bluuebunny/crossref_metadata_2025 huggingface dataset:
Acute mortality during long‐distance ski races (Vasaloppet)
Authors: Farahmand B. , Hållmarker U. , Brobert G. P. , Ahlbom A.
Published: August 2006

Objective:We studied mortality during long‐distance ski races in Sweden.

Design:The cohort comprised all subjects who participated in ski races during the Vasaloppet week from 1970 through 2005. All deaths during the races were identified and compared with the corresponding expected numbers based on national death rates.

Results:In total, 698 102 starters generated altogether 581 person‐years of skiing. Overall, 13 deaths occurred compared with 1.68 expected during the skiing time, yielding a standardized mortality ratio (SMR) of 7.7 [95% confidence interval (CI) 4.1–13.2]. Twelve of the deaths were caused by cardiovascular disease (SMR=22.1, 95% CI 11.4–38.6). Interviews of relatives revealed that two to four victims had medical conditions of the sort that they probably would have been recommended to avoid participation for medical reasons had they consulted a physician.

Conclusion:Our study showed a clearly increased risk of acute mortality during long‐distance skiing. However, as physically active people spend only a minority of their time in races, in that population the short‐term excess mortality during these periods is by far outweighed by the long‐term protective effects of exercise on mortality.
Distinct Clathrin‐Coated Pits Sort Different G Protein‐Coupled Receptor Cargo
Authors: Mundell Stuart J. , Luo Jiansong , Benovic Jeffrey L. , Conley Pamela B. , Poole Alastair W.
Published: August 2006

Upon activation, many G protein‐coupled receptors (GPCRs) internalize by clathrin‐mediated endocytosis and are subsequently sorted to undergo recycling or lysosomal degradation. Here we observe that sorting can take place much earlier than previously thought, by entry of different GPCRs into distinct populations of clathrin‐coated pit (CCP). These distinct populations were revealed by analysis of two purinergic GPCRs, P2Y1and P2Y12, which enter two populations of CCPs in a mutually exclusive manner. The mechanisms underlying early GPCR sorting involve differential kinase‐dependent processes because internalization of P2Y12is mediated by GPCR kinases (GRKs) and arrestin, whereas P2Y1internalization is GRK‐ and arrestin‐independent but requires protein kinase C. Importantly, the β2adrenoceptor which also internalizes in a GRK‐dependent manner also traffics exclusively to P2Y12‐containing CCPs. Our data therefore reveal distinct populations of CCPs that sort GPCR cargo at the plasma membrane using different kinase‐dependent mechanisms.
Vaccinia‐Virus‐Induced Cellular Contractility Facilitates the Subcellular Localization of the Viral Replication Sites
Authors: Schramm Birgit , de Haan Cornelis A.M. , Young Joanne , Doglio Laura , Schleich Sibylle , Reese Christoph , Popov Andrei V. , Steffen Walter , Schroer Trina , Locker Jacomine Krijnse
Published: August 2006

Poxviruses, such as vaccinia virus (VV), replicate their DNA in endoplasmic‐reticulum‐enclosed cytoplasmic sites. Here, we compare the dynamics of the VV replication sites with those of the attenuated strain, modified VV Ankara (MVA). By live‐cell imaging, small, early replication sites of both viruses undergo motility typical of microtubule (MT)‐motor‐mediated movement. Over time, growing replication sites of VV collect around the nucleus in a MT‐dependent fashion, whereas those of MVA remain mostly scattered in the cytoplasm. Surprisingly, blocking the dynein function does not impair the perinuclear accumulation of large VV replication sites. Live‐cell imaging demonstrates that in contrast to small replication sites, large sites do not display MT‐motor‐mediated motility. Instead, VV infection induces cellular contractility that facilitates the collection of growing replication sites around the nucleus. In a subset of cells (30–40%), this VV‐induced contractility is alternated by phases of directed cell migration, suggesting that the two processes may be linked. The MVA‐infected cells do not display contractility or cell migration, supporting the idea that these cellular activities facilitate the efficient accumulation of the VV replication sites around the nucleus. We propose that the recently described cytoskeletal rearrangements induced by VV are a prerequisite for the observed cell contractility and migration activities that apparently contribute to the organization of the complex cytoplasmic life cycle of VV.
Multilayer Interactions Determine the Golgi Localization of GRIP Golgins
Authors: Lu Lei , Tai Guihua , Wu Mousheng , Song Haiwei , Hong Wanjin
Published: August 2006

Golgin‐97, RanBP2α, Imh1p and p230/golgin‐245 (GRIP) domain golgins are targeted to the Golgi membrane through their GRIP domains. By analyzing more than 30 mutants of golgin‐97 and golgin‐245 GRIP domains for their properties of dimerization, interaction with ARF like protein 1 (Arl1)‐GTP and Golgi targeting, we found hierarchically organized three‐tier interactions governing the Golgi targeting of GRIP domain golgins. GRIP domain self‐dimerization is necessary for bivalent interaction with Arl1‐GTP. Unexpectedly, however, these two interactions are not sufficient for Golgi targeting, as a third group of residues, including positive‐charged arginine between α1 and α2 and hydrophobic residues C‐terminal to the GRIP domain, turn out to be essential. Surface plasmon resonance analysis indicates that GRIP domain interacts directly with membrane lipid, partially through the third group of residues such as W744 of golgin‐97. This third tier of interaction with the membrane could be mediated by non‐specific hydrophobic and electrostatic forces.
Knowledge of Jordanian mothers with regards to emergency management of dental trauma
Authors: Al‐Jundi Suhad H.
Published: August 2006

Abstract –  Studies in Jordan indicated that delay in seeking emergency management of dental trauma leads to unfavorable outcome of even mild forms of trauma. The purpose of this cross‐sectional study was to assess, by means of a structured questionnaire, the level of general knowledge of mothers in Jordan with regards to the immediate emergency management of dental trauma, and its relation to socioeconomic variables. The questionnaire surveyed mothers’ demographic data, basic knowledge of immediate management of tooth fracture, avulsion, and loss of consciousness. It also investigated the participants self assessed knowledge, attitude to public education, and knowledge of availability and priority of emergency services for trauma in Jordan. The sample consisted of 2215 mothers who attended mother and child care centers in the capital Amman, and in Irbid (the second largest city in Jordan) over a period of 3 months (July to September, 2003). Overall the participants’ basic knowledge with regards to the emergency management of the trauma cases presented in the questionnaire was deficient regardless of age, level of education, socioeconomic class, or number of previous encounters with dental trauma. Generally, the attitude to public education on the topic was positive and chi‐square test indicated that the level of education of mothers positively affected their knowledge of ‘during working hour’ emergency services and the importance of immediate management of dental trauma. Educational programs that can be added to the mother and child care advice protocols may help improve the knowledge and awareness of mothers and therefore improve the outcomes of dental trauma.
Knowledge of oral health professionals of treatment of avulsed teeth
Authors: Cohenca Nestor , Forrest Jane L. , Rotstein Ilan
Published: August 2006

Abstract –  The management and immediate treatment of an avulsed permanent tooth will determine the long‐term survival of the tooth. The aim of this study was to evaluate the knowledge of oral health professionals on the new guidelines for emergency treatment of avulsed teeth. A 12‐item questionnaire was distributed among general dentists, specialists, dental hygienists and dental assistants attending Continuing Education courses at the School of Dentistry, University of Southern California, between 2003 and 2004. This study reports only on the general practitioners who comprised 83% of the participants. The results revealed an uneven pattern of knowledge among them regarding the emergency management of an avulsed tooth. Statistically significant associations were related to the participants’ previous dental trauma education and their age. In conclusion, there is a need to improve the knowledge of general dentists in the current guidelines for emergency treatment of avulsed teeth.
Radiographic Analysis of the Transcrestal Sinus Floor Elevation: Short‐Term Observations
Authors: Diserens Valérie , Mericske Ernoe , Mericske‐Stern Regina
Published: August 2006

Background:

There are some limitations for implant placement in the posterior maxilla when there is an extended sinus. Various techniques for sinus floor elevation allow an increase in implant length.

Purpose:

The aim of the present radiographic study was to assess the augmented site in the sinus around implants that were installed by means of an osteotome‐mediated transcrestal sinus floor elevation.

Materials and Methods:

Thirty‐three patients with 44 implants were available. In 39% of the implants the sinus floor elevation was performed exclusively with bone chips. Bone fill material (Bio‐Oss®, Geistlich Söhne AG, Wolhusen, Switzerland) was additionally used to increase the volume and stability of the lifted area at 61% of the implants. The visibility and morphology of the augmentation were assessed and compared by means of intraoral radiography (longcone technique).

Results:

All implants were stable and were considered to be successful when they were reexamined in the context of the present study. The mean residual bone height was 5.78 ±1.4 mm. The increase of the implant length as compared to the original bone height resulted in a mean value of 3.87 ± 2.0 mm. The volume and density of the lifted area were more visible if Bio‐Oss was added. A shrinkage and/or condensation of the grafted material was visible at 37% of the implants after a minimum loaded period of 200 days. Equally, a decreased visibility of the original sinus floor was noted at 61% of implants. The formation of a cortical bone layer at the apex of the implants was detected at 35% of implants.

Conclusions:

The surgical procedure appears to be a safe method with rare complications. Radiographic assessment of the augmentation procedure proved to be difficult, and measurements are not fully reliable.
Minimally Invasive Flapless Implant Surgery: A Prospective Multicenter Study
Authors: Becker William , Goldstein Moshe , Becker Burton E. , Sennerby Lars
Published: August 2006

Background:

Placement of implants with a minimally invasive flapless approach has the potential to minimize crestal bone loss, soft tissue inflammation, and probing depth adjacent to implants and to minimize surgical time.

Purpose:

The aim of this multicenter study was to evaluate implant placement using a minimally invasive one‐stage flapless technique up to 2 years.

Materials and Methods:

Fifty‐seven patients ranging in age from 24 to 86 years were recruited from three clinical centers (Tucson, AZ, USA; Tel Aviv, Israel; Göteborg, Sweden). Seventy‐nine implants were placed. A small, sharp‐tipped guiding drill was used to create a precise, minimally invasive initial penetration through the mucosa and into bone (Nobel Biocare, Yorba, Linda, CA, USA). Implants were placed according to the manufacturer's instructions, with minimal countersinking. The parameters evaluated were total surgical time, implant survival, bone quality and quantity, implant position by tooth type, depth from mucosal margin to bone crest, implant length, probing depth, inflammation, and crestal bone changes. At 2 years, for 79 implants placed in 57 patients, the cumulative success rate using a minimally invasive flapless method was 98.7%, indicating the loss of 1 implant. Changes in crestal bone for 77 baseline and follow‐up measurements were insignificant (radiograph 1: mean 0.7 mm, SD 0.5 mm, range 2.8 mm, minimum 0.2 mm, maximum 3.0 mm; radiograph 2: mean 0.8 mm, SD 0.5 mm, range 3.4 mm, minimum 0.12 mm, maximum 3.5 mm). Using descriptive statistics for 78 patients (one implant lost), mean changes for probing depth and inflammation were clinically insignificant. The average time for implant placement was 28 minutes (minimum 10 minutes, maximum 60 minutes, SD 13.1 minutes). Average depth from mucosal margin to bone was 3.3 mm (SD 0.7 mm, minimum 2 mm, maximum 5 mm, range 3 mm). Thirty‐two implants were placed in maxillae and 47 in mandibles.

Conclusions:

The results of this study demonstrate that following diagnostic treatment planning criteria, flapless surgery using a minimally invasive technique is a predictable procedure. The benefits of this procedure are lessened surgical time; minimal changes in crestal bone levels, probing depth, and inflammation; perceived minimized bleeding; and lessened postoperative discomfort.
Early Loading of Interforaminal Implants Immediately Installed after Extraction of Teeth Presenting Endodontic and Periodontal Lesions
Authors: Villa Roberto , Rangert Bo
Published: August 2006

Background:

Infection in tooth extraction sites has traditionally been considered an indication to postpone implant insertion until the infection has been resolved.

Purpose:

The aim of this study was to evaluate the survival rate of early‐loaded implants placed immediately after extraction of teeth with endodontic and periodontal lesions in the mandible.

Materials and Methods:

Twenty patients in need of mandibular implant treatment and with teeth showing signs of infection in the interforaminal area were included in the study. The patients received four to six implants (Brånemark System®, Nobel Biocare AB, Göteborg, Sweden) in or close to the fresh extraction sockets and received a provisional prosthesis within 3 days. Final prostheses were delivered after 3 to 12 months. The surgical protocol paid special attention to the preservation of high implant stability and control of the inflammatory response. The patients were followed up for 15 to 44 months.

Results:

No implants were lost, resulting in a 100% survival rate. A mean marginal bone loss of 0.7 mm (SD 1.2 mm) was registered during the observation period. No signs of infection around the implants were detected at any follow‐up visit.

Conclusion: A high survival rate can be achieved for immediately placed and early‐loaded implants in the mandible despite the presence of infection at the extracted teeth.
Immediate Occlusal Loading of Brånemark System® TiUnite™ Implants Placed Predominantly in Soft Bone: 4‐Year Results of a Prospective Clinical Study
Authors: Schärer Peter , Glauser Roland , Ruhstaller Petra , Windisch Simone , Zembic Anja , Lundgren AnnaKarin , Gottlow Jan , Hämmerle Christoph H. F.
Published: August 2006

Background:

Immediate occlusal implant loading has been documented as a viable treatment option for various indications. However, most of the available studies reported on the short‐term outcome of this treatment modality.

Purpose:

The purpose of this prospective clinical study was to document, on a long‐term basis, the outcome of immediate occlusally loaded Brånemark System® Mk IV TiUnite™ (Nobel Biocare AB, Göteborg, Sweden) implants placed to support fixed reconstructions in various regions of the jaws.

Materials and Methods:

Thirty‐eight patients received a total of 51 fixed prosthetic reconstructions, all of which were connected on the day of implant insertion. Twenty restorations replaced single teeth, 30 were fixed partial dentures, and 1 was a full‐arch fixed lower restoration. These prostheses were supported by 102 Brånemark System Mk IV TiUnite implants (38 maxillary and 64 mandibular), the majority of which were placed in posterior regions (88%) and mainly in soft bone (76%). Resonance frequency measurements and marginal periimplant soft tissue evaluations were conducted during the course of the study. Furthermore, radiographic examinations were performed at the time of prosthesis delivery and at the 1‐ and 6‐month and 1‐, 2‐, 3‐, and 4‐year follow‐up visits. This report summarizes the results after 4 years of loading.

Results:

Three maxillary implants were removed, although stable, in one patient at the 8‐week follow‐up owing to postoperative infection in the adjacent guided bone regeneration area. No implants were lost further on. This resulted in a cumulative implant success rate of 97.1% after 4 years of prosthetic loading. The mean marginal bone remodeling after 4 years of function was 1.3 ± SD 0.9 mm. At 4 years, absence of marginal plaque and bleeding on probing was reported for 87% and 69% of the sites, respectively, thereby remaining unchanged since the 1‐year follow‐up. On average, the inter‐proximal soft tissue fill increased for both mesial and distal papillae from scores of 1.4 ± 1.1 and 1.0 ± 1.1, respectively, at the preoperative assessment to 2.0 ± 0.8 and 1.7 ± 0.8, respectively, at the 4‐year assessment.

Conclusion:

The applied immediate loading protocol, in combination with a slightly tapered implant design and a modified implant surface texture, was shown to be a successful treatment alternative in regions exhibiting soft bone.
One‐Year Results of a Prospective Multicenter Study on Brånemark System® Implants with a TiUnite™ Surface
Authors: Friberg Bertil , Dahlin Christer , Widmark Göran , Östman Pär‐Olov , Billström Camilla
Published: August 2006

Background:

A moderately rough surface implant (TiUnite™, Nobel Biocare AB, Göteborg, Sweden) was introduced in 2000. Laboratory studies and some clinical studies have demonstrated excellent bone response in the early healing phase.

Purpose:

The aim of this prospective multicenter study was to follow a large number of consecutively treated patients using Brånemark System® implants with the TiUnite surface. The current report constitutes the 1‐year data of a planned 3‐year study.

Materials and Methods:

Originally, the study comprised 43 surgeons from 22 centers in Sweden, Norway, and Finland. Five centers were excluded from the study because of poor compliance. Thus, 187 patients treated with 478 TiUnite implants were followed during 1 year of function. The majority of implants were inserted in maxillae (357 implants), and 78 of the implant sites were assigned the quality 4 figure. Radiographic evaluations were performed.

Results:

Five implants were lost up to and including the 1‐year follow‐up, revealing implant cumulative survival rates of 98.6% and 100% for maxillae and mandibles, respectively. Three implants failed in quality 4 bone (3.8%). The mean marginal bone resorption at the end of the study period was 1.4 mm. The number of withdrawals of patients during the first year was high (19.3%).

Conclusion:

The present investigation showed a high implant cumulative survival rate of 98.9%. Values of marginal bone resorption were within normal ranges. No adverse effects of the TiUnite surface were reported, and complications during the study period were few and similar to those reported for the turned implant surface. However, the high number of excluded patients and the relatively high number of withdrawals must be observed and considered when interpreting data.
Oxidized Titanium Implants in Reconstructive Jaw Surgery
Authors: Brechter Magnus , Nilson Hans , Lundgren Stefan
Published: August 2006

Background:

Rehabilitation with implant‐supported bridges in patients with insufficient bone volumes may require bone reconstructive procedures in conjunction with or prior to implant placement. Clinical follow‐up studies using turned titanium and bone grafts have demonstrated higher failure rates than when used in nongrafted patients. Improved bone integration has been demonstrated for oxidized titanium implants; however, their clinical performance in bone reconstruction situations is not known.

Purpose:

This study was performed to analyze the survival and stability of oxidized titanium implants placed in patients subjected to reconstructive jaw surgery at one clinic.

Materials and Methods:

Two hundred oxidized titanium implants (Mk III, TiUnite™, Nobel Biocare AB, Göteborg, Sweden) were placed in 47 patients in conjunction with or secondary to six different reconstructive procedures owing to insufficient bone volume. In all six groups, implant stability was assessed by resonance frequency analysis and manually checked for rotation stability at implant insertion, at the time of abutment connection, and after a minimum of 12 months of loading of the prosthetic construction. Periapical radiographs were taken after a minimum of 12 months of loading (mean 21 months) for evaluation of the marginal bone levels. The mean clinical follow‐up period was 30 months.

Results:

Of the 200 implants, 199 were considered osseointegrated at the time of abutment surgery. At the 12‐month post‐loading follow‐up, another two implants were considered not stable. Three implants (1.5%) were ranked as unsuccessful.

Conclusion:

Clinical experience with 200 consecutive oxidized implants in various reconstruction situations shows a successful outcome, with only three failures (1.5%) during a mean follow‐up period of 30 months.
All‐on‐4 Immediate‐Function Concept with Brånemark System® Implants for Completely Edentulous Maxillae: A 1‐Year Retrospective Clinical Study
Authors: Maló Paulo , Rangert Bo , Nobre Miguel
Published: August 2006

Background:

Immediate implant function has become an accepted treatment modality for fixed restorations in totally edentulous mandibles, whereas experience from immediate function in the edentulous maxilla is limited.

Purpose:

The purpose of this study was to evaluate a protocol for immediate function (within 3 hours) of four implants (All‐on‐4, Nobel Biocare AB, Göteborg, Sweden) supporting a fixed prosthesis in the completely edentulous maxilla.

Materials and Methods:

This retrospective clinical study included 32 patients with 128 immediately loaded implants (Brånemark System® TiUnite™, Nobel Biocare AB) supporting fixed complete‐arch maxillary all‐acrylic prostheses. A specially designed surgical guide was used to facilitate implant positioning and tilting of the posterior implants to achieve good bone anchorage and large interimplant distance for good prosthetic support. Follow‐up examinations were performed at 6 and 12 months. Radiographic assessment of the marginal bone level was performed after 1 year in function.

Results:

Three immediately loaded implants were lost in three patients, giving a 1‐year cumulative survival rate of 97.6%. The marginal bone level was, on average, 0.9 mm (SD 1.0 mm) from the implant/abutment junction after 1 year.

Conclusion:

The high cumulative implant survival rate indicates that the immediate function concept for completely edentulous maxillae may be a viable concept.
Short Implants in the Severely Resorbed Maxilla: A 2‐Year Retrospective Clinical Study
Authors: Renouard Franck , Nisand David
Published: August 2006

Background:

Although the predictability of endosseous dental implants is well documented, the restoration of the posterior region of the maxilla remains a challenge. The placement of short implants is one therapeutic option that reduces the need for augmentation therapy.

Purpose:

The purpose of this retrospective study was to assess the survival rates of 6 to 8.5 mm‐long implants in the severely resorbed maxilla following a surgical protocol for optimized initial implant stability.

Materials and Methods:

The study included 85 patients with 96 short (6–8.5 mm) implants (Brånemark System®, Nobel Biocare AB, Göteborg, Sweden) supporting single‐tooth and partial reconstructions. The implants had a machined (54) or an oxidized (TiUnite™, Nobel Biocare AB) (42) surface. A one‐stage surgical protocol with delayed loading was used. The patients were followed for at least 2 years after loading (average follow‐up period 37.6 months). The marginal bone resorption was assessed by radiographic readings.

Results:

Five implants were lost during the first 9 months, and four implants were lost to follow‐up. The cumulative survival rate was 94.6%. Four of the failed implants had a machined surface, and one had an oxidized surface. The mean marginal bone resorption after 2 years in function was 0.44 ± 0.52 mm.

Conclusion:

This study demonstrates that the use of short implants maybe considered for prosthetic rehabilitation of the severely resorbed maxilla as an alternative to more complicated surgical techniques.
A Computed Tomographic Scan–Derived Customized Surgical Template and Fixed Prosthesis for Flapless Surgery and Immediate Loading of Implants in Fully Edentulous Maxillae: A Prospective Multicenter Study
Authors: van Steenberghe Daniel , Glauser Roland , Blombäck Ulf , Andersson Matts , Schutyser Filip , Pettersson Andreas , Wendelhag Inger
Published: August 2006

Background:

Based on three‐dimensional implant planning software for computed tomographic (CT) scan data, customized surgical templates and final dental prostheses could be designed to ensure high precision transfer of the implant treatment planning to the operative field and an immediate rigid splinting of the installed implants, respectively.

Purpose:

The aim of the present study was to (1) evaluate a concept including a treatment planning procedure based on CT scan images and a prefabricated fixed prosthetic reconstruction for immediate function in upper jaws using a flapless surgical technique and (2) validate the universality of this concept in a prospective multicenter clinical study.

Materials and Methods:

Twenty‐seven consecutive patients with edentulous maxillae were included. Treatments were performed according to the Teeth‐in‐an‐Hour™ concept (Nobel Biocare AB, Göteborg, Sweden), which includes a CT scan‐derived customized surgical template for flapless surgery and a prefabricated prosthetic suprastructure.

Results:

All patients received their final prosthetic restoration immediately after implant placement, that is, both the surgery and the prosthesis insertion were completed within approximately 1 hour. In the 24 patients followed for 1 year, all prostheses and individual implants were recorded as stable.

Conclusion:

The present prospective multicenter study indicates that the prefabrication, on the basis of models derived from three‐dimensional oral implant planning software, of both surgical templates for flapless surgery and dental pros‐theses for immediate loading is a very reliable treatment option. It is evident that the same approach could be used for staged surgery and in partial edentulism.
Suppression of microtubule dynamics by benomyl decreases tension across kinetochore pairs and induces apoptosis in cancer cells
Authors: Rathinasamy K. , Panda D.
Published: August 2006

We found that benomyl, a benzimidazole fungicide, strongly suppressed the reassembly of cold‐depolymerized spindle microtubules in HeLa cells. Benomyl perturbed microtubule‐kinetochore attachment and chromosome alignment at the metaphase plate. Benomyl also significantly decreased the distance between the sister kinetochore pairs in metaphase cells and increased the level of the checkpoint protein BubR1 at the kinetochore region, indicating that benomyl caused loss of tension across the kinetochores. In addition, benomyl decreased the intercentrosomal distance in mitotic HeLa cells and blocked the cells at mitosis. Further, we analyzed the effects of benomyl on the signal transduction pathways in relation to mitotic block, bcl2 phosphorylation and induction of apoptosis. The results suggest that benomyl causes loss of tension across the kinetochores, blocks the cell cycle progression at mitosis and subsequently, induces apoptosis through the bcl2–bax pathway in a manner qualitatively similar to the powerful microtubule targeted anticancer drugs like the vinca alkaloids and paclitaxel. Considering the very high toxicity of the potent anticancer drugs and the low toxicity of benomyl in humans, we suggest that benomyl could be useful as an adjuvant in combination with the powerful anticancer drugs in cancer therapy.
Planetesimal formation via fragmentation in sel-gravitating protoplanetary discs
Authors: Rice W. K. M. , Lodato G. , Pringle J. E. , Armitage P. J. , Bonnell I. A.
Published: August 2006

An unsolved issue in the standard core accretion model for gaseous planet formation is how kilometre-sized planetesimals form from, initially, micron-sized dust grains. Solid growth beyond metre sizes can be difficult both because the sticking efficiency becomes very small, and because these particles should rapidly migrate into the central star. We consider here how metre-sized particles evolve in sel-gravitating accretion discs using simulations in which the gravitational influence of the solid particles is also included. Metre-sized particles become strongly concentrated in the spiral structures present in the disc and, if the solid to gas density ratio is sufficiently high, can fragment because of their own sel-gravity to form planetesimals directly. This result suggests that planetesimal formation may occur very early in the star formation process while discs are still massive enough to be sel-gravitating. The dependence of this process on the surface density of the solids is also consistent with the observation that extrasolar planets are preferentially found around high-metallicity stars.
Predictions for a planet just inside Fomalhaut's eccentric ring
Authors: Quillen Alice C.
Published: August 2006

We propose that the eccentricity and sharpness of the edge of Fomalhaut's disc are due to a planet just interior to the ring edge. The collision time-scale consistent with the disc opacity is long enough that spiral density waves cannot be driven near the planet. The ring edge is likely to be located at the boundary of a chaotic zone in the corotation region of the planet. We find that this zone can open a gap in a particle disc as long as the collision time-scale exceeds the removal or ejection time-scale in the zone. We use the slope measured from the ring edge surface brightness profile to place an upper limit on the planet mass. The removal time-scale in the chaotic zone is used to estimate a lower limit. The ring edge has eccentricity caused by secular perturbations from the planet. These arguments imply that the planet has a mass between that of Neptune and that of Saturn, a semi-major axis of approximately 119 au and longitude of periastron and eccentricity, 0.1, the same as that of the ring edge.
Three intervening galaxy absorbers towards GRB 060418: faint and dusty?
Authors: Ellison Sara L. , Vreeswijk Paul , Ledoux Cédric , Willis Jon P. , Jaunsen Andreas , Wijers Ralph A. M. J. , Smette Alain , Fynbo Johan P. U. , Møller Palle , Hjorth Jens , Kaufer Andreas
Published: August 2006

We present an analysis of three strong, intervening Mg II absorption systems (zabs = 0.603, 0.656, 1.107) towards the optical afterglow of gamma-ray burst (GRB) 060418. From high-resolution Ultraviolet and Visual Echelle Spectrograph (UVES) spectra we measure metal column densities and find that the highest redshift absorber exhibits a large amount of dust depletion compared with damped Lyman absorbers (DLAs) seen in quasi-stellar object (QSO) spectra. The intervening zabs = 1.107 absorber is also unusual in exhibiting a clear 2175-Å bump, the first time this feature has been definitively detected in a GRB spectrum. The GRB afterglow spectrum is best fitted with a two-component extinction curve: a Small Magellanic Cloud (SMC) extinction law at z = 1.49 (the redshift of the host) with E(B−V) = 0.07 ± 0.01 and a Galactic extinction curve at z∼ 1.1 with E(B−V) = 0.08 ± 0.01. We also present a moderately deep New Technology Telescope (NTT) R-band image of the GRB 060418 field and spectroscopy of four galaxies within 1 arcmin. None of these objects has a redshift that matches any of the intervening absorbers, and we conclude that the galaxies responsible for the two intervening Mg ii absorbers at z∼ 0.6 have luminosities .
Research use in the care of older people: a survey among healthcare staff
Authors: Boström Anne‐Marie , Wallin Lars , Nordström Gun
Published: August 2006

Background.  Sweden has one of the largest proportions of older people in the world. To manage the healthcare needs of an aging population, there has been an alteration from hospital care to community‐based care. In these settings, the majority of staff is enrolled nurses (EN) and nurse aides (NA) without university education.

Aim and design.  The overall aim of this cross‐sectional survey was to explore staff perceptions of factors related to research utilization in the care of older people.

Method.  Questionnaires covering research utilization and demographics were sent to all staff (n = 132) working in seven units in older people care. The response rate was 67% (n = 89). The respondents consisted of ENs/NAs (n = 63), Registered Nurses (RN) and rehabilitation professionals (RP) as physiotherapists and occupational therapists (RN/RP n = 26).

Results.  Most of staff reported positive attitudes towards research. The RNs/RPs stated more often than the ENs/NAs that they wanted to base their practice on research (81% vs. 25%; P = 0.001). The RNs/RPs also reported a greater extent of research use in daily practice (54% vs. 17%; P = 0.001). Support from colleagues (77% vs. 22%; P < 0.001) and unit managers (73% vs. 10%; P < 0.001) for implementing research findings was also more frequently reported by the RNs/RPs compared with the ENs/NAs. The majority of the ENs/NAs stated Do not know on many items concerning attitudes towards research, support for research utilization and actual use of research.

Conclusions.  Despite overall positive attitudes towards research, the majority of staff did not use research findings in daily practice. This was particularly valid for the EN/NA group.

Relevance to clinical practice.  There is an urgent need for managers and others in the care of older people to develop strategies for implementing evidence‐based practice that involves the EN/NA group.
Discharging older people from hospital to home: what do we know?
Authors: Coffey Alice
Published: August 2006

Aims and objectives.  The aim of this literature review was to examine empirical research to date on hospital discharge and illuminate areas in need of further exploration.

Background.  Discharging older people from hospital has long been associated with difficulties and complications. With a steady increase in the ageing population in Ireland and their use of acute hospital services, the successful management of hospital discharge is now a central concern to health service management.

Methods.  Using a seven‐step approach by Stolz et al. [Scandinavian Journal of Caring Sciences (2004) Vol. 18, 111–119] a keyword database search was conducted which revealed 44 studies that matched the author's inclusion criteria.

Results.  These studies uncover aspects of the discharge process that are in need of further research, and particularly suggest more rigour in the measurement of hospital discharge outcomes.

Relevance to clinical practice.  This review focuses on a very important clinical issue given the predicted increase in the use of acute services by older people and the known vulnerabilities of the interface between hospital and community settings.
The risk to enduring relationships following the move to a care home
Authors: Cook Glenda
Published: August 2006

Aim.  To explore findings from a study which investigated the meanings that older people attributed to their experiences of living in a care home and consequently the risks that they identify in this.

Background.  There is evidence from this and other studies that being able to engage in long‐time friendships is important to older people. The move to a care home has the potential to disrupt these relationships and there is a risk of breakdown of the friendships that have been valued throughout life.

Method.  A hermeneutic inquiry that explored the meaning that eight older people ascribed to their life in the care home. This paper focuses on the narratives that concerned relationships with long‐time friends and the risks to these relationships.

Results.  The paper highlights the importance of engaging in meaningful relationships with other people. The participant's stories illuminated the importance of maintaining friendships following the move to a care home and how these had had a positive impact on their lives in that setting. With advancing age and increasing frailty the participants were acutely aware that their friendships were vulnerable to breakdown and they implemented a range of strategies to sustain their relationships with these people.

Conclusion.  The findings point to the importance of acknowledging the value of long‐time friendships to older people and the need to support them in their efforts to sustain these relationships and reduce risks to them.
Risk factors for elder abuse and neglect: brief descriptions of different scenarios in South Africa
Authors: Marais Sandra , Conradie Gerna , Kritzinger Andrienetta
Published: August 2006

Aim.  To describe various situations in which older people in South Africa are vulnerable.

Background.  Poverty compromises the health of many older people in South Africa but the circumstances and ways in which this is managed and risk thought of is poorly understood. This paper presents three scenarios that describe individual studies and provide insight into the factors influencing the lives of some older people.

Method.  Scenario 1 concerns people with dementia. Pilot work has collected interview data from four people with dementia, their four informal carers and three hospital nursing staff.

Scenario 2 concerns an analysis of data collected routinely as part of the Halt Elder Abuse Line, a telephone‐based service for people to report abuse.

Scenario 3 concerns an interview study with farm workers who have retired and who are vulnerable to being displaced from the farms.

Conclusion.  A variety of policy, social and individual factors result in older people being vulnerable and continuing research is required to further develop an understanding of these dynamics of risk to promote changes to current policy and practices.
Older people's experience of participating in a reminiscence group with a gerotranscendental perspective: reminiscence group with a gerotranscendental perspective in practice
Authors: Wadensten Barbro , Hägglund Doris
Published: August 2006

Tornstam's theory of gerotranscendence provides the theoretical underpinning for two small reminiscence groups that met for eight weekly sessions in a Swedish daycentre. Tornstams's theoretical perspective provides a developmental model for understanding positive progressive changes in values, attitudes and behaviour in the second half of life. Practical guidelines derived from this theory informed the group‐work approach used. Participants’ opinions about their reminiscence experience were analysed to determine the relevance of gerotranscendental theory as a basis for understanding older people's use of reminiscence in the ageing process. The study aimed at investigating older peoples’ experiences of participating in a reminiscence group with a gerotranscendental perspective. The study used a qualitative approach. Older people were invited to participate in reminiscence group sessions arranged at a daycentre. When the sessions were finished, participants were interviewed about their experience of the reminiscence group. Data were analysed and categorized by using qualitative methods. The participants were satisfied with the arrangement of the group sessions. All participants believed they had reminisced and thought much more about their childhood and also recalled other memories from their lives during the period. Three quite different views emerged of the recall experience and effects of participating in the reminiscence group: ‘An activity like any other; an activity that led to thoughts about memories from life or an activity that influenced my thoughts about life.’ Findings suggest that it is possible to arrange reminiscence groups from a gerotranscendental perspective that serve as an intervention in gerontological nursing. This paper provides some guidance concerning how this type of group may be arranged and the various categories of participant response that may be expected.
Comparative Analysis of Tooth-Root Strength Using ISO and AGMA Standards in Spur and Helical Gears With FEM-based Verification
Authors: Kawalec Andrzej , Wiktor Jerzy , Ceglarek Dariusz
Published: August 2006

Current trends in engineering globalization require researchers to revisit various normalized standards that determine “best practices” in industries. This paper presents comparative analysis of tooth-root strength evaluation methods used within ISO and AGMA standards and verifying them with developed models and simulations using the finite element method (FEM). The presented analysis is conducted for (1) wide range of spur and helical gears manufactured using racks or gear tools; and for (2) various combinations of key geometrical (gear design), manufacturing (racks and gear tools), and performance (load location) parameters. FEM of tooth-root strength is performed for each modeled gear. FEM results are compared with stresses calculated based on the ISO and AGMA standards. The comparative analysis for various combinations of design, manufacturing, and performance parameters are illustrated graphically and discussed briefly. The results will allow for a better understanding of existing limitations in the current standards applied in engineering practice as well as provide a basis for future improvements and/or unifications of gear standards.
Effect of the Wheel Geometric Design on the Nonlinear Dynamics of Railroad Vehicles
Authors: Shabana Ahmed A. , Tobaa Mahmoud , Zaazaa Khaled E.
Published: August 2006

The effect of the geometry of a wheel profile that allows only a single point of contact with the rail is investigated in this study. The local geometric properties of this profile are compared with the local geometric properties of a profile that allows for two-point contacts in order to understand the basic differences between the two profiles. A simple model is first used to examine the effect of the profile geometry on the stability and nonlinear dynamics of a suspended wheel set. The results obtained using this simple model show that the geometry of the wheel profile can significantly alter the critical speed. A computational approach is then used to investigate and quantify the effect of the wheel geometry wheel on the dynamics and stability of railroad vehicles. Two methods, the contact constraint and elastic formulations, are used. The contact constraint method employs nonlinear algebraic kinematic constraint equations to describe the contact between the wheel and the rail. The contact kinematic constraints, which eliminate one degree of freedom and do not allow for wheel/rail separation, are imposed at the position, velocity and acceleration levels. The system equations of motion are expressed in terms of the generalized coordinates and the nongeneralized surface parameters. In the formulations based on the elastic approach, the wheel has six degrees of freedom with respect to the rail, and the normal contact forces are defined as a function of the penetration using Hertz’s contact theory or using assumed stiffness and damping coefficients. In the elastic approach that allows for wheel/rail separation, the locations of the contact points are determined by solving a set of algebraic equations. The distribution of the contact forces resulting from the use of the two profiles that have different geometric properties is investigated using the two methods. Numerical results are presented for a full railroad vehicle model and the effect of the wheel profile on the vehicle stability is investigated.
The Mechanisms by Which Adaptive One-factor-at-a-time Experimentation Leads to Improvement
Authors: Frey Daniel D. , Jugulum Rajesh
Published: August 2006

This paper examines mechanisms underlying the phenomenon that, under some conditions, adaptive one-factor-at-a-time experiments outperform fractional factorial experiments in improving the performance of mechanical engineering systems. Five case studies are presented, each based on data from previously published full factorial physical experiments at two levels. Computer simulations of adaptive one-factor-at-a-time and fractional factorial experiments were carried out with varying degrees of pseudo-random error. For each of the five case studies, the average outcomes are plotted for both approaches as a function of the strength of the pseudo-random error. The main effects and interactions of the experimental factors in each system are presented and analyzed to illustrate how the observed simulation results arise. The case studies show that, for certain arrangements of main effects and interactions, adaptive one-factor-at-a-time experiments exploit interactions with high probability despite the fact that these designs lack the resolution to estimate interactions. Generalizing from the case studies, four mechanisms are described and the conditions are stipulated under which these mechanisms act.
Kinematic, Static, and Dynamic Analysis of a Spatial Three-Degree-of-Freedom Tensegrity Mechanism
Authors: Arsenault Marc , Gosselin Clément M.
Published: August 2006

One of the drawbacks of conventional mechanisms is the significant inertia of their moving parts. Tensegrity mechanisms, which have a reduced mass because of their extensive use of cables and springs, represent a potential alternative to these mechanisms for certain types of applications. In this paper a new spatial three-degree-of-freedom tensegrity mechanism is developed and analyzed. Mathematical models of the kinematics, statics, and dynamics of the mechanism are generated. These models reveal several characteristics of the fundamental behavior of tensegrity mechanisms that make them rather unique.
Design of a Compliant Mechanism to Modify an Actuator Characteristic
to Deliver a Constant Output Force
Authors: Pedersen C. B. W. , Fleck N. A. , Ananthasuresh G. K.
Published: August 2006

Topology and size optimization methods are used to design compliant mechanisms that produce a constant output force for a given actuator characteristic of linearly decreasing force versus displacement. The design procedure consists of two stages: (i) topology optimization using two-dimensional (2-D) continuum parametrization, and (ii) size optimization of the beam-element abstraction derived from the continuum topology solution. The examples considered are based upon electrostatic microactuators used widely in microsystems. The procedure described here provides conceptual as well as practically usable designs for compliant transmission mechanisms with a constant output force characteristic. For any given topology design, the maximum achievable constant force over a given displacement range is determined. Ideal rigid-body and spring-equipped mechanisms are analyzed and their features are used to compare with the compliant solutions obtained.
Long-Distance Dispersal of Plants
Authors: Nathan Ran
Published: August 2006

Long-distance dispersal (LDD) of plants poses challenges to research because it involves rare events driven by complex and highly stochastic processes. The current surge of renewed interest in LDD, motivated by growing recognition of its critical importance for natural populations and communities and for humanity, promises an improved, quantitatively derived understanding of LDD. To gain deep insights into the patterns, mechanisms, causes, and consequences of LDD, we must look beyond the standard dispersal vectors and the mean trend of the distribution of dispersal distances. “Nonstandard” mechanisms such as extreme climatic events and generalized LDD vectors seem to hold the greatest explanatory power for the drastic deviations from the mean trend, deviations that make the nearly impossible LDD a reality.