bluuebunny/crossref_metadata_2025 huggingface dataset:
Sign changes and resonance of intrinsic spin Hall effect in two-dimensional hole gas
Authors: Ma Tianxing , Liu Qin
Published: September 2006

The intrinsic spin Hall conductance shows rich sign changes by applying a perpendicular magnetic field in two-dimensional hole gas. Especially, notable sign changes can be achieved by adjusting the characteristic length of the Rashba coupling and hole density at moderate magnetic fields. The resonant intrinsic spin Hall conductance appears in high hole density and strong magnetic field due to the transition between mostly spin −12 holes and spin 32 holes is confirmed. Two likely ways to establish intrinsic spin Hall effect in experiments and a possible application are suggested.
Zero-gravity liquid-vapor interfaces in circular cylinders
Authors: Collicott Steven H. , Lindsley William G. , Frazer David G.
Published: September 2006

The zero-gravity problems of a liquid volume sealing a circular tube of gas and a gaseous volume in a circular tube of liquid both involve one phase obstructing another. The two problems differ only in contact angle. From pulmonary research there is a history of axisymmetric analyses for liquid droplets in circular tubes of gas. These analyses consider only axisymmetric solutions—an annulus and an axisymmetric plug. Only recently have nonsymmetric solutions for nonzero contact angle wetting liquids (0°–90° contact angle) been realized by the authors with the use of the Surface Evolver code. Similar to the problem of droplets in a gas filled tube, a bubble in a liquid-filled tube is of interest to the commercial satellite industry and in vascular physiology. Further analysis by the authors now fills in the other half of contact angle range, i.e., either a nonwetting liquid in a tube of gas (contact angles of 90°–180°), or equivalently, a gaseous bubble in a liquid that wets the tube wall. Conditions for the existence and stability of solutions of three topologies are examined.
Inertia-induced coherent structures in a time-periodic viscous mixing flow
Authors: Speetjens M. F. M. , Clercx H. J. H. , van Heijst G. J. F.
Published: September 2006

Inertia-induced changes in transport properties of an incompressible viscous time-periodic flow due to fluid inertia (nonzero Reynolds numbers Re) are studied in terms of the topological properties of volume-preserving maps. In the noninertial Stokes limit (vanishing Re), the flow relates to a so-called one-action map. However, the corresponding invariant surfaces are topologically equivalent to spheres rather than the common case of tori. This has fundamental ramifications for the response to small departures from the noninertial limit and leads to a new type of response scenario: resonance-induced merger of coherent structures. Thus several coexisting families of two-dimensional coherent structures are formed that make up two classes: fully closed structures and leaky structures. Fully closed structures restrict motion as in a one-action map; leaky structures have open boundaries that connect with a locally chaotic region through which exchange of material with other leaky structures occurs. For large departures from the noninertial limit the above structures vanish and the topology becomes determined by isolated periodic points and associated manifolds. This results in unrestricted chaotic motion.
Improvement in the reduction of silver ions in aqueous solution using two-photon sensitive dye
Authors: Ishikawa Atsushi , Tanaka Takuo , Kawata Satoshi
Published: September 2006

The reduction properties of silver ions in aqueous solution were improved with a two-photon sensitive dye. Excitation of the dye through a two-photon absorption process allowed a low laser power to trigger the reduction of silver ions, and sub-diffraction-limit fabrication was realized. An electrically conductive silver wire with a minimum width of 400nm was achieved. The authors also demonstrated the fabrication of self-standing three-dimensional silver microstructures with arbitrary shapes on a glass substrate.
Multilayer exchange spring media for magnetic recording
Authors: Suess D.
Published: September 2006

The concept of exchange spring media is extended from two layers to N layers. The coercive field of the multilayer structure decreases with 1∕N while the energy barrier is only determined by the magnetic properties of the hardest layer. A 25nm thick trilayer has a 7.5 times smaller coercive field (1.4T) as a single layer at the same thermal stability and for the same value of the magnetization. A continuous variation of the anisotropy in the recording media reduces the coercive field by a factor of 10 for a layer thickness of 25nm.
Vlasov simulation of amplitude-modulated Langmuir waves
Authors: Umeda Takayuki
Published: September 2006

Mechanisms for the generation of Langmuir wave packets are studied by performing a one-dimensional electrostatic Vlasov simulation. The present simulation of a weak-electron-beam instability without ion dynamics suggests two new processes for the amplitude modulation of Langmuir waves. The beam instability excites Langmuir modes over a wide wave number range, but the saturation of the most unstable Langmuir mode “filters” the growth of sideband modes. Specific upper and lower sideband modes linearly grow to a high saturation level. Then the primary Langmuir mode is amplified and strongly modulated through interaction with the sideband modes.
Single electron dynamics in a quantum dot field effect transistor
Authors: Kardynał B. E. , Shields A. J. , Farrer I. , Cooper K. , Ritchie D. A.
Published: September 2006

The authors show that in a quantum dot field single photon detector it is possible to reduce the duration of the single photon induced signal to allow continuous operation of the detector. By reducing the charge trapped in a dot by one electron with a single photohole and measuring the subsequent recapture time, we find that the latter depends only on the electron population of the channel of the transistor. It can be tuned in a single device from tens of microseconds to less than 200ns, which is the limit of their measurement setup.
Effects of edge dislocations and intentional Si doping on the electron mobility of n-type GaN films
Authors: Zhao D. G. , Yang Hui , Zhu J. J. , Jiang D. S. , Liu Z. S. , Zhang S. M. , Wang Y. T. , Liang J. W.
Published: September 2006

The effects of dislocations and Si doping on the electrical properties of n-type GaN grown by metal organic chemical vapor deposition (MOCVD) are investigated. It is found that both electron mobility and carrier concentration are strongly influenced by edge dislocations. A moderate Si doping during the GaN growth improves the electron mobility, but the best doping effect depends on the dislocation density of the sample. High quality about 4-μm-thick MOCVD-grown GaN film with a room temperature electron mobility as high as 1005cm2∕Vs is obtained by optimizing growth conditions.
Determination of the concentration of recombination centers in thin asymmetrical p-n junctions from capacitance transient spectroscopy
Authors: Jiménez Tejada Juan A. , Lara Bullejos Pablo , López Villanueva Juan A. , Gómez-Campos Francisco M. , Rodríguez-Bolívar Salvador , Deen M. Jamal
Published: September 2006

Recombination centers in thin asymmetrical p-n junctions were analyzed in the context of capacitance transient experiments. The combined effect of the thin low-doped region of the junction and the nonzero value of the occupation factor of the recombination center in the depletion layer caused electrons and holes to be simultaneously released from different parts of this layer during an emission transient. The need to introduce modifications in the analytical expressions that determine the parameters of these centers by capacitance transient spectroscopy is demonstrated. A correction formula to determine concentrations of electron or hole traps or recombination centers is proposed.
Binary to unary transition problem in nucleation theory
Authors: Zhuo Lin , Wu David T.
Published: September 2006

The limiting behavior in binary nucleation theory when one component vanishes is examined. Failure of the traditional continuum theory to predict the transition from binary to unary nucleation is due to breakdown of the continuum approximation. A semidiscrete model is constructed for the transition regime. For binary systems of arbitrary composition, a general formula that combines the semi-discrete and continuum nucleation rates is proposed. Comparison with the exact solution calculated using a fully discrete matrix method shows good agreement.
Realization of periodic and quasiperiodic microstructures with sub-diffraction-limit feature sizes by far-field holographic lithography
Authors: Yang Yi , Wang Guo Ping
Published: September 2006

The authors experimentally demonstrate a far-field holography for the realization of Ag nanoparticles-embedded periodic and quasiperiodic microstructures with feature sizes beyond the diffraction limit. Periodic cylindrical nanoshell arrays with about 240nm hole diameter and 12-fold symmetry quasiperiodic structures with 220nm feature sizes are achieved, respectively, by using a 632.8nm laser beam. Our results imply that conventional far-field optical technology is capable of fabricating nanostructures in modern micromanufacture.
Role of fascin in filopodial protrusion
Authors: Vignjevic Danijela , Kojima Shin-ichiro , Aratyn Yvonne , Danciu Oana , Svitkina Tatyana , Borisy Gary G.
Published: September 2006

In this study, the mechanisms of actin-bundling in filopodia were examined. Analysis of cellular localization of known actin cross-linking proteins in mouse melanoma B16F1 cells revealed that fascin was specifically localized along the entire length of all filopodia, whereas other actin cross-linkers were not. RNA interference of fascin reduced the number of filopodia, and remaining filopodia had abnormal morphology with wavy and loosely bundled actin organization. Dephosphorylation of serine 39 likely determined cellular filopodia frequency. The constitutively active fascin mutant S39A increased the number and length of filopodia, whereas the inactive fascin mutant S39E reduced filopodia frequency. Fluorescence recovery after photobleaching of GFP-tagged wild-type and S39A fascin showed that dephosphorylated fascin underwent rapid cycles of association to and dissociation from actin filaments in filopodia, with t1/2 < 10 s. We propose that fascin is a key specific actin cross-linker, providing stiffness for filopodial bundles, and that its dynamic behavior allows for efficient coordination between elongation and bundling of filopodial actin filaments.
The centromere-specific histone variant Cse4p (CENP-A) is essential for functional chromatin architecture at the yeast 2-μm circle partitioning locus and promotes equal plasmid segregation
Authors: Hajra Sujata , Ghosh Santanu Kumar , Jayaram Makkuni
Published: September 2006

The centromere protein A homologue Cse4p is required for kinetochore assembly and faithful chromosome segregation in Saccharomyces cerevisiae. It has been regarded as the exquisite hallmark of centromeric chromatin. We demonstrate that Cse4 resides at the partitioning locus STB of the 2-μm plasmid. Cse4p-STB association is absolutely dependent on the plasmid partitioning proteins Rep1p and Rep2p and the integrity of the mitotic spindle. The kinetochore mutation ndc10-1 excludes Cse4p from centromeres without dislodging it from STB. Cse4p-STB association lasts from G1/S through late telophase during the cell cycle. The release of Cse4p from STB chromatin is likely mediated through spindle disassembly. A lack of functional Cse4p disrupts the remodeling of STB chromatin by the RSC2 complex, negates Rep2p binding and cohesin assembly at STB, and causes plasmid missegregation. Poaching of a specific histone variant by the plasmid to mark its partitioning locus with a centromere tag reveals yet another one of the molecular trickeries it performs for achieving chromosome- like fidelity in segregation.
RLIP76 (RalBP1) is an R-Ras effector that mediates adhesion-dependent Rac activation and cell migration
Authors: Goldfinger Lawrence E. , Ptak Celeste , Jeffery Erin D. , Shabanowitz Jeffrey , Hunt Donald F. , Ginsberg Mark H.
Published: September 2006

The Ras family of small GTPases regulates cell proliferation, spreading, migration and apoptosis, and malignant transformation by binding to several protein effectors. One such GTPase, R-Ras, plays distinct roles in each of these processes, but to date, identified R-Ras effectors were shared with other Ras family members (e.g., H-Ras). We utilized a new database of Ras-interacting proteins to identify RLIP76 (RalBP1) as a novel R-Ras effector. RLIP76 binds directly to R-Ras in a GTP-dependent manner, but does not physically associate with the closely related paralogues H-Ras and Rap1A. RLIP76 is required for adhesion-induced Rac activation and the resulting cell spreading and migration, as well as for the ability of R-Ras to enhance these functions. RLIP76 regulates Rac activity through the adhesion-induced activation of Arf6 GTPase and activation of Arf6 bypasses the requirement for RLIP76 in Rac activation and cell spreading. Thus, we identify a novel R-Ras effector, RLIP76, which links R-Ras to adhesion-induced Rac activation through a GTPase cascade that mediates cell spreading and migration.
Specific and flexible roles of heparan sulfate modifications in Drosophila FGF signaling
Authors: Kamimura Keisuke , Koyama Takashi , Habuchi Hiroko , Ueda Ryu , Masu Masayuki , Kimata Koji , Nakato Hiroshi
Published: September 2006

Specific sulfation sequence of heparan sulfate (HS) contributes to the selective interaction between HS and various proteins in vitro. To clarify the in vivo importance of HS fine structures, we characterized the functions of the Drosophila HS 2-O and 6-O sulfotransferase (Hs2st and Hs6st) genes in FGF-mediated tracheal formation. We found that mutations in Hs2st or Hs6st had unexpectedly little effect on tracheal morphogenesis. Structural analysis of mutant HS revealed not only a loss of corresponding sulfation, but also a compensatory increase of sulfation at other positions, which maintains the level of HS total charge. The restricted phenotypes of Hsst mutants are ascribed to this compensation because FGF signaling is strongly disrupted by Hs2st; Hs6st double mutation, or by overexpression of 6-O sulfatase, an extracellular enzyme which removes 6-O sulfate groups without increasing 2-O sulfation. These findings suggest that the overall sulfation level is more important than strictly defined HS fine structures for FGF signaling in some developmental contexts.
The action behind the words: embryonic stem cell research marches on
Authors: Leslie Mitch
Published: September 2006

Talk of policy has dominated talk of science for those interested in embryonic stem cell science. But research is continuing, and the advances are making clear why embryonic stem cells are such an important scientific and medical resource.
Needle vs surgical cricothyroidotomy: a short cut to effective ventilation
Authors: Scrase I. , Woollard M.
Published: September 2006

Cricothyroidotomy can be performed using three techniques. This literature review seeks to determine which is more appropriate for use in prehospital can't intubate/can't ventilate scenarios where laryngeal mask airways prove ineffective. The common approach of inserting a 14‐gauge cannula and using low‐pressure ventilation via intermittent occlusion of an opening in oxygen tubing (15 l.min−1 flow) results in ineffective ventilation within 60 s or less, depending on the degree of airway obstruction. In the absence of a high degree of upper airway obstruction, ventilation can be effective if the cannula is attached to a high pressure (45 psi) jet ventilator, but such devices are rare in UK prehospital practice. A self‐inflating bag used with a cuffed tube inserted through a horizontal scalpel incision provides sustained adequate ventilation, has a relatively low complication rate compared to needle cricothyroidotomy and is a skill that can be easily taught to paramedics, nurses and doctors.
The history of extracorporeal oxygenators*
Authors: Lim M. W.
Published: September 2006

Extracorporeal oxygenators are artificial devices that substitute for anatomical lungs by delivering oxygen to, and extracting carbon dioxide from, blood. They were first conceptualised by the English scientist Robert Hooke (1635–1703) and developed into practical extracorporeal oxygenators by French and German experimental physiologists in the 19th century. Indeed, most of the extracorporeal oxygenators used until the late 1970s were derived from von Schroder's 1882 bubble oxygenator and Frey and Gruber's 1885 film oxygenator. As there is no intervening barrier between blood and oxygen, these are called ‘direct contact’ oxygenators; they contributed significantly to the development and practice of cardiac surgery till the 1980s. Membrane extracorporeal oxygenators introduce a gas–permeable interface between blood and oxygen. This greatly decreased the blood trauma of direct‐contact extracorporeal oxygenators, and enabled extracorporeal oxygenators to be used in longer‐term applications such as the intensive therapy of respiratory distress syndrome; this was demonstrably beneficial for neonates but less so for older patients. Much work since the 1960s focused on overcoming the gas exchange handicap of the membrane barrier, leading to the development of high‐performance microporous hollow‐fibre oxygenators that eventually replaced direct‐contact oxygenators in cardiac theatres.
An in vitro study of the compliance of paediatric tracheal tube cuffs and tracheal wall pressure
Authors: Bernet V. , Dullenkopf A. , Cannizzaro V. , Stutz K. , Weiss M.
Published: September 2006

Cuff volume‐pressure curves and cuff pressure‐tracheal wall pressure relationships were investigated in eight brands of currently available cuffed, paediatric tracheal tubes with internal diameters of 5.0 mm. Cuff volume‐pressure curves were measured with the cuff unrestricted and with the cuff placed within a tracheal model with wall pressure measurements. With the tracheal tube cuffs, unrestricted cuff compliance at 20 cmH2O cuff pressure varied between 0.06 and 0.3 ml.cmH2O−1. With the cuff restricted within the model trachea, all tracheal tube cuffs became considerably less compliant (0.01–0.09 ml.cmH2O−1). We found tracheal wall pressure was similar to the cuff pressure as long as the resulting cuff diameter was sufficiently large freely to drape the inner tracheal wall. We found that, regardless of whether a higher or lower compliant tube cuff was used, cuff hyperinflation uniformly resulted in potentially compromised tracheal mucosal blood flow; cuff pressure monitoring using cuff pressure limitation is therefore strongly recommended.
Acute peri‐operative beta blockade in intermediate‐risk patients
Authors: Biccard B. M. , Sear J. W. , Foëx P.
Published: September 2006

Peri‐operative beta‐blockade has been shown to reduce the incidence of postoperative cardio‐ vascular complications including cardiac death in high‐risk non‐cardiac surgical patients. However, the recent analysis by Lindenauer et al. suggests that it is inappropriate to administer beta‐blockers blindly to all surgical patients. In an attempt to determine the appropriateness of peri‐operative beta‐blocker administration across patients with a spectrum of cardiovascular risks, we have examined studies of intermediate‐risk patient groups (that is those undergoing intermediate risk surgery or those with a Lee Revised Cardiac Risk Score of≤2). We analysed data from randomised prospective studies of the effects of acute peri‐operative beta‐blockade on the incidence of peri‐operative myocardial ischaemia. By examining the demographics and surgical interventions in these patients, we have compared these studies with other studies of peri‐operative silent myocardial ischaemia representing patients of similar risk. We thus estimated the expected long‐term postoperative cardiovascular complication rate associated with myocardial ischaemia in these patients in terms of number needed to treat for ischaemia prevention and for prevention of major cardiovascular complications. Prevention of peri‐operative myocardial ischaemia with acute beta‐blockade in non‐cardiac surgical patients with 1–2 RCRI clinical risk factors can be achieved with a number needed to treat of 10. It is not associated with a significant increase in drug associated side‐effects. However, acute beta‐blockade shows no real benefit in the prevention of major cardiovascular complications in intermediate risk non‐vascular surgical patients with a number‐needed‐to‐treat of 833. Vascular surgical patients undergoing intermediate‐risk surgery may benefit from the protective effects of acute peri‐operative beta‐blockade, however, with a number‐needed‐to‐treat of 68 it would require a randomised clinical trial of over 24 000 patients to prove their efficacy.
Determination of the optimal angle for needle insertion during caudal block in children using ultrasound imaging
Authors: Park J. H. , Koo B. N. , Kim J. Y. , Cho J. E. , Kim W. O. , Kil H. K.
Published: September 2006

Using ultrasound imaging, the optimal angle for needle insertion during caudal epidural injection in children was estimated. After general anaesthesia, ultrasonography was performed at the sacral hiatus in 130 children aged 2–84 months positioned in the lateral position. The median [range] values for the intercornual, caudal space depth and the distance from skin to the posterior sacral bony surface were 17.0 [9.6–24] mm, 3.5 [1–8] mm and 21.0 [10–39] mm, respectively. The optimal angle showed no significant correlation with age, weight, height or body surface area. The median [range] calculated optimal angle for the needle was 21.0 [10–38]°. We conclude that the needle should be inserted at about 20° to the skin to avoid puncture of the bone and potential intra‐osseous injection.
Use of continuous positive airway pressure during spinal anaesthesia in a patient with severe chronic obstructive pulmonary disease
Authors: Bapat P. P. , Anderson J. A. , Bapat S. , Sule A.
Published: September 2006

We report the case of a patient with severe chronic obstructive pulmonary disease who underwent local resection of a carcinoma of the rectum under spinal anaesthesia. Although the patient was keen to avoid general anaesthesia and to have the operation under a spinal anaesthetic, pre‐operative assessment showed that he could not lie flat. As the surgical procedure required the patient to be in the lithotomy position, ideally with a head‐down tilt, it was hoped that continuous positive airway pressure with a facemask during spinal anaesthesia might help him to tolerate the position comfortably. Continuous positive airway pressure at 7.5 cmH2O was successfully used to facilitate breathing during surgery under spinal anaesthesia. A combination of regional anaesthesia and continuous positive airway pressure via a facemask is easy to use and may be a useful option in the management of these challenging patients.
A human monoclonal antiprothrombin antibody is thrombogenic in vivo and upregulates expression of tissue factor and E‐selectin on endothelial cells
Authors: Vega‐Ostertag Mariano , Liu Xiaowei , Kwan‐Ki Hwang , Chen Pojen , Pierangeli Silvia
Published: September 2006

Prothrombin is now accepted as one of the target antigens recognised by antiphospholipid (aPL) antibodies. However, it is not clear whether anti‐prothrombin antibodies are pathogenic in vivo and if so, the possible mechanism(s) involved. Here, we examined the pathogenic effects of the IS6 monoclonal anti‐prothrombin antibody isolated from a patient with Antiphospholipid Syndrome (APS). IS6 antibody was purified from hybridoma supernatant. Its pathogenic potentials were studied in an in vivo model of induced thrombosis. The expression of tissue factor (TF) and E‐selectin on human umbilical vein endothelial cells (HUVEC) was determined by cyto‐enzyme‐linked immunosorbent assay. Transcription of TF mRNA was determined by quantitative real time‐polymerase chain reaction (RT‐PCR). In vivo, the thrombus size increased significantly when treated with IS6 compared with control‐treated mice (5388 ± 1035 μm2 vs. 2845 ± 1711 μm2). In vitro, IS6 induced significant expression of TF and E‐selectin on HUVEC, when compared with control preparation (3·1‐ and 5·1‐fold increase compared with the control‐treated cells). RT‐PCR analysis of TF mRNA transcription showed a 2·5‐fold increase of IS6‐treated cells over the value obtained with control‐treated cells. Taken together, these data show that IS6 monoclonal anti‐prothrombin antibody promotes thrombosis and this is associated with TF and E‐selectin expression.
Changes in compaction stress distributions in roots resulting from canal preparation
Authors: Versluis A. , Messer H. H. , Pintado M. R.
Published: September 2006

Aim  To examine if canal enlargement with instruments of controlled taper leads to more uniform stress distributions within a root, thereby reducing fracture susceptibility.

Methodology  Finite element models of a mandibular incisor were constructed with round and oval canal profiles, based on measurements from extracted teeth. The shapes of rotary nickel–titanium instruments (ProTaper F1, F2, and F3 and ProFile size 30, 0.04 taper and size 30, 0.06 taper; Dentsply Maillefer) were superimposed on the canals. Equivalent stresses and circumferential stresses in the root were calculated for a compaction load.

Results  The highest stresses were found at the canal wall. Round canals showed lower uniform distributions, whilst oval canals showed uneven distributions with high concentrations at the buccal and lingual canal extensions and greater stresses in the coronal and middle thirds than in the apical third. Preparation of round canals introduced only small circumferential stress increases in the apical half; preparation of oval canals produced substantial reductions where the canal was enlarged to a smooth round shape. Even where fins were not completely eliminated, the maximum stresses were still reduced by up to 15%. External distal and mesial surfaces of roots with oval canals showed moderate stress concentrations that were minimally affected by preparations, whilst stress concentrations emerged on roots with round canals when preparation sizes increased.

Conclusions  The potential for reducing fracture susceptibility exists as a result of round canal profiles achieved and smooth canal taper. Even when fins were not contacted by the instrument, stresses within the root were lower and more evenly distributed than before preparation.
Cytotoxicity of Epiphany® and Resilon® with a root model
Authors: Susini G. , About I. , Tran‐Hung L. , Camps J.
Published: September 2006

Aim  To record the cytotoxicity of Resilon and Epiphany (Pentron clinical technologies, Wallingford, CT, USA) using a root model.

Methodology  Thirty teeth with single roots were sectioned at the enamel–cementum junction, the root canals prepared and each root then sterilized before filling with the lateral condensation technique using one of three filling materials (n = 10 per group): Resilon and Epiphany, Sealite (Septodont, Pierre Rolland, Merignac, France) and gutta‐percha, Roekoseal Automix (Coltène/Whaledent, Langenau, Germany) and gutta‐percha. The roots were stored at 37 °C in an incubator to allow for setting of the root filling materials. The apices of the roots were dipped in 1 mL of MEM culture medium for 1, 2, 7 and 30 days renewing the medium every day. After 24 h contact between the medium and the filled roots, the medium was used to measure the cytotoxicity on mouse fibroblasts L 929 with the MTT assay that recorded the mitochondrial activity of the target cells. An additional test according to ISO 10993‐5 standards was undertaken to compare Resilon and Epiphany.

Results  The root model showed no statistically significant differences between the sealers at 7 and 30 days (NS). Epiphany and Resilon were the most cytotoxic materials at 1 and 2 days (P < 0.001). Unlike Epiphany, Resilon was not cytotoxic when tested according to ISO 10993‐5 standards.

Conclusions  The cytotoxicity of Resilon + Epiphany, due mainly to Epiphany, decreased after 2 days to reach a level comparable with commonly used root canal sealers.
The influence of various automated devices on the shaping ability of Mtwo rotary nickel‐titanium instruments
Authors: Bürklein S. , Schäfer E.
Published: September 2006

Aim  To compare the shaping ability of Mtwo rotary nickel‐titanium instruments in simulated curved canals and in curved canals of extracted teeth when set into permanent rotation with two different torque‐limited automated devices.

Methodology  Root canal instrumentation was performed with two different torque‐limited automated devices (Mtwo direct handpiece and Endo IT motor) using Mtwo rotary nickel‐titanium instruments up to size 35. Simulated canals: 28° and 35° curved canals in resin blocks (n = 20 canals in each group) were prepared. Pre‐ and post‐instrumentation images were recorded and assessment of canal shape was completed with a computer image analysis program. Extracted teeth: a total of 40 curved root canals were divided into two groups, which were balanced with respect to the angle and the radius of canal curvature. Straightening of the canal curvatures was determined with a computer image analysis program. Incidence of canal aberrations, preparation time, changes of working length and instrument failures were recorded both in simulated and real canals and were analysed using the t‐test and a chi‐square test.

Results  In simulated canals, instrumentation with Endo IT was significantly faster than with Mtwo direct (P < 0.05). No significant differences between the two devices were noted when all other parameters were assessed (P > 0.05). Only one instrument separated (Mtwo direct) during the enlargement of 28° curved simulated canals. All systems maintained working distance well.

Conclusions  Both systems respected original root canal curvature well and were safe, indicating that the Mtwo direct handpiece is suitable for preparing curved root canals with the Mtwo instruments.
An evaluation of localized debonding between fibre post and root canal wall by finite element simulation
Authors: Yu W. J. , Kwon T. Y. , Kyung H. M. , Kim K. H.
Published: September 2006

Aim  To investigate the effect of localized bonding defects between fibre post and root canal wall on the stress distribution in the radicular dentine.

Methodology  A tooth restored with a fibre post together with the alveolar bone were axisymmetrically modelled. A total of four models with localized debonding at the post to canal wall interface in different locations were analysed: Model A: perfect bonding layer over the entire interface; Model B: debonding at the cervical 1/3 of the interface; Model C: debonding at the mid 1/3; and Model D: debonding at the apical 1/3. A tooth restored without using a post was also included as the control (Model E). A load of 50 N was applied to the top of the full veneer cast crown at angles of 0, 15, 30, and 45° with the tooth's longitudinal axis. The stress distribution across the fibre post and root dentine was compared.

Results  Higher stresses were generated in the radicular dentine as a function of the load angle. The differences in the stress distribution were negligible between the four models and virtually the same as that for model E (control).

Conclusions  In this simulation, localized debonding at the fibre post to root canal wall interface, regardless of its location along the post, had little effect on the stress distribution in the root dentine.
ORIGINAL ARTICLE: Can Ellenberg's indicator values for Mediterranean plants be used outside their region of definition?
Authors: Godefroid Sandrine , Dana Elías D.
Published: September 2006

Aim  The aims of this study are: (1) to explore the relationships between the Ellenberg indicator values (light, temperature and moisture) recently developed for two Mediterranean regions (Italy and Greece); and (2) to evaluate the possibility of using these values in other Mediterranean areas.

Location  Southern Greece and the Mediterranean part of Italy.

Methods  A global matrix containing 966 items of information (161 species × 3 indicator variables × 2 values assigned in each study, one in Italy and one in Greece) was constructed. A test of the accuracy of the values in predicting actual environmental conditions was provided using a detrended correspondence analysis (DCA) on published vegetation relevés from the Mediterranean region. The gamma statistic was used to express relationships of ecological indicator values between the two regions, and pairs of indicator values calculated for each species were compared using Wilcoxon matched pairs tests.

Results  The results showed that indices developed for Greece and Italy were not similarly correlated to sample scores along DCA axis 1. Species’ indicator values for Italy and for Greece were highly significantly correlated for light and moisture and significantly correlated for temperature, but the correlations were weak (0.20 ≤ gamma ≤ 0.31). Pairwise testing gave significantly different indicator values for the two regions. Discrepancies below or equal to 2 units on 9‐point scales (12 points for moisture) were found for 88%, 70% and 54% of the species respectively for light, temperature and moisture indices. A substantial number of species showed higher discrepancies, from 3 up to 6 units.

Main conclusions  In the light of the present work, it seems clear that the indicator values developed for Italy and for Greece should not be used outside the region for which they were defined. This constitutes additional evidence that indicator values can be influenced by the identity of potential competitors. It also underlines the need to use standardized methods for calibrating indicator values against measured variables in such a way that indicator systems can serve as general reference systems.
Experimental induction of nocardiosis in yellowtail, Seriola quinqueradiata Temminck & Schlegel by artificial challenge
Authors: Itano T , Kawakami H , Kono T , Sakai M
Published: September 2006

Challenge methods for inducing nocardiosis, caused by Nocardia seriolae in yellowtail, Seriola quinqueradiata, were evaluated. The first method involved intraperitoneal injection of 1.1 × 102, × 103 and × 104 cfu of N. seriolae; the second was by bath immersion with three different concentrations of bacterial suspension for 10 min; the third was by intradermal injection using a multipuncture device; the fourth was by oral administration using a tube; the fifth was based on the co‐habitation of uninfected fish with others that had been artificially infected, i.e. intraperitoneally or by immersion for 10 min. The LD50 values for the infection trials were 1.9 × 102 (intraperitoneal injection), 1.5 × 104 mL−1 (immersion), 4.3 × 106 (intradermal injection) and 1.7 × 107 (oral administration). In the co‐habitation challenge, mortalities were 70% and 50% in groups of non‐infected fish mixed with fish infected by the i.p. injection and immersion methods, respectively. Fish challenged by intraperitoneal injection developed adhesions. Fish challenged by other methods did not show any gross clinical signs and moribund fish were similar to natural infection.
Effect of month of vaccine administration on antibody responses in The Gambia and Pakistan
Authors: Moore Sophie E. , Collinson Andrew C. , Fulford Anthony J.C. , Jalil Fehmida , Siegrist Claire‐Anne , Goldblatt David , Hanson Lars Å. , Prentice Andrew M.
Published: September 2006

Objective  To explore the relationship between calendar month of administration and antibody (Ab) response to vaccination in subjects from The Gambia and Pakistan, two countries with distinct patterns of seasonality.

Methods  Three cohorts were investigated: Responses to rabies and pneumococcal vaccine were assessed in 472 children (mean age 8 years, males 53%) from rural Gambia. Responses to tetanus, diphtheria and hepatitis B (HBsAg) were investigated in 138 infants also from The Gambia (birth to 52 weeks of age, males 54%). Responses to rabies and Vi typhoid vaccines were assessed in 257 adults from Lahore, Pakistan (mean age 29.4 years, males 57%).

Results  In Gambian children, significant associations were observed between month of vaccination and Ab response for the pneumococcal and rabies vaccines. As no consistent pattern by month was observed between the responses, it is assumed that different immunomodulatory stimuli or mechanisms were involved. In Pakistani adults, a significant pattern by month of vaccination was observed with both rabies and typhoid vaccine. No monthly influences were observed in the infant study to the tetanus, diphtheria or the HbsAg vaccines.

Conclusions  Antibody responses to certain specific vaccines are influenced by month of administration. Further research is required to elucidate the precise mechanisms explaining these observations, but a co‐stimulatory effect of seasonally variable environmental antigens is a likely cause. Future studies of Ab response to vaccination in countries with a seasonally dependent environment should consider month of vaccination when interpreting study findings.
Risk factors for injuries in young children in four developing countries: the Young Lives Study
Authors: Howe L. D. , Huttly S. R. A. , Abramsky T.
Published: September 2006

Objective  To assess the occurrence of child injury in four developing country settings and to explore potential risk factors for injury.

Methods  Injury occurrence was studied in cohorts of 2000 children of age 6–17 months at enrolment, in each of Ethiopia, Peru, Vietnam and India (Andhra Pradesh). Generalized estimating equation models were used to explore potential risk factors for child injury.

Results  Occurrence of child injury was high in all countries. Caregiver depression emerged as a consistent risk factor for all types of injury measured (burns, serious falls, broken bones and near‐fatal injury) across all countries. Other risk factors also showed consistent associations, including long‐term child health problems, region of residence and the regular care of the child by a non‐household member.

Conclusions  This report provides further evidence of the importance of childhood injury in developing countries and emphasizes the importance of including infants in injury research and prevention strategies. It provides strong evidence of an association between caregiver mental health and child injury risk and contributes to the limited knowledge base on risk factors for child injury in developing countries.
Finding patients eligible for antiretroviral therapy using TB services as entry point for HIV treatment
Authors: Bwire Robert , Nagelkerke Nico J. D. , Borgdorff Martien W.
Published: September 2006

Objective  To estimate the proportion of antiretroviral therapy (ART) eligible adults (15–49 years) with tuberculosis potentially identifiable through tuberculosis services using a CD4 count below 350 cells/mm3 as cut‐off value for ART initiation.

Methods  Using TB notification rate data, HIV seroprevalence data, and estimates of the size of the adult population (15–49 years) in 18 sub‐Saharan African countries with an HIV seroprevalence of > 5%, calculations of the number of ART eligible adults with tuberculosis presenting to tuberculosis services were made. Assumptions were made on the tuberculosis notification rates in the age‐group 15–49 years, the HIV‐infected population with a CD4 count below 350 cells/mm3 and the relative risk of developing tuberculosis, and average duration from HIV infection to death. The probability of having a CD4+ count below 350 cells/mm3 given a diagnosis of tuberculosis was estimated using Bayes’ theorem, and estimates of the number of patients with a CD4 count below 350 cells/mm3 identifiable through tuberculosis were made. The number needed to screen to identify one ART eligible patient through tuberculosis services was estimated for each country.

Results  ART eligible adults with tuberculosis potentially identifiable through tuberculosis services in the 18 countries ranged from 2% to 18% of the total HIV‐infected adult population with a CD4+ count below 350 cells/mm3 and would average 10% of all such HIV patients. The number needed to screen to identify ART eligible patients through tuberculosis services ranged from 1.4 to 4.2, against 8.6 to 65.4 if adults aged 15–49 are randomly screened for low CD4 counts.

Conclusion  Tuberculosis services are an important entry point for identifying ART eligible patients. Given that dually infected patients identified through tuberculosis services contributed to 10% of the HIV‐infected adult population with a CD4 cell count below 350 cells/mm3 in the 18 sub‐Saharan African countries, major efforts are required beyond the tuberculosis services in detecting patients that should benefit from ART. However, the low number needed to screen gives opportunity to use tuberculosis services in AIDS control and ART scaling‐up programmes.

keywords  HIV
,
tuberculosis
,
CD4+ count , ART , Bayes’ theorem , screening
Dose‐dependent schistosome‐induced mortality and morbidity risk elevates host reproductive effort
Authors: BLAIR L. , WEBSTER J. P.
Published: September 2006

Parasitism changes the host environment and may influence resource allocation between reproductive effort and somatic maintenance. We characterized the impact of dose‐dependent schistosome exposure and/or infection establishment on intermediate host survival and reproduction. Four matched groups of Biomphalaria glabrata snails were individually exposed to increasing doses of Schistosoma mansoni parasites, with a fifth control group remaining unexposed. Increased mortality was observed amongst both snails infected and also those snails exposed to the parasite but within which infection did not establish, although only exposed but uninfected snails showed a dose‐dependent increase in mortality. Snails also facultatively altered their reproductive output in response to parasite exposure: egg mass production decreased with increasing parasite dose in patently infected snails, whilst, in contrast, exposed but uninfected snails demonstrated a positive association between egg mass production and parasite dose in the post‐patent period. These results uniquely suggest an exposure‐dose‐dependent post‐patent fecundity compensation occurring in relation to the risk of future parasite‐associated mortality.
Worker Turnover, Capital Dispersion, and Matching
Authors: Dale‐Olsen Harald
Published: September 2006

Abstract.  A model acknowledging technology and wage dispersion, search frictions, and costly worker turnover is used for testing the notion of random matching. Using a linked employer–employee data set on roughly 9,000 Norwegian establishments and 200,000 jobs during the period 1989–95, I show that establishments investing more in capital, pay more, and experience lower worker turnover rate. Strictly convex turnover costs are identified. High‐wage establishments post on average less intensively than low‐wage establishments. Positive relationships between wages and posting are observed for high‐tech industries and in the capital and surroundings. Thus, the notion of random matching is generally rejected.
Financing Unemployment Benefits: Dismissal versus Employment Taxes
Authors: Baumann Florian , Stähler Nikolai
Published: September 2006

Abstract.  This paper investigates the effects of using dismissal taxes to finance unemployment benefits. We compare dismissal and employment taxes in a model with search frictions. Employment taxes give rise to externalities because firms do not take into account the effects their dismissal decisions have on others. These externalities can be tackled by using dismissal taxes to finance unemployment insurance. Taking into account the budget for unemployment insurance, employment taxes can be reduced by more than is necessary to offset the adverse effect of dismissal taxes on the value of the firm. The introduction of dismissal taxes leads to higher job creation and lower unemployment.
Explaining the Growth of Part‐time Employment: Factors of Supply and Demand
Authors: Euwals Rob , Hogerbrugge Maurice
Published: September 2006

Abstract.  Using the Dutch Labour Force Survey 1991–2001, the authors investigate the incidence of part‐time employment in the country with the highest part‐time employment rate of the OECD countries. Women fulfil most part‐time jobs, but a considerable fraction of men works part‐time as well. Evidence from descriptive statistics and a macroeconometric model at the sectoral level of industry suggests that the growth of part‐time employment in the 1990s relates strongly to the growth in female labour force participation. Factors of labour demand, such as the shift from manufacturing to services and the increase in the demand for flexible labour, turn out to play a significant role as well.
The Quality of Industrial Relations and Labour Market Performance
Authors: Feldmann Horst
Published: September 2006

Abstract.  Using data from 19 industrial countries for the period 1985–2002, this paper analyses whether the quality of industrial relations affects unemployment and employment rates. To measure the quality of industrial relations, we use the results of surveys in which senior business executives characterized the industrial relations of their countries. Controlling for the impact of major labour market institutions, the business cycle, the level of economic development, unobserved country effects, as well as endogeneity, we find that cooperative industrial relations are likely to lower unemployment and to increase employment. The effects appear to be large, particularly among young people.
MORPHOLOGY, MOLECULAR PHYLOGENY AND TAXONOMY OF TWO NEW SPECIES OF PLEODORINA (VOLVOCEAE, CHLOROPHYCEAE)1
Authors: Nozaki Hisayoshi , Ott Franklyn D. , Coleman Annette W.
Published: September 2006

The volvocacean genus Pleodorina has been morphologically characterized as having small somatic cells in spheroidal colonies and anisogamous sexual reproduction with sperm packets. In this study we examined two new species that can be assigned to the genus Pleodorina based on morphology: P. starrii H. Nozaki et al. sp. nov. and P. thompsonii F. D. Ott et al. sp. nov. P. starrii was collected from Japan and had 32‐ or 64‐celled colonies with anterior somatic cells and spheroidal individual cellular sheaths that were weakly attached to each other within the colonial envelope. P. thompsonii from Texas (USA) exhibited four or 12 somatic cells in the anterior pole of 16‐ or 32‐celled colonies, respectively, and had a single large pyrenoid in the chloroplast of mature reproductive cells. The chloroplast multigene phylogeny placed P. starrii and P. indica (Iyenger) H. Nozaki in a clade that was robustly separated from the type species P. californica Shaw and P. japonica H. Nozaki. Pleodorina thompsonii was resolved as a basal branch within a large monophyletic group (Eudorina group) composed of Eudorina, Pleodorina and Volvox (excluding section Volvox). Thus, Pleodorina was found among three separate lineages within the Eudorina group in which Eudorina and Volvox were also resolved as nonmonophyletic. The DNA sequences from additional species/strains as well as recognition of morphological attributes that characterize the monophyletic groups within the Eudorina group are needed to construct a natural generic classification within these members of the Volvocaceae.