah Baruch , Gat Andrea , Golan Haim , Brenner Sarah
Published: June 2008

We describe the first case of unilateral spiny hyperkeratosis (SH) of the left hand, review the literature and discuss possible patho- mechanisms. SH can be sporadic or familial, often appearing in healthy individuals. However, there is an association with various malignancies in a significant number of the sporadic cases. Although there is no satisfactory explanation of this association, we agree with previous authors that a patient with SH appearing in adult life should be evaluated and followed for the presence of malignancy. Other patients with SH may suffer from a variety of nonmalignant diseases, which may be coincidental or causally related. SH is not a premalignant lesion of the skin and should not be confused with porokeratosis which has a malignant potential. Except for excision of individual lesions, there is no permanent cure.
High Risk of Cognitive and Functional Decline after Postoperative Delirium
Authors: Bickel Horst , Gradinger Reiner , Kochs Eberhard , Förstl Hans
Published: June 2008

Background/Aims: The aim of the study was to investigate the association of postoperative delirium with the outcomes of cognitive impairment, functional disability and death. Methods: Hip surgery patients aged 60 years or over (n = 200) underwent preoperative and daily postoperative assessment of their cognitive status during hospital stay. Outcome variables were determined at an average of 8 and 38 months after discharge from hospital. Results: Fourty-one patients developed postoperative delirium. Delirium was a strong independent predictor of cognitive impairment and the occurrence of severe dependency in activities of daily living. The associations were more marked for the long- than for the short-term outcome. Thirty-eight months after discharge from hospital, 53.8% of the surviving patients with postoperative delirium suffered from cognitive impairment, as compared to only 4.4% of the nondelirious participants. Logistic regression analysis adjusted for age, sex, medical comorbidity and preoperative cognitive performance revealed highly significant associations between delirium and cognitive impairment (OR = 41.2; 95% CI = 4.3–396.2), subjective memory decline (OR = 6.2; 95% CI = 1.5–25.8) and incident need for long-term care (OR = 5.6; 95% CI = 1.6–19.7). Conclusion: The present study confirms a poor prognosis after delirium in elderly patients. The findings suggest that delirium does not simply persist for a certain time but also predicts a future cognitive decline with an increased risk of dementia.