bluuebunny/crossref_metadata_2025 huggingface dataset:
Growth hormone-releasing hormone as an agonist of the ghrelin receptor GHS-R1a
Authors: Casanueva Felipe F. , Camiña Jesus P. , Carreira Marcos C. , Pazos Yolanda , Varga Jozsef L. , Schally Andrew V.
Published: December 2008

Ghrelin synergizes with growth hormone-releasing hormone (GHRH) to potentiate growth hormone (GH) response through a mechanism not yet fully characterized. This study was conducted to analyze the role of GHRH as a potential ligand of the ghrelin receptor, GHS-R1a. The results show that hGHRH(1–29)NH
2
(GHRH) induces a dose-dependent calcium mobilization in HEK 293 cells stably transfected with GHS-R1a an effect not observed in wild-type HEK 293 cells. This calcium rise is also observed using the GHRH receptor agonists JI-34 and JI-36. Radioligand binding and cross-linking studies revealed that calcium response to GHRH is mediated by the ghrelin receptor GHS-R1a. GHRH activates the signaling route of inositol phosphate and potentiates the maximal response to ghrelin measured in inositol phosphate turnover. The presence of GHRH increases the binding capacity of
125
I-ghrelin in a dose dependent-fashion showing a positive binding cooperativity. In addition, confocal microscopy in CHO cells transfected with GHS-R1a tagged with enhanced green fluorescent protein shows that GHRH activates the GHS-R1a endocytosis. Furthermore, the selective GHRH-R antagonists, JV-1–42 and JMR-132, act also as antagonists of the ghrelin receptor GHS-R1a. Our findings suggest that GHRH interacts with ghrelin receptor GHS-R1a, and, in consequence, modifies the ghrelin-associated intracellular signaling pathway. This interaction may represent a form of regulation, which could play a putative role in the physiology of GH regulation and appetite control.
Relation between vaginal birth and pelvic organ prolapse
Authors: SZE EDDIE H.M. , HOBBS GERRY
Published: December 2008

Objective. To evaluate the relation between vaginal birth and pelvic organ prolapse quantification (POPQ) stages III and IV prolapse and whether each additional vaginal birth is associated with an increase in pelvic support defects. Design. Prospective cross‐sectional study. Setting. Gynecology clinic in a University Hospital. Population: Four hundred and fifty‐eight nulliparas and 892 multiparas, including 272 with one, 299 with two and 321 with at least three term vaginal deliveries. Methods. In a Human Investigation Committee approved‐study, the pelvic support of nulliparas and multiparas who only had term vaginal deliveries was evaluated for prolapse using the POPQ system. Main outcome measure. 1. Difference in POPQ stages III and IV prolapse between nulliparas and multiparas. 2. Difference in POPQ stage distribution among nulliparas and multiparas who had one, two, and at least three term vaginal deliveries. Results. Compared with nulliparas, the odds ratios of having POPQ stage II defect and stage III or IV prolapse associated with multiparas was 2.95 (95% CI: 2.06–4.24) and 1.01 (95% CI: 0.40–2.79), respectively. The prevalence of POPQ stage II defect among nulliparas and multiparas that had one, two, and at least three term vaginal deliveries was 25% (119/458), 50% (137/272), 66% (198/299), and 69% (220/321), respectively (p<0.001), while 1% (6/458), 1% (4/272), 2% (7/299), and 2% (8/321), respectively, had POPQ stage III or IV prolapse (p = 0.618). Conclusions. Vaginal birth is not associated with POPQ stages III and IV prolapse, but it is associated with an increase in POPQ stage II defect.
Uterine necrosis following selective embolization for postpartum hemorrhage using absorbable material
Authors: COULANGE LAURÈNE , BUTORI NOÉMIE , LOFFROY ROMARIC , FILIPUZZI LAURENCE , CERCUEIL JEAN PIERRE , DOUVIER SERGE , SAGOT PAUL , KRAUSE DENIS , TIXIER HERVÉ
Published: December 2008

Embolization of the uterine arteries with resorbable material is an effective treatment for postpartum hemorrhage. Cases of uterine necrosis were already described but with non‐resorbables particles. We report two exceptional cases of uterine necrosis with failure of conservative treatment following selective embolization with gelatine.
A genetic programming-based approach to the classification of multiclass microarray datasets
Authors: Liu Kun-Hong , Xu Chun-Gui
Published: December 2008

Motivation: Feature selection approaches have been widely applied to deal with the small sample size problem in the analysis of micro-array datasets. For the multiclass problem, the proposed methods are based on the idea of selecting a gene subset to distinguish all classes. However, it will be more effective to solve a multiclass problem by splitting it into a set of two-class problems and solving each problem with a respective classification system.

Results: We propose a genetic programming (GP)-based approach to analyze multiclass microarray datasets. Unlike the traditional GP, the individual proposed in this article consists of a set of small-scale ensembles, named as sub-ensemble (denoted by SE). Each SE consists of a set of trees. In application, a multiclass problem is divided into a set of two-class problems, each of which is tackled by a SE first. The SEs tackling the respective two-class problems are combined to construct a GP individual, so each individual can deal with a multiclass problem directly. Effective methods are proposed to solve the problems arising in the fusion of SEs, and a greedy algorithm is designed to keep high diversity in SEs. This GP is tested in five datasets. The results show that the proposed method effectively implements the feature selection and classification tasks.

Contact:  lkhqz@163.com; khliu1977@gmail.com

Supplementary information:  Supplementary data are available at Bioinformatics online.
Byrsonima fagifolia Niedenzu Apolar Compounds with Antitubercular Activity
Authors: Higuchi C. T. , Sannomiya M. , Pavan F. R. , Leite S. R. A. , Sato D. N. , Franzblau S. G. , Sacramento L. V. S. , Vilegas W. , Leite C. Q. F.
Published: December 2008

Bioassay‐guided fractionation of the chloroform extract of Byrsonima fagifolia leaves led to the isolation of active antitubercular compounds alkane dotriacontane (Minimal Inhibitory Concentration—MIC, 62.5 μg mL−1), triterpenoids as bassic acid (MIC = 2.5 μg mL−1), α‐amyrin acetate (MIC = 62.5 μg mL−1), a mixture of lupeol, α‐ and β‐amyrin (MIC = 31.5 μg mL−1) and a mixture of lupeol, and acetates of α‐ and β‐amyrin (MIC = 31.5 μg mL−1). The antimycobacterial activity was determined by the Microplate Alamar Blue Assay (MABA) and the structures of promising compounds were determined by spectroscopic analysis. This investigation constitutes the first report of a chemical and antitubercular study of apolar compounds from B. fagifolia Niedenzu (IK).
Revisiting Adjusted ADA Scores for the U.S. Congress, 1947–2007
Authors: Anderson Sarah , Habel Philip
Published: December 2008

This paper replicates and extends Groseclose, Levitt, and Snyder, “Comparing Interest Group Scores Across Time and Chambers: Adjusted ADA Scores for the U.S. Congress,” which appeared in the American Political Science Review (1999/93:33–50). We replicate the most recent unpublished extension by Dr. Groseclose and research assistants for years 1947–1999, and then we extend the analysis to include years 2000 through 2007. We make available inflation-adjusted ADA scores from 1947 through 2007, allowing scholars to incorporate the most recent interest group scores into their analyses.
The A- and B-type nuclear lamin networks: microdomains involved in chromatin organization and transcription
Authors: Shimi Takeshi , Pfleghaar Katrin , Kojima Shin-ichiro , Pack Chan-Gi , Solovei Irina , Goldman Anne E. , Adam Stephen A. , Shumaker Dale K. , Kinjo Masataka , Cremer Thomas , Goldman Robert D.
Published: December 2008

The nuclear lamins function in the regulation of replication, transcription, and epigenetic modifications of chromatin. However, the mechanisms responsible for these lamin functions are poorly understood. We demonstrate that A- and B-type lamins form separate, but interacting, stable meshworks in the lamina and have different mobilities in the nucleoplasm as determined by fluorescence correlation spectroscopy (FCS). Silencing lamin B1 (LB1) expression dramatically increases the lamina meshwork size and the mobility of nucleoplasmic lamin A (LA). The changes in lamina mesh size are coupled to the formation of LA/C-rich nuclear envelope blebs deficient in LB2. Comparative genomic hybridization (CGH) analyses of microdissected blebs, fluorescence in situ hybridization (FISH), and immunofluorescence localization of modified histones demonstrate that gene-rich euchromatin associates with the LA/C blebs. Enrichment of hyperphosphorylated RNA polymerase II (Pol II) and histone marks for active transcription suggest that blebs are transcriptionally active. However, in vivo labeling of RNA indicates that transcription is decreased, suggesting that the LA/C-rich microenvironment induces promoter proximal stalling of Pol II. We propose that different lamins are organized into separate, but interacting, microdomains and that LB1 is essential for their organization. Our evidence suggests that the organization and regulation of chromatin are influenced by interconnections between these lamin microdomains.
Aberrant chromatin at genes encoding stem cell regulators in human mixed-lineage leukemia
Authors: Guenther Matthew G. , Lawton Lee N. , Rozovskaia Tatiana , Frampton Garrett M. , Levine Stuart S. , Volkert Thomas L. , Croce Carlo M. , Nakamura Tatsuya , Canaani Eli , Young Richard A.
Published: December 2008

Mixed-lineage leukemia (MLL) fusion proteins are potent inducers of leukemia, but how these proteins generate aberrant gene expression programs is poorly understood. Here we show that the MLL-AF4 fusion protein occupies developmental regulatory genes important for hematopoietic stem cell identity and self-renewal in human leukemia cells. These MLL-AF4-bound regions have grossly altered chromatin structure, with histone modifications catalyzed by trithorax group proteins and DOT1 extending across large domains. Our results define direct targets of the MLL fusion protein, reveal the global role of epigenetic misregulation in leukemia, and identify new targets for therapeutic intervention in cancer.
Cas6 is an endoribonuclease that generates guide RNAs for invader defense in prokaryotes
Authors: Carte Jason , Wang Ruiying , Li Hong , Terns Rebecca M. , Terns Michael P.
Published: December 2008

An RNA-based gene silencing pathway that protects bacteria and archaea from viruses and other genome invaders is hypothesized to arise from guide RNAs encoded by CRISPR loci and proteins encoded by thecasgenes. CRISPR loci contain multiple short invader-derived sequences separated by short repeats. The presence of virus-specific sequences within CRISPR loci of prokaryotic genomes confers resistance against corresponding viruses. The CRISPR loci are transcribed as long RNAs that must be processed to smaller guide RNAs. Here we identifiedPyrococcus furiosusCas6 as a novel endoribonuclease that cleaves CRISPR RNAs within the repeat sequences to release individual invader targeting RNAs. Cas6 interacts with a specific sequence motif in the 5′ region of the CRISPR repeat element and cleaves at a defined site within the 3′ region of the repeat. The 1.8 angstrom crystal structure of the enzyme reveals two ferredoxin-like folds that are also found in other RNA-binding proteins. The predicted active site of the enzyme is similar to that of tRNA splicing endonucleases, and concordantly, Cas6 activity is metal-independent.cas6is one of the most widely distributed CRISPR-associated genes. Our findings indicate that Cas6 functions in the generation of CRISPR-derived guide RNAs in numerous bacteria and archaea.
Circadian activity and abundance rhythms of the Neurospora clock transcription factor WCC associated with rapid nucleo–cytoplasmic shuttling
Authors: Schafmeier Tobias , Diernfellner Axel , Schäfer Astrid , Dintsis Orfeas , Neiss Andrea , Brunner Michael
Published: December 2008

The Neurospora clock protein FREQUENCY (FRQ) inhibits its transcriptional activator WHITE COLLAR COMPLEX (WCC) in a negative feedback loop and supports its accumulation in a positive loop. We show that positive feedback is a delayed effect of negative feedback underlying the same post-translational mechanisms: DNA-binding-competent active WCC commits rapidly to degradation. FRQ-dependent phosphorylation of WCC, which interferes with DNA binding (negative feedback), leads to reduced turnover and slow accumulation of newly expressed WCC (positive feedback). When DNA binding of WCC is compromised by mutation, its accumulation is independent of FRQ. Cycles of FRQ-dependent inactivation and PP2A-dependent reactivation of WCC occur in the minute range and are coupled to obligate rapid cycles of nucleo–cytoplasmic shuttling. WCC shuttling and activity cycles are modulated by FRQ in circadian fashion.
A high-density SNP-based linkage map of the chicken genome reveals sequence features correlated with recombination rate
Authors: Groenen Martien A.M. , Wahlberg Per , Foglio Mario , Cheng Hans H. , Megens Hendrik-Jan , Crooijmans Richard P.M.A. , Besnier Francois , Lathrop Mark , Muir William M. , Wong Gane Ka-Shu , Gut Ivo , Andersson Leif
Published: December 2008

The resolution of the chicken consensus linkage map has been dramatically improved in this study by genotyping 12,945 single nucleotide polymorphisms (SNPs) on three existing mapping populations in chicken: the Wageningen (WU), East Lansing (EL), and Uppsala (UPP) mapping populations. As many as 8599 SNPs could be included, bringing the total number of markers in the current consensus linkage map to 9268. The total length of the sex average map is 3228 cM, considerably smaller than previous estimates using the WU and EL populations, reflecting the higher quality of the new map. The current map consists of 34 linkage groups and covers at least 29 of the 38 autosomes. Sex-specific analysis and comparisons of the maps based on the three individual populations showed prominent heterogeneity in recombination rates between populations, but no significant heterogeneity between sexes. The recombination rates in the F1 Red Jungle fowl/White Leghorn males and females were significantly lower compared with those in the WU broiler population, consistent with a higher recombination rate in purebred domestic animals under strong artificial selection. The recombination rate varied considerably among chromosomes as well as along individual chromosomes. An analysis of the sequence composition at recombination hot and cold spots revealed a strong positive correlation between GC-rich sequences and high recombination rates. The GC-rich cohesin binding sites in particular stood out from other GC-rich sequences with a 3.4-fold higher density at recombination hot spots versus cold spots, suggesting a functional relationship between recombination frequency and cohesin binding.
Genome-wide profiling of salt fractions maps physical properties of chromatin
Authors: Henikoff Steven , Henikoff Jorja G. , Sakai Akiko , Loeb Gabriel B. , Ahmad Kami
Published: December 2008

We applied genome-wide profiling to successive salt-extracted fractions of micrococcal nuclease-treated Drosophila chromatin. Chromatin fractions extracted with 80 mM or 150 mM NaCl after digestion contain predominantly mononucleosomes and represent classical “active” chromatin. Profiles of these low-salt soluble fractions display phased nucleosomes over transcriptionally active genes that are locally depleted of histone H3.3 and correspond closely to profiles of histone H2Av (H2A.Z) and RNA polymerase II. This correspondence suggests that transcription can result in loss of H3.3+H2Av nucleosomes and generate low-salt soluble nucleosomes. Nearly quantitative recovery of chromatin is obtained with 600 mM NaCl; however, the remaining insoluble chromatin is enriched in actively transcribed regions. Salt-insoluble chromatin likely represents oligonucleosomes that are attached to large protein complexes. Both low-salt extracted and insoluble chromatin are rich in sequences that correspond to epigenetic regulatory elements genome-wide. The presence of active chromatin at both extremes of salt solubility suggests that these salt fractions capture bound and unbound intermediates in active processes, thus providing a simple, powerful strategy for mapping epigenome dynamics.
Histone H2B Deubiquitination Is Required for Transcriptional Activation of FLOWERING LOCUS C and for Proper Control of Flowering in Arabidopsis
Authors: Schmitz Robert Jeffrey , Tamada Yosuke , Doyle Mark Robert , Zhang Xiaoyu , Amasino Richard Mark
Published: December 2008

The spectrum of histone modifications at a given locus is a critical determinant for the correct output of gene expression. In Arabidopsis (Arabidopsis thaliana), many studies have examined the relationship between histone methylation and gene expression, but few studies exist on the relationship between other covalent histone modifications and gene expression. In this work, we describe the role of histone H2B deubiquitination in the activation of gene expression and the consequence of a perturbation of histone H2B deubiquitination in the timing of the floral transition in Arabidopsis. A mutation in a H2B deubiquitinase, UBIQUITIN-SPECIFIC PROTEASE26 (UBP26), results in an early-flowering phenotype. In the ubp26 mutant, mRNA levels of the floral repressor FLOWERING LOCUS C (FLC) and other related family members is decreased. Furthermore, this mutant accumulates H2B monoubiquitination, and has decreased levels of H3K36 trimethylation and increased levels of H3K27 trimethylation at the FLC locus. Thus, UBP26 is required for transcriptional activation of FLC through H2B deubiquitination and is consistent with a model in which deubiquitination is necessary for the accumulation of H3K36 trimethylation and the proper level of transcriptional activation.
Risk, resilience, and natural recovery: a model of recovery from alcohol abuse for Alaska Natives
Authors: Mohatt Gerald V. , Rasmus Stacy M. , Thomas Lisa , Allen James , Hazel Kelly , Marlatt G. Alan
Published: December 2008

Aim  The People Awakening (PA) study explored an Alaska Native (AN) understanding of the recovery process from alcohol abuse and consequent sobriety.

Design  PA utilized a cross‐sectional, qualitative research design and community‐based participatory research methods.

Setting and participants  The study included a state‐wide convenience sample of 57 participants representing all five major AN groups: Aleut/Alutiiq, Athabascan, Inupiaq, Yup'ik/Cup'ik and Tlingit/Haida/Tsimshian. Participants were nominated and self‐identified as being alcohol‐abstinent at least five years following a period of problem drinking.

Measurements  Open‐ended and semistructured interviews gathered extensive personal life histories. A team of university and community co‐researchers analyzed narratives using grounded theory and consensual data analysis techniques.

Findings  A heuristic model of AN recovery derived from our participants' experiences describes recovery as a development process understood through five interrelated sequences: (i) the person entered into a reflective process of continually thinking over the consequences of his/her alcohol abuse; (ii) that led to periods of experimenting with sobriety, typically, but not always, followed by repeated cycling through return to drinking, thinking it over, and experimenting with sobriety; culminating in (iii) a turning point, marked by the final decision to become sober. Subsequently, participants engaged in (iv) Stage 1 sobriety, active coping with craving and urges to drink followed for some participants, but not all, by (v) Stage 2 sobriety, moving beyond coping to what one participant characterized as ‘living life as it was meant to be lived.

Conclusions  The PA heuristic model points to important cultural elements in AN conceptualizations of recovery.
Effectiveness of ozone against endodontopathogenic microorganisms in a root canal biofilm model
Authors: Huth K. C. , Quirling M. , Maier S. , Kamereck K. , AlKhayer M. , Paschos E. , Welsch U. , Miethke T. , Brand K. , Hickel R.
Published: December 2008

Aim  To assess the antimicrobial efficacy of aqueous (1.25–20 μg mL−1) and gaseous ozone (1–53 g m−3) as an alternative antiseptic against endodontic pathogens in suspension and a biofilm model.

Methodology  Enterococcus faecalis, Candida albicans, Peptostreptococcus micros and Pseudomonas aeruginosa were grown in planctonic culture or in mono‐species biofilms in root canals for 3 weeks. Cultures were exposed to ozone, sodium hypochlorite (NaOCl; 5.25%, 2.25%), chlorhexidine digluconate (CHX; 2%), hydrogen peroxide (H2O2; 3%) and phosphate buffered saline (control) for 1 min and the remaining colony forming units counted. Ozone gas was applied to the biofilms in two experimental settings, resembling canal areas either difficult (setting 1) or easy (setting 2) to reach. Time‐course experiments up to 10 min were included. To compare the tested samples, data were analysed by one‐way anova.

Results  Concentrations of gaseous ozone down to 1 g m−3 almost and aqueous ozone down to 5 μg mL−1 completely eliminated the suspended microorganisms as did NaOCl and CHX. Hydrogen peroxide and lower aqueous ozone concentrations were less effective. Aqueous and gaseous ozone were dose‐ and strain‐dependently effective against the biofilm microorganisms. Total elimination was achieved by high‐concentrated ozone gas (setting 2) and by NaOCl after 1 min or a lower gas concentration (4 g m−3) after at least 2.5 min. High‐concentrated aqueous ozone (20 μg mL−1) and CHX almost completely eliminated the biofilm cells, whilst H2O2 was less effective.

Conclusion  High‐concentrated gaseous and aqueous ozone was dose‐, strain‐ and time‐dependently effective against the tested microorganisms in suspension and the biofilm test model.
Benefits of fixed‐dose combination therapy with inhaled corticosteroids and long‐acting bronchodilators as initial maintenance therapy in the management of asthma
Authors: SEALE J. Paul , JENKINS Christine , WOOD‐BAKER Richard , NEVILLE A. Munro
Published: December 2008

Background and objective:  Revised Australian guidelines for asthma management were released by the National Asthma Council (NAC) in 2006. One area where clinical opinion and trial data have changed recently concerns the place of fixed‐dose combination (FDC) therapy with inhaled corticosteroid (ICS) and long‐acting β2‐agonists as initial maintenance therapy.

Methods:  A systematic review of the literature commissioned by the NAC and undertaken by the University of Tasmania addressed several questions, including whether there was evidence for the use of FDC therapy as first‐line asthma treatment in steroid‐naïve patients.

Results:  Nineteen relevant studies were identified, from which 20 comparisons contributed to the analyses. The definition of steroid‐naïve ranged from no ICS therapy over the preceding 1 month to no ICS therapy ever. FDC therapy was effective in subjects who were steroid‐naïve and was more effective than an equivalent dose of ICS, irrespective of the definition of steroid‐naïvety. Compared with ICS alone, FDC therapy increased mean FEV1 by 140 mL, mean morning PEF by 21 L/min and mean evening PEF by 20 L/min. There was a mean increase of 9.8% in symptom‐free days, associated with a greater reduction in rescue medication use of −0.12 puff/24 h. FDC therapy was not superior to ICS alone for prevention of withdrawals or exacerbations requiring systemic corticosteroids. Adverse events were similar for FDC therapy and ICS, whether ICS were administered at the same or an increased dose.

Conclusions:  FDC therapy is effective as first‐line treatment in steroid‐naïve subjects and is superior to ICS alone for most outcomes, irrespective of the period of time since last exposure to ICS.
Brain oscillations forever – neurophysiology in future research of child psychiatric problems
Authors: Rothenberger Aribert
Published: December 2008

For decades neurophysiology has successfully contributed to research and clinical care in child psychiatry. Recently, methodological progress has led to a revival of interest in brain oscillations (i.e., a band of periodic neuronal frequencies with a wave‐duration from milliseconds to several seconds which may code and decode information). These oscillations will nurture future information processing research during normal and pathological brain development, allowing us to investigate basic neuronal connectivity as well as interactions of brain systems and their modulation (e.g., by temporal neuronal synchronisation) as close correlates of behaviour and intermediate phenotypes from genes to behavioural variations. Especially, a systematic neurodynamic look at transitional processes from rest to stimulus‐triggered goal‐directed performance will aid behavioural understanding and guidance of children. Preliminary data suggest two separate oscillatory mechanisms in this respect. One is ongoing from pre‐ to post‐stimulus processing and related to quantitative modification of behaviour, while another is merely related to qualitative effects of behaviour and reflects ‘on‐top’ post‐stimulus processing by temporal neuronal synchronisation of the oscillatory network in question. Suggested neurodynamic models may be tested in multilevel clinical experiments as well as in the framework of computational neuropsychiatry.
Martensite and Reverse Transformation during Complete Cycle of Simple Shear of NiTi Shape Memory Alloy
Authors: Pieczyska E. A. , Gadaj S. P. , Luckner J. , Nowacki W. K. , Tobushi H.
Published: December 2008

Abstract:  Investigation into the quasi‐static simple shear of shape memory alloy (SMA) was carried out. A special grip was designed which allowed replacing compression into the shear process on testing machine. At the same time the shear zone temperature was observed by an infrared camera. The mechanical and thermal characteristics of sheet specimens of NiTi subjected to superelastic shear deformation due to reversible stress‐induced phase transformation were clarified. By comparison of the data, the processes of martensite and reverse transformations during the shear deformation were analysed. The investigation shows that stages of the phase transformations during the simple shear process are similar like those observed during tension test. Moreover, during the simple shear deformation no uniform temperature distributions were noticed, especially at higher shear rate, manifesting that the stress‐induced phase transformation during the shear process is also inhomogeneous. The thermomechanical properties of the NiTi SMA for various shear rates were investigated. It was found that an increase in the strain rate results in an increase in temperature variation, the shear stresses and the magnitude of hysteresis loops between the forward and reverse transformations.
Impact of Performance Obstacles on Intensive Care Nurses' Workload, Perceived Quality and Safety of Care, and Quality of Working Life
Authors: Gurses Ayse P. , Carayon Pascale , Wall Melanie
Published: December 2008

Objectives. To study the impact of performance obstacles on intensive care nurses' workload, quality and safety of care, and quality of working life (QWL). Performance obstacles are factors that hinder nurses' capacity to perform their job and that are closely associated with their immediate work system.

Data Sources/Study Setting. Data were collected from 265 nurses in 17 intensive care units (ICUs) between February and August 2004 via a structured questionnaire, yielding a response rate of 80 percent.

Study Design. A cross‐sectional study design was used. Data were analyzed by correlation analyses and structural equation modeling.

Principal Findings. Performance obstacles were found to affect perceived quality and safety of care and QWL of ICU nurses. Workload mediated the impact of performance obstacles with the exception of equipment‐related issues on perceived quality and safety of care as well as QWL.

Conclusions. Performance obstacles in ICUs are a major determinant of nursing workload, perceived quality and safety of care, and QWL. In general, performance obstacles increase nursing workload, which in turn negatively affect perceived quality and safety of care and QWL. Redesigning the ICU work system to reduce performance obstacles may improve nurses' work.
Role of Crab Herbivory in Die‐Off of New England Salt Marshes
Authors: HOLDREDGE CHRISTINE , BERTNESS MARK D. , ALTIERI ANDREW H.
Published: December 2008

Abstract:  Die‐offs of cordgrass are pervasive throughout western Atlantic salt marshes, yet understanding of the mechanisms precipitating these events is limited. We tested whether herbivory by the native crab, Sesarma reticulatum, is generating die‐offs of cordgrass that are currently occurring on Cape Cod, Massachusetts (U.S.A.), by manipulating crab access to cordgrass transplanted into die‐off areas and healthy vegetation. We surveyed 12 Cape Cod marshes to investigate whether the extent of cordgrass die‐off on creek banks, where die‐offs are concentrated, was related to local Sesarma grazing intensity and crab density. We then used archived aerial images to examine whether creek bank die‐off areas have expanded over the past 2 decades and tested the hypothesis that release from predation, leading to elevated Sesarma densities, is triggering cordgrass die‐offs by tethering crabs where die‐offs are pervasive and where die‐offs have not yet been reported. Intensity of crab grazing on transplanted cordgrass was an order of magnitude higher in die‐off areas than in adjacent vegetation. Surveys revealed that Sesarma herbivory has denuded nearly half the creek banks in Cape Cod marshes, and differences in crab‐grazing intensity among marshes explained >80% of variation in the extent of the die‐offs. Moreover, the rate of die‐off expansion and area of marsh affected have more than doubled since 2000. Crab‐tethering experiments suggest that release from predation has triggered elevated crab densities that are driving these die‐offs, indicating that disruption of predator–prey interactions may be generating the collapse of marsh ecosystems previously thought to be exclusively under bottom‐up control.
Abrupt Termination of an Ethanol Regimen Provokes Ventricular Arrhythmia and Enhances Susceptibility to the Arrhythmogenic Effects of Epinephrine in Rats
Authors: Liu Jinyao , Fujimiya Tatsuya
Published: December 2008

Background: Pathologists examining victims of sudden unexpected death encounter alcoholics more often than expected; alcohol may play a role in sudden arrhythmic death. Here we determine whether a pattern of alcohol consumption, chronic ethanol intake, and withdrawal increases the incidence of malignant ventricular arrhythmia and modulates susceptibility to the arrhythmogenic potential of sympathetic stimulation from an epinephrine test in rats.

Methods: Male Wistar rats were treated with a continuous ethanol liquid diet for 7 weeks, and then subjected to 1‐day withdrawal or 21‐day abstinence. Ventricular ectopy was evaluated by 24‐hour electrocardiographic telemetry recording; whole‐body sympathetic activation, cardiac sympathovagal balance, and susceptibility to ventricular arrhythmia induced by sympathetic stimulation were evaluated based on blood noradrenalin metabolite concentrations, heart rate variability, and a 3‐step epinephrine test.

Results: Ventricular arrhythmia and related death were observed only in rats at 1 day of withdrawal, but not in nonalcoholic, continuous ethanol intake or 21‐day abstinence rats. One‐day withdrawal after a 7‐week continuous ethanol regimen elevated circulating noradrenalin metabolite levels and induced cardiac sympathovagal imbalance. Deaths related to the epinephrine test and ventricular arrhythmia induced by low doses of epinephrine were observed only in 1‐day withdrawal rats. However, all anomalies were normalized by 21‐day abstinence.

Conclusions: Abrupt termination of a 7‐week continuous ethanol regimen is sufficient to enhance the whole‐body sympathetic activation and cardiac sympathovagal imbalance that contribute to ventricular arrhythmia and sudden death in alcoholic rats. Those providing medical care for alcoholics, including in cases of legal imprisonment, should be aware of the possibility of enhanced susceptibility to sudden arrhythmic death due to the abrupt termination of a chronic ethanol regimen.
A Product‐Level Approach to Historical Material Flow Analysis
Authors: Harper Ermelinda M.
Published: December 2008

Studies of material cycles, which have a solid history in biogeochemistry, include characterization of technological materials cycles that quantify the way in which materials move through the economy and environment of a region. One of the most important aspects of historical technological materials cycles is determining how much material goes into various uses over time and modeling its lifetime in each use. A material flow analysis methodology is presented by which a historical (i.e., 1975 to 2000) study of tungsten use in the United States was constructed. The approach utilized in this study is twofold: the traditional approach by which material going into end‐use sectors is approximated (the “end‐use sector model”), and a second approach by which end‐use products are specifically addressed (the “finished product model”). By virtue of the latter method, a detailed historical account of a material's end uses was developed. This study shows that (1) both models present a detailed treatment of trade of finished products over time for a variety of highly disaggregated products, (2) the end‐use sector model provides a method to combine quantitative and qualitative data about products in various sectors to estimate domestic production for a metal about which little is known in terms of its end uses, and (3) the finished product model produces detailed estimates of domestic production for a large number of highly disaggregated products.
The role of CCAAT/enhancer binding protein (C/EBP)‐α in osteogenesis of C3H10T1/2 cells induced by BMP‐2
Authors: Fan Qiming , Tang Tingting , Zhang Xiaoling , Dai Kerong
Published: December 2008

The balance between osteogenesis and adipogenesis of mesenchymal stem cells is disrupted in various human diseases. Investigating the mechanisms that fine‐tune this balance is of medical importance. Identification of potential target gene which can be used to study the relationship between them could be really helpful for this purpose. In the current study, we used C3H10T1/2 as model cells and through which two models of both osteogenesis induced by bone‐morphogenetic protein (BMP)‐2 and transdifferentiation from osteogenesis to adipogenesis were established. We investigated the role of CCAAT/enhancer binding protein (C/EBP)‐α in these two systems. Then from epigenetic point of view, we elucidated the underlying molecular mechanisms preliminarily. The results showed that down‐regulations of both C/EBP‐α expression and its inducibility in response to insulin, fetal bovine serum, methylisobutylxanthine and dexamethasone (IFMD) adipogenic hormonal cocktail were observed in terminal stage of osteogenesis of C3H10T1/2 cells induced by BMP‐2. And overexpression of C/EBP‐α could lead to inhibition of osteogenesis differentiation and rescue attenuation of potential of adipogenic conversion in this process. Furthermore, we provided evidence that remarkable DNA hypermethylation and histones 3 and 4 hypoacetylation in –1286 bp/−1065 bp promoter region of C/EBP‐α were involved in both of down‐regulations. Our data suggest that C/EBP‐α functions as regulator in the balance between osteogenesis and adipogenesis of C3H10T1/2 cells and may be a therapeutic target.
Beyond Westminster governance: Bringing politics and public service into the networked era
Authors: Roy Jeffrey
Published: December 2008

Abstract: The underlying premise of this article stems from the following question: is our Westminster, parliamentary model of democratic governance and administration adaptable for contemporary realities and emerging challenges? By way of response, the author attempts to expose what is wrong with the current model and sketches what changes to our governing institutions must be envisioned in order to safeguard political legitimacy and administrative competence in a world that is increasingly networked. Central to this discussion is the doctrine of ministerial responsibility and accountability and an appropriate parcelling of roles and authorities to public servants and politicians. Equally important is the rise of the Internet and new forms of political mobilization outside of government, on the one hand, and the potential for more direct mechanisms of public engagement, on the other hand. Without significant innovation and reform, Parliament and the federal government instead face a steady erosion of political and human capital that cannot be reversed until the country is convinced that 1) a new approach to governing is a realistic proposition, and 2) citizens will play an important role in designing this new approach.

Sommaire: La prémisse sous‐jacente du présent article découle de la question suivante : est‐ce que notre modèle de Westminster de gouvernance et d'administration démocratique parlementaire peut s'adapter aux réalités contemporaines et aux défis émergents? En guise de réponse, l'article essaie d'exposer ce qui ne ne fonctionne pas dans le modèle actuel et donne un aperçu du genre de changements que nous devons envisager pour nos institutions dirigeantes afin de sauvegarder la légitimité politique et la compétence administrative dans un monde de plus en plus réseauté. Au centre de cette discussion se trouvent la doctrine de la responsabilité et de l'imputabilité ministérielle et une répartition appropriée des rôles et des pouvoirs des fonctionnaires et des responsables politiques. Tout aussi importants sont le rôle accru d'Internet et de nouvelles formes de mobilisation politique en dehors du gouvernement d'une part, et la possibilité de recourir à des mécanismes de participation publique plus directe, d'autre part. Par contre, à défaut d'innovations et de réformes importantes, le Parlement et le gouvernement fédéral font face à une érosion continue du capital politique et humain qui ne peut être inversée tant que le pays ne sera pas convaincu : a) qu'une nouvelle manière de gouverner est une proposition réaliste; et b) que les citoyens joueront un rôle important en concevant cette nouvelle démarche.
Les relations de collaboration entre le secteur public et les organismes communautaires du secteur jeunesse‐enfance‐famille : Entre la sous‐traitance et la coconstruction
Authors: Savard Sébastien , Harvey Benoît , Tremblay Sabrina
Published: December 2008

Sommaire: L'État incite les établissements publics et les organismes communautaires à développer et à augmenter la fréquence de leurs relations interorganisationnelles. L'État veut ainsi favoriser une intégration des services permettant une meilleure réponse aux besoins sociaux de la population. Cette étude propose une typologie permettant d'analyser les modèles de relation qui se mettent en place entre ces deux groupes d'acteurs. La recherche s'est intéressée aux interfaces dans le secteur des services sociaux à l'enfance, à la jeunesse et aux familles québécoises. Au total, 111 gestionnaires ont répondu à un questionnaire leur permettant d'évaluer leurs rapports en fonction de quatre dimensions proposées par Coston pour situer les relations entre l'État et les organismes du tiers secteur. Le modèle de relation rapporté par les répondants est celui de la coexistence. Quoique le modèle de relation rapporté par les organismes communautaires et par les établissements publics soit le même, une analyse plus nuancée des résultats permet de constater que les organismes communautaires se perçoivent appartenir à un système plus socio‐étatique (dominé par les établissements de réseau) que les répondants des établissements publics.

Abstract: The government encourages public institutions and community organizations to develop and increase the frequency of their inter‐organizational relationships. In doing so, the government seeks the integration of their services in order to meet the social needs of the population more effectively. This study aims to develop a typology for analysing patterns in the relationships being established between these two groups of stakeholders. The research focused on the interfaces in the social service sector for children, youth and families in Quebec. In total, 111 managers responded to a survey that enabled them to assess their relationships on the basis of four dimensions proposed by Coston for analysing relationships between the government and third‐sector organizations. The respondents identified “coexistence” as the most common type of relationships. Although the community organizations and the public institutions identified the same type of relationships, a more nuanced analysis of the survey results reveals that community organizations see themselves as part of a system that is more “socio‐governmental” in nature (i.e., dominated by the institutions in the network) rather than “public.”
A Locking Compliant Device Inspired by the Anatomy of the Spine
Authors: Kern Nicole I. , Majewski Thomas J. , Triolo Ronald J. , Kobetic Rudi , Quinn Roger D.
Published: December 2008

A device reminiscent of the mammalian spine has been designed and built with the ability to lock each individual joint in a string of ball joints. The assembly may be controlled in a manner similar to other hyper-redundant robots, with the added advantage of locking in a straight or axial position. Locking is achieved by orienting two mating collars in a singular configuration that forces compression against neighboring collars and prohibits bending or rotation. Locking is desirable for added strength in supporting objects, as well as for stabilization and power efficiency when bending is not necessary. The split locking mechanism represents a biologically inspired structure with added strength and stability for use in robotics.
A Coaxial Tube Model of the Cerebrospinal Fluid Pulse Propagation in the Spinal Column
Authors: Cirovic Srdjan
Published: December 2008

The dynamics of the movement of the cerebrospinal fluid (CSF) may play an important role in the genesis of pathological neurological conditions such as syringomyelia, which is characterized by the presence of a cyst (syrinx) in the spinal cord. In order to provide sound theoretical grounds for the hypotheses that attribute the formation and growth of the syrinx to impediments to the normal movement of the CSF, it is necessary to understand various modes through which CSF pulse in the spinal column propagates. Analytical models of small-amplitude wave propagation in fluid-filled coaxial tubes, where the outer tube represents dura, the inner tube represents the spinal cord, and the fluid is the CSF, have been used to that end. However, so far, the tendency was to model one of the two tubes as rigid and to neglect the effect of finite thickness of the tube walls. The aim of this study is to extend the analysis in order to address these two potentially important issues. To that end, classical linear small-amplitude analysis of wave propagation was applied to a system consisting of coaxial tubes of finite thickness filled with inviscid incompressible fluid. General solutions to the governing equations for the case of harmonic waves in the long wave limit were replaced with the boundary conditions to yield the characteristic (dispersion) equation for the system. The four roots of the characteristic equation correspond to four modes of wave propagation, of which the first three are associated with significant motion of the CSF. For the normal range of parameters the speeds of the four modes are c1=13m∕s, c2=14.7m∕s, c3=30.3m∕s, and c4=124.5m∕s, which are well within the range of values previously reported in experimental and theoretical studies. The modes with the highest and the lowest speeds of propagation can be attributed to the dura and the spinal cord, respectively, whereas the remaining two modes involve some degree of coupling between the two. When the thickness of the spinal cord, is reduced below its normal value, the first mode becomes dominant in terms of the movement of the CSF, and its speed drops significantly. This suggests that the syrinx may be characterized by an abnormally low speed of the CSF pulse.
Load Transfer Mechanism for Different Metatarsal Geometries: A Finite Element Study
Authors: García-Aznar J. M. , Bayod J. , Rosas A. , Larrainzar R. , García-Bógalo R. , Doblaré M. , Llanos L. F.
Published: December 2008

The load transfer mechanism across the skeleton of the human foot is very important to understand its biomechanical function. In this work, we develop several computational models to compare the biomechanical response of different metatarsal geometries. Finite element 3D simulations of feet reconstructed from computer tomography (CT) scans were used to evaluate the stress/strain distributions during the stance posture. The numerical predictions for pathological and healthy foot geometries present different load transfer mechanisms that can provide a biomechanical explanation of why some metatarsal geometrical configurations cause different foot skeletal stresses. The most significant result in all cases was a reduction between 20% and 30% of the peak load supported by the first metatarsal. Therefore, we conclude that a clearly unloaded first metatarsal, overloading the rest, is a risk factor to induce metatarsalgia.
A Short Note on Transverse Vibrations of a Shaft Carrying Two (or One) Disk Excited by a Nonideal Motor
Authors: Felix J. L. Palacios , Balthazar J. M. , Brasil R. M. L. R. F.
Published: December 2008

The paper presents a number of numerical simulations of the transverse vibrations of two (or one) unbalanced rotors forced by an electric motor, with limited power supply, during the passage through of the two resonance zones (increasing and decreasing input voltages). The predominant presence of the Sommerfeld effect, when the rotational velocity of the motor is captured, in the second resonance frequency is demonstrated. We have shown that the hysteretic jump phenomenon exists in a rotor system with two (or one) disks, and with this, we have shown that a torque is influenced by the dynamical behavior of the rotor.
Evolutionary Multi-Agent Systems: An Adaptive and Dynamic Approach to Optimization
Authors: Hanna Lindsay , Cagan Jonathan
Published: December 2008

This paper explores the ability of a virtual team of specialized strategic software agents to cooperate and evolve to adaptively search an optimization design space. Our goal is to demonstrate and understand how such dynamically evolving teams may search more effectively than any single agent or a priori set strategy. We present a core framework and methodology that has potential applications in layout, scheduling, manufacturing, and other engineering design areas. The communal agent team organizational structure employed allows cooperation of agents through the products of their work and creates an ever changing set of individual solutions for the agents to work on. In addition, the organizational structure allows the framework to be adaptive to changes in the design space that may occur during the optimization process. An evolutionary approach is used, but evolution occurs at the strategic rather than the solution level, where the strategies of agents in the team are the decisions for when and how to choose and alter a solution, and the agents evolve over time. As an application of this approach in a static domain, individual solutions are tours in the familiar combinatorial optimization problem of the traveling salesman. With a constantly changing set of these tours, the team, with each agent employing a different solution strategy, must evolve to apply the solution strategies, which are most useful given the solution set at any point in the process. We discuss the extensions to our preliminary work that will make our framework useful to the design and optimization community.