bluuebunny/crossref_metadata_2025 huggingface dataset:
Modelization of the fragmentation dynamics of krypton clusters (Krn,n=2–11) following electron impact ionization
Authors: Bonhommeau David , Bouissou Thomas , Halberstadt Nadine , Viel Alexandra
Published: April 2006

We present the first prediction for the fragmentation dynamics following electron impact ionization of neutral krypton clusters from 2 to 11 atoms. Fragment proportions and parent ion lifetimes are deduced from a molecular dynamics with quantum transitions study in which the nuclei are treated classically and the transitions between electronic states quantum mechanically. The potential-energy surfaces are derived from a diatomics-in-molecules model to which induced dipole-induced dipole and spin-orbit interactions are added. The results show surprisingly fast and extensive fragmentation for clusters of such a heavy atom, although not as extensive as in the case of neon clusters studied previously [D. Bonhommeau et al., J. Chem. Phys. 123, 54316 (2005)]. The parent ion lifetimes range from 2.8to0.7ps, and the most abundant fragment is Kr2+ for all studied sizes, followed by Kr+ for sizes smaller than 7 atoms and by Kr3+ for larger sizes. Trimer and larger fragments are found to originate from the lower electronic states of parent ions. The comparison with preliminary results from experiments on size-selected neutral clusters conducted by Steinbach et al. (private communication) reveal a good agreement on the extensive character of the fragmentation. It is checked that the additional internal energy brought by the helium scattering technique used for size selection does not affect the fragment proportions. In addition, the existence of long-lived trajectories is revealed, and they are found to be more and more important for larger cluster sizes and to favor the stabilization of larger fragments. The implications of this work for microsecond-scale dynamics of ionized rare-gas clusters are discussed. In particular, given the extent of fragmentation of the parent clusters and the fast kinetics of the whole process, the small cluster ions that exhibit a monomer loss in the microsecond time window must originate from much larger neutral precursors. The decay rate of the II(1∕2)u state of the ionic dimer Kr2+ by spin-orbit coupling is found to be of the order of 3ps, in contrast to the expected tens of microseconds, but only reasonably faster than the corresponding state of HeNe+. Finally, the spin-orbit interaction strongly affects both the Kr+∕Kr2+ ratio and some of the characteristic times of the dynamics, especially for smaller sizes, but not the overall dependence of the fragment proportions as a function of cluster size.
High dielectric and nonlinear electrical behaviors in TiO2-rich CaCu3Ti4O12 ceramics
Authors: Lin Yuan-Hua , Cai Jingnan , Li Ming , Nan Ce-Wen , He Jinliang
Published: April 2006

We present a TiO2-rich CaCu3Ti4O12 polycrystalline ceramic with high dielectric and nonlinear electrical properties. Analysis of the ceramic microstructure and composition indicates that obvious grain boundaries are formed. Our results demonstrate that all the ceramic samples exhibit high dielectric permittivity and remain almost constant over the frequency range from 100Hzto1MHz, which could be attributed to an internal boundary layer capacitance effect. The current-density–electric-field characteristics prove that the excessive TiO2 in the CaCu3Ti4O12 ceramics can efficiently improve varistor voltage and nonlinear coefficient.
Ferroelectric and reliability properties of metal-organic chemical vapor deposited Pb(Zr0.15Ti0.85)O3 thin films grown in the self-regulation process window
Authors: Zhao Jin Shi , Lee Hyun Ju , Sim Joon Seop , Lee Keun , Hwang Cheol Seong
Published: April 2006

Ferroelectric reliability of Pb(Zr0.15Ti0.85)O3 films grown by metal-organic chemical vapor deposition at 570°C on an Ir electrode in the self-regulation process window [constant Pb concentration irrespective of the precursor input ratio (Pb∕(Zr+Ti), PIR)] was studied. Although the Pb composition and crystallinity of the films grown under different PIR were almost identical, the film grown under a PIR which was near the center of the process window showed the best ferroelectric performance. X-ray photoelectron spectroscopy showed that the films grown at lower and higher PIR have residual ZrO2 and metallic Pb, respectively, which resulted in reduced remanent polarization and reliability.
Thermodynamic modeling of glass formation in metallic glasses
Authors: Xia L. , Fang S. S. , Wang Q. , Dong Y. D. , Liu C. T.
Published: April 2006

In the study of metallic glasses, it is vitally important for us to understand glass formation and glass forming ability (GFA). This letter presents a thermodynamic model for evaluating glass formation in metallic glasses. An expression has been derived from considering both the stability of amorphous phases and the resistance to the formation of crystalline intermetallic phases. This equation is very useful for identifying alloy compositions with good GFA in binary and other alloy systems. The prediction of this equation has been verified by the experimental study of glass formation and glass forming ability in the Zr–Cu system.
Comparing Migration in Britain and Australia: Harmonisation through Use of Age–Time Plans
Authors: Bell Martin , Rees Philip
Published: April 2006

Differences in the way migration is measured impede cross-national comparisons of internal migration. In this paper we utilise age–time diagrams to elucidate these problems for Australia and the United Kingdom and present solutions which generate time series of interregional migration for the two countries, harmonised with respect to age–time plans. We achieve this through estimation of the numbers of migration transitions (Australia) or migration events (Britain) for common age–period–cohort (APC) spaces. We derive appropriate population stocks for computation of transition probabilities or occurrence-exposure rates. In the final section of the paper we present a series of migration-intensity calculations based on varying combinations of period–cohort, period–age, and age–period–cohort perspectives, to demonstrate the significance of the variations, and the errors that can arise without harmonisation.
Every Breath You Take? Environmental Justice and Air Pollution in Christchurch, New Zealand
Authors: Pearce Jamie , Kingham Simon , Zawar-Reza Peyman
Published: April 2006

In a number of environmental-justice studies it has been noted that the exposure to an array of air pollutants varies between different social groups. This inequality in exposure is one possible explanation for the variations in pollution-related health outcomes such as lung cancer and other respiratory diseases. Previous environmental-justice studies that have focused upon air pollution have tended to be concerned with exposure to industrial and vehicle pollution and rely upon simple estimates of exposure, ignoring the complex interaction of emissions, topography, and meteorology that determine pollution levels in many urban areas. In this paper we use accurate and geographically detailed estimates of pollution calculated from an atmospheric dispersion model to examine issues of environmental justice related to air pollution sourced from domestic heating in Christchurch, New Zealand, a city with particularly high levels of particulate pollution during winter months. We consider whether there is a social gradient in exposure to air pollution in Christchurch by comparing estimates of particulate pollution for small areas across the city to a range of demographic and socioeconomic indicators including age, ethnicity, income, and deprivation. Furthermore, we examine whether there is a social gradient in exposure to extreme pollution episodes. We demonstrate that different social groups in the Christchurch population are exposed to different levels of both ambient air pollution and extreme air-pollution episodes. In particular, pollution is significantly higher among more disadvantaged communities. We also find evidence which suggests that the groups responsible for producing a large proportion of the pollution in Christchurch are not the same groups exposed to high levels of particulate air pollution.
Estrogen transactivates EGFR via the sphingosine 1-phosphate receptor Edg-3: the role of sphingosine kinase-1
Authors: Sukocheva Olga , Wadham Carol , Holmes Andrew , Albanese Nathaniel , Verrier Emily , Feng Feng , Bernal Alex , Derian Claudia K. , Ullrich Axel , Vadas Mathew A. , Xia Pu
Published: April 2006

The transactivation of enhanced growth factor receptor (EGFR) by G protein–coupled receptor (GPCR) ligands is recognized as an important signaling mechanism in the regulation of complex biological processes, such as cancer development. Estrogen (E2), which is a steroid hormone that is intimately implicated in breast cancer, has also been suggested to function via EGFR transactivation. In this study, we demonstrate that E2-induced EGFR transactivation in human breast cancer cells is driven via a novel signaling system controlled by the lipid kinase sphingosine kinase-1 (SphK1). We show that E2 stimulates SphK1 activation and the release of sphingosine 1-phosphate (S1P), by which E2 is capable of activating the S1P receptor Edg-3, resulting in the EGFR transactivation in a matrix metalloprotease–dependent manner. Thus, these findings reveal a key role for SphK1 in the coupling of the signals between three membrane-spanning events induced by E2, S1P, and EGF. They also suggest a new signal transduction model across three individual ligand-receptor systems, i.e., “criss-cross” transactivation.
A kinase-deficient TrkC receptor isoform activates Arf6–Rac1 signaling through the scaffold protein tamalin
Authors: Esteban Pedro F. , Yoon Hye-Young , Becker Jodi , Dorsey Susan G. , Caprari Paola , Palko Mary Ellen , Coppola Vincenzo , Saragovi H. Uri , Randazzo Paul A. , Tessarollo Lino
Published: April 2006

Neurotrophins play an essential role in mammalian development. Most of their functions have been attributed to activation of the kinase-active Trk receptors and the p75 neurotrophin receptor. Truncated Trk receptor isoforms lacking the kinase domain are abundantly expressed during development and in the adult; however, their function and signaling capacity is largely unknown. We show that the neurotrophin-3 (NT3) TrkCT1-truncated receptor binds to the scaffold protein tamalin in a ligand-dependent manner. Moreover, NT3 initiation of this complex leads to activation of the Rac1 GTPase through adenosine diphosphate-ribosylation factor 6 (Arf6). At the cellular level, NT3 binding to TrkCT1–tamalin induces Arf6 translocation to the membrane, which in turn causes membrane ruffling and the formation of cellular protrusions. Thus, our data identify a new signaling pathway elicited by the kinase-deficient TrkCT1 receptor. Moreover, we establish NT3 as an upstream regulator of Arf6.
The secretory membrane system in the Drosophila syncytial blastoderm embryo exists as functionally compartmentalized units around individual nuclei
Authors: Frescas David , Mavrakis Manos , Lorenz Holger , DeLotto Robert , Lippincott-Schwartz Jennifer
Published: April 2006

Drosophila melanogaster embryogenesis begins with 13 nuclear division cycles within a syncytium. This produces >6,000 nuclei that, during the next division cycle, become encased in plasma membrane in the process known as cellularization. In this study, we investigate how the secretory membrane system becomes equally apportioned among the thousands of syncytial nuclei in preparation for cellularization. Upon nuclear arrival at the cortex, the endoplasmic reticulum (ER) and Golgi were found to segregate among nuclei, with each nucleus becoming surrounded by a single ER/Golgi membrane system separate from adjacent ones. The nuclear-associated units of ER and Golgi across the syncytial blastoderm produced secretory products that were delivered to the plasma membrane in a spatially restricted fashion across the embryo. This occurred in the absence of plasma membrane boundaries between nuclei and was dependent on centrosome-derived microtubules. The emergence of secretory membranes that compartmentalized around individual nuclei in the syncytial blastoderm is likely to ensure that secretory organelles are equivalently partitioned among nuclei at cellularization and could play an important role in the establishment of localized gene and protein expression patterns within the early embryo.
Soluble Mediators, Not Cilia, Determine Airway Surface Liquid Volume in Normal and Cystic Fibrosis Superficial Airway Epithelia
Authors: Tarran Robert , Trout Laura , Donaldson Scott H. , Boucher Richard C.
Published: April 2006

A key aspect of the lung's innate defense system is the ability of the superficial epithelium to regulate airway surface liquid (ASL) volume to maintain a 7-μm periciliary liquid layer (PCL), which is required for cilia to beat and produce mucus flow. The mechanisms whereby airway epithelia regulate ASL height to ≥7 μm are poorly understood. Using bumetanide as an inhibitor of Cl− secretion, and nystatin as an activator of Na+ absorption, we found that a coordinated “blending” of both Cl− secretion and Na+ absorption must occur to effect ASL volume homeostasis. We then investigated how ASL volume status is regulated by the underlying epithelia. Cilia were not critical to this process as (a) ASL volume was normal in cultures from patients with primary ciliary dyskinesia with immotile cilia, and (b) in normal cultures that had not yet undergone ciliogenesis. However, we found that maneuvers that mimic deposition of excess ASL onto the proximal airways, which occurs during mucociliary clearance and after glandular secretion, acutely stimulated Na+ absorption, suggesting that volume regulation was sensitive to changes in concentrations of soluble mediators in the ASL rather than alterations in ciliary beating. To investigate this hypothesis further, we added potential “soluble mediators” to the ASL. ASL volume regulation was sensitive to a channel-activating protein (CAP; trypsin) and a CAP inhibitor (aprotinin), which regulated Na+ absorption via changes in epithelial Na+ channel (ENaC) activity in both normal and cystic fibrosis cultures. ATP was also found to acutely regulate ASL volume by inducing secretion in normal and cystic fibrosis (CF) cultures, while its metabolite adenosine (ADO) evoked secretion in normal cultures but stimulated absorption in CF cultures. Interestingly, the amount of ASL/Cl− secretion elicited by ATP/ADO was influenced by the level of CAP-induced Na+ absorption, suggesting that there are important interactions between the soluble regulators which finely tune ASL volume.
Feedback Network Controls Photoreceptor Output at the Layer of First Visual Synapses in Drosophila
Authors: Zheng Lei , de Polavieja Gonzalo G. , Wolfram Verena , Asyali Musa H. , Hardie Roger C. , Juusola Mikko
Published: April 2006

At the layer of first visual synapses, information from photoreceptors is processed and transmitted towards the brain. In fly compound eye, output from photoreceptors (R1–R6) that share the same visual field is pooled and transmitted via histaminergic synapses to two classes of interneuron, large monopolar cells (LMCs) and amacrine cells (ACs). The interneurons also feed back to photoreceptor terminals via numerous ligand-gated synapses, yet the significance of these connections has remained a mystery. We investigated the role of feedback synapses by comparing intracellular responses of photoreceptors and LMCs in wild-type Drosophila and in synaptic mutants, to light and current pulses and to naturalistic light stimuli. The recordings were further subjected to rigorous statistical and information-theoretical analysis. We show that the feedback synapses form a negative feedback loop that controls the speed and amplitude of photoreceptor responses and hence the quality of the transmitted signals. These results highlight the benefits of feedback synapses for neural information processing, and suggest that similar coding strategies could be used in other nervous systems.
Teaching in the Spirit of Socrates: Remembering Fergal O’Connor OP
Authors: Dunne Joseph
Published: April 2006

(The late Father Fergal O’Connor OP was born near Causeway, Co. Kerry, on 6 December 1926 and died in Dublin on 29 September 2005. Having studied at St. Mary's Tallaght, he was ordained a priest in 1951. He took the STD at the Angelicum in Rome in 1955 and then went on to take PPE at Oxford, staying at Blackfriars from 1956 to 1959. Having taught for a short time at the Dominican House at Cork, he was assigned to St. Saviour's Priory in Dublin in 1961, where he lived for the rest of his life. From 1962 he taught political philosophy at University College Dublin, continuing beyond retirement in 1991 to teach a course on Plato until 1997. A social critic and activist, he was for many years a provocative panelist on Ireland's foremost television programme, ‘The Late Late Show’, and wrote regularly for newspapers and periodicals; also he founded and for several decades directed Sherrard House, a hostel for homeless girls in Dublin, and ALLY, an organisation supporting single mothers. But it was as an extraordinarily inspiring teacher, primarily in the university but also in many other informal settings, that he was perhaps most deeply influential. The following is a slightly amended version of an article first published in Questioning Ireland, Debates in Political Philosophy and Public Policy (eds, J. Dunne, A. Ingram and F.Litton, Dublin, IPA), a Festschrift for Father O’Connor written by former students and colleagues (including the theologian, Denys Turner, and the political philosopher, Philip Pettit) and published in 2000.)
Treatment of severe aplastic anaemia with combined immunosuppression: anti‐thymocyte globulin, ciclosporin and mycophenolate mofetil
Authors: Scheinberg Phillip , Nunez Olga , Wu Colin , Young Neal S.
Published: April 2006

Severe aplastic anaemia (SAA) can be successfully treated with immunosuppressive therapies or haematopoietic stem cell transplantation (HSCT). Response rates with horse anti‐thymocyte globulin (h‐ATG) plus ciclosporin (CsA) are about 60–70%, and robust responders have an excellent long‐term survival. We introduced a third immunosuppressive agent to standard h‐ATG/CsA, mycophenolate mofetil (MMF), in an attempt to improve the response rate and survival, and to decrease the relapse rate and clonal evolution to myelodysplasia. A total of 104 consecutive patients with SAA were treated with h‐ATG/CsA/MMF between May 1999 and June 2003 at the National Institutes of Health Clinical Center. The overall response rate at 6 months was 62%, with 24 (37% of responders) patients relapsing at a median of 389 d from ATG. Nine patients showed evidence of clonal evolution following ATG. After a median follow up of 42 months, the median survival among responders was not reached and among non‐responders was 58 months. Over half of the relapses occurred during MMF administration. Despite a strong theoretical rationale for its use, MMF did not result in the improvement of response or relapse rates when compared with historical standard h‐ATG/CsA.
Effects of human γ‐globin in murine β‐thalassaemia
Authors: Nishino Tamon , Cao Hua , Stamatoyannopoulos George , Emery David W.
Published: April 2006

Murine models of β‐thalassaemia have been used to test therapeutic globin gene vectors. However, the level of γ‐globin expression necessary to achieve full phenotypic correction in these models is unclear. In order to address this issue, we carried out breeding and transplantation studies in murine models of β‐thalassaemia intermedia (Hbbth−3/+) and severe β‐thalassaemia major (Hbbth−3/Hbbth−3) using transgenic lines expressing various levels of human γ‐globin. Expression of γ‐globin RNA at a modest 7–14% of total α‐globin RNA resulted in the selective survival of HbF(+) erythrocytes, a fivefold increase in total HbF, and a phenotypic improvement in the β‐thalassaemia intermedia model. Full normalisation of erythrocyte indices in this model required γ‐globin RNA expression at 27% of α‐globin, resulting in an average 40% (6·8 g/dl) HbF. Studies using the homozygous Hbbth−3 model of lethal β‐thalassaemia major demonstrated that even this high level of γ‐globin expression, for reasons related to the function of the hybrid globin tetramers, could only prolong, but not fully support, survival. Taken together, these results indicate that only the heterozygous Hbbth−3 model of β‐thalassaemia intermedia can be reliably used for the pre‐clinical assessment of γ‐globin gene therapy vectors, as well as other means of γ‐globin gene induction.
Comparative study of validity of clinical, X‐ray and magnetic resonance imaging scores in evaluation and management of haemophilic arthropathy in children
Authors: PERGANTOU H. , MATSINOS G. , PAPADOPOULOS A. , PLATOKOUKI H. , ARONIS S.
Published: April 2006

Summary.  To evaluate joints alterations, we performed clinical examination, X‐rays and magnetic resonance imaging (MRI) (Denver score) in 165 joints of 40 children with severe (n, 32) or moderate (n, 8) haemophilia A or B. All investigated joints had a history of more than three bleeds. At evaluation, 25 of 40 haemophilic patients were on prophylaxis for the last 1–8 years (mean: 3.5 years). MRI revealed chronic synovitis in 55.4% and 50% of joints, which were diagnosed, as normal by the clinical scale and plain radiography respectively. Moreover, MRI unmasked more profound alterations than those observed by plain radiography in 70% of cases. Statistical analysis showed that the clinical and Pettersson scores in contrast to the Denver score provide an underestimation of arthritic changes. Besides, Denver score did not provide resolution in differentiating stages of arthropathy, because of its inherent nature; however, a score of 6 expressing severe synovitis seemed to be the cut‐off value for the distinction of severe cases. Based on MRI findings we intensified prophylaxis in nine children and initiated it in another nine children. Five children, who were already on prophylaxis complied with our recommendations and eliminated haemorrhages. Finally, three boys with severe haemophilic arthropathy in knees underwent successful chemical synovectomy with rifampicin.
Failure of rituximab to induce immune tolerance in a boy with severe haemophilia A and an alloimmune factor VIII antibody: a case report and review of the literature
Authors: BISS T. T. , VELANGI M. R. , HANLEY J. P.
Published: April 2006

Summary. We report the use of rituximab (MabThera®; Roche Grenzach‐Wyhlen, Germany) in a 6‐year‐old boy with severe haemophilia A and a high titre alloimmune factor VIII (FVIII) antibody, which had failed to respond to standard immune tolerance therapy. Rituximab was administered in 4 weekly doses with concurrent high‐dose i.v. immunoglobulin (Flebogamma®; Grifols, Barcelona, Spain) followed by daily high‐dose recombinant FVIII concentrate (Recombinate®; Baxter, CA, USA). Despite a fall in CD20 positive cell count to undetectable levels the inhibitor persisted. We discuss the possible reasons for failure of immune tolerance induction and review the literature concerning the use of rituximab for this indication.
Shaping ability of the M4 handpiece and Safety Hedstrom Files in simulated root canals
Authors: LLOYD A. , JAUNBERZINS A. , DHOPATKAR A. , BRYANT S. , DUMMER P. M. H.
Published: April 2006

The aim of this study was to assess the shaping ability of the M4 reciprocating handpiece and Safety Hedstrom files in simulated canals. A total of 40 simulated canals of various angles and positions of curvature were prepared with an M4 handpiece using Safety Hedstrom files oriented with the ground, flattened surface towards the inner aspect of the curve. A standard regimen was adopted throughout. Pre‐ and post‐operative longitudinal images of the canals were taken with a video camera and stored and manipulated in a computer with image analysis software. The presence of canal aberrations and the amount and location of resin material removed as a result of preparation were determined from composite images of superimposed pre‐ and post‐operative views.

Preparation time varied significantly (P<0.001) between the canal types; overall, 20° canals were prepared more quickly than 40° canals. Zips and elbows were observed in 16 out of the 40 canals with most (11) being created in 40° specimens. Ledges were found in 19 canals and perforations in only 1. There were no significant differences between canal shapes for these aberrations.

Excessive removal of material from the inner aspect of the canal at the curve to create a danger zone was found in 20 canals, but only in those with 40° curves. Significant differences in total canal width between the canal types were seen at the zips (P<0.05), elbows (P<0.05) and danger zones (P<0.001). Transportation at the danger zones varied significantly (P<0.001) between canal types.

Under the conditions of this study, the M4 handpiece and Safety Hedstrom files created hour‐glass preparations in a substantial proportion of canals. In reality, the Safety Hedstrom file with its one flattened surface was ineffective at reducing removal of material along the inner aspect of canal curves in severely curved specimens and clearly has the potential to create strip perforations in teeth.
Cloning of rhesus monkey LILRs*
Authors: Slukvin I.I. , Grendell R.L. , Rao D.S. , Hughes A.L. , Golos T.G.
Published: April 2006

Leukocyte Ig‐like receptors (LILRs) are a family of receptors that have inhibitory and activating functions and widely expressed by lymphoid and myeloid cells. Here we report the identification of the rhesus monkey LILRs by screening of rhesus spleen and decidua cDNA libraries and RT‐PCR cloning. We obtained eight different full‐length clones with structural and functional diversity similar to human LILRs, including LILRs with immunoreceptor tyrosine‐based inhibitory motifs, LILRs with truncated cytoplasmic tails containing positively charged arginine residues in the transmembrane domain, and putative soluble receptors lacking transmembrane or cytoplasmic domains. Characterization of rhesus LILRs will facilitate use of this non‐human primate model for the study of the functional role(s) of LILRs, including immune regulation through interaction with non‐classical MHC class I molecules.
ON HIGH‐SKILL AND LOW‐SKILL EQUILIBRIA: A MARKOV CHAIN APPROACH
Authors: Lavezzi Andrea Mario
Published: April 2006

In this paper we propose to study the dynamics of human capital accumulation by means of a Markov chain. We identify the conditions for the emergence of ergodic and nonergodic dynamics, and relate them to various characteristics of an economic system. The model may generate high‐skill and low‐skill equilibria as well as intermediate situations. Policy implications are also discussed.
An Assessment of the Disorderly Adjustment Hypothesis for Industrial Economies*
Authors: Croke Hilary , Kamin Steven B. , Leduc Sylvain
Published: April 2006

Much has been written about prospects for US current account adjustment, including the possibility of what is sometimes referred to as a ‘disorderly correction’: a sharp fall in the exchange rate that boosts interest rates, depresses stock prices and weakens economic activity. This paper assesses some of the empirical evidence bearing on the plausibility of the disorderly adjustment scenario, drawing on the experience of previous current account adjustments in industrial economies. We examined the paths of key economic performance indicators before, during and after the onset of adjustment, building on the analysis of Freund (2000).

We found little evidence among past adjustment episodes of the features highlighted by the disorderly adjustment hypothesis. Although some episodes in our sample experienced significant shortfalls in GDP growth after the onset of adjustment, these shortfalls were not associated with significant and sustained depreciations of real exchange rates, increases in real interest rates or declines in real stock prices. By contrast, it was among the episodes where GDP growth picked up during adjustment that the most substantial depreciations of real exchange rates occurred. These findings do not preclude the possibility that future current account adjustments could be disruptive, but they weaken the historical basis for predicting such an outcome.
Applying Network Analysis to the Conservation of Habitat Trees in Urban Environments: a Case Study from Brisbane, Australia
Authors: RHODES MONIKA , WARDELL‐JOHNSON GRANT W. , RHODES MARTIN P. , RAYMOND BEN
Published: April 2006

Abstract:  In Australia more than 300 vertebrates, including 43 insectivorous bat species, depend on hollows in habitat trees for shelter, with many species using a network of multiple trees as roosts. We used roost‐switching data on white‐striped freetail bats (Tadarida australis; Microchiroptera: Molossidae) to construct a network representation of day roosts in suburban Brisbane, Australia. Bats were caught from a communal roost tree with a roosting group of several hundred individuals and released with transmitters. Each roost used by the bats represented a node in the network, and the movements of bats between roosts formed the links between nodes. Despite differences in gender and reproductive stages, the bats exhibited the same behavior throughout three radiotelemetry periods and over 500 bat days of radio tracking: each roosted in separate roosts, switched roosts very infrequently, and associated with other bats only at the communal roost. This network resembled a scale‐free network in which the distribution of the number of links from each roost followed a power law. Despite being spread over a large geographic area (>200 km2), each roost was connected to others by less than three links. One roost (the hub or communal roost) defined the architecture of the network because it had the most links. That the network showed scale‐free properties has profound implications for the management of the habitat trees of this roosting group. Scale‐free networks provide high tolerance against stochastic events such as random roost removals but are susceptible to the selective removal of hub nodes. Network analysis is a useful tool for understanding the structural organization of habitat tree usage and allows the informed judgment of the relative importance of individual trees and hence the derivation of appropriate management decisions. Conservation planners and managers should emphasize the differential importance of habitat trees and think of them as being analogous to vital service centers in human societies.
Estimating Population Size with Noninvasive Capture‐Mark‐Recapture Data
Authors: PETIT ERIC , VALIERE NATHANIEL
Published: April 2006

Abstract:  Estimating population size of elusive and rare species is challenging. The difficulties in catching such species has triggered the use of samples collected noninvasively, such as feces or hair, from which genetic analysis yields data similar to capture‐mark‐recapture (CMR) data. There are, however, two differences between classical CMR and noninvasive CMR. First, capture and recapture data are gathered over multiple sampling sessions in classical CMR, whereas in noninvasive CMR they can be obtained from a single sampling session. Second, because of genotyping errors and unlike classical CMR, there is no simple relationship between (genetic) marks and individuals in noninvasive CMR. We evaluated, through simulations, the reliability of population size estimates based on noninvasive CMR. For equal sampling efforts, we compared estimates of population size N obtained from accumulation curves, a maximum likelihood, and a Bayesian estimator. For a closed population and without sampling heterogeneity, estimates obtained from noninvasive CMR were as reliable as estimates from classical CMR. The sampling structure (single or multiple session) did not alter the results, the Bayesian estimator in the case of a single sampling session presented the best compromise between low mean squared error and a 95% confidence interval encompassing the parametric value of N in most simulations. Finally, when suitable field and lab protocols were used, genotyping errors did not substantially bias population size estimates (bias < 3.5% in all simulations). The ability to reliably estimate population size from noninvasive samples taken during a single session offers a new and useful technique for the management and conservation of elusive and rare species.
Between‐Meal Risedronate Does Not Alter Bone Turnover in Nursing Home Residents
Authors: Agrawal Sabina , Krueger Diane C. , Engelke Jean A. , Nest Lori J. , Krause Peggy F. , Drinka Paul J. , Binkley Neil C.
Published: April 2006

OBJECTIVES: To assess the effect of between‐meal weekly risedronate and daily calcium 630 mg and vitamin D 400 IU on bone turnover markers.

DESIGN: Randomized,double‐blind,placebo‐controlled trial.

SETTING: Skilled nursing home (NH).

PARTICIPANTS: Sixty skilled‐NH residents (46 men, 14 women), mean age±standard deviation of 76±6, were randomized to receive risedronate 30 mg (n=31) or matching placebo (n=29) once weekly for 12 weeks. All received 315 mg calcium with 200 IU vitamin D twice daily.

MEASUREMENTS: Bone‐specific alkaline phosphatase (BSAP), N‐telopeptide of type 1 collagen (NTx), 25‐hydroxyvitamin D (25OHD), and parathyroid hormone were measured at baseline and 6 and 12 weeks.

RESULTS: Risedronate reduced BSAP significantly more than placebo (P<.05) at 6 weeks but not at 12 weeks; no treatment effect on serum NTx was observed. Defining hypovitaminosis D as a serum 25OHD concentration below 32 ng/mL, 50 of 53 (94%) study participants were low at baseline (mean 25OHD 19 ng/mL). Vitamin D levels remained insufficient in 74% of participants after 12 weeks.

CONCLUSION: In this NH population, weekly risedronate administered using a between‐meal dosing schedule reduced serum BSAP at 6 weeks of treatment; this effect was not observed at 12 weeks. The overall lack of change in bone turnover markers suggests that this risedronate dose and schedule would not be expected to increase bone density or reduce fracture risk in this population. Hypovitaminosis D was common and not reliably corrected by 400 IU of vitamin D daily. Despite an extremely high osteoporotic fracture risk in NH residents, additional study is required to determine under which conditions pharmacological treatment is efficacious in this population and define approaches that assure vitamin D repletion.
Caregiver Characteristics Are Associated with Neuropsychiatric Symptoms of Dementia
Authors: Sink Kaycee M. , Covinsky Kenneth E. , Barnes Deborah E. , Newcomer Robert J. , Yaffe Kristine
Published: April 2006

OBJECTIVES: To determine whether caregiver characteristics are independently associated with neuropsychiatric symptoms of dementia (NPS) after accounting for patient characteristics.

DESIGN: Cross‐sectional analysis of data from the Medicare Alzheimer's Disease Demonstration and Evaluation study.

SETTING: Community‐dwelling residents in eight U.S. cities.

PARTICIPANTS: Five thousand seven hundred eighty‐eight patients with dementia and their caregivers.

MEASUREMENTS: Caregivers were asked about the presence of 12 NPS in patients with dementia. Caregiver predictors included age, sex, education, income, marital status, relationship to the patient, whether they lived with patient, number of hours per week spent caregiving, self‐reported health, dependency in activities of daily living (ADLs) and instrumental activities of daily living (IADLs), depression, and burden. Multivariate linear regression was used to determine which caregiver characteristics were independently associated with reports of more NPS in patients after controlling for the patient's age, sex, dementia severity, level of ADL dependency, and dementia type.

RESULTS: Caregivers were on average 64 years old, 72% female, and 49% were the spouse of the patient (32% wives, 17% husbands). The mean burden score of caregivers was 15 (range 0–32, with higher scores indicating more burden), and 32% had significant depressive symptoms. Patients were on average 79 years old, 60% were female, and most had moderate to severe dementia. The mean number of NPS±standard deviation was 4.8±2.8. After adjusting for patient characteristics, caregivers who were younger, less educated, more depressed, more burdened, or spent more hours per week giving care reported more NPS in care recipients (all P≤.005).

CONCLUSION: Certain caregiver characteristics are associated with NPS, independent of patient characteristics, including dementia severity. Clinicians should consider the dynamics between patients and caregivers when managing NPS. Understanding how different caregiver characteristics influence NPS may help tailor caregiver education and interventions.
Is There Conceptual Convergence in Entrepreneurship Research? A Co–Citation Analysis of Frontiers of Entrepreneurship Research, 1981–2004
Authors: Grégoire Denis A. , Noël Martin X. , Déry Richard , Béchard Jean–Pierre
Published: April 2006

Conceptual convergence is often seen as a holy grail in entrepreneurship research. Yet little empirical research has focused specifically on the extent and nature of this convergence. We address this issue by content–analyzing the networks of co–citation emerging from the 20,184 references listed in the 960 full–length articles published in the Frontiers of Entrepreneurship Research series between 1981 and 2004. Our results provide evidence for the varying levels of convergence that have characterized entrepreneurship research over the years, as well as the evolution of the conceptual themes that have attracted scholars’ attention in different periods. In addition, we provide evidence that the field relies increasingly on its own literature, something that points toward the unique contribution that it makes to the management sciences.
Trends in incidence and survival of mesenchymal neoplasm of the digestive tract within a defined population of Northern Norway
Authors: STEIGEN SONJA ERIKSSON , EIDE TOR J.
Published: April 2006

Population‐based incidence and survival data for gastrointestinal stromal tumor (GIST) are sparse due to the fact that GIST is a rather novel entity both clinically and pathologically, and has not been registered as a separate entity in population‐based cancer registries. The aim of the present study was to reclassify all mesenchymal tumors within a defined population of northern Norway over a time‐span of 30 years with the purpose of estimating trends of incidence and survival. One hundred and forty‐one patients with mesenchymal neoplasms of the digestive tract were identified: 102 as GISTs, 32 as leiomyomatous tumors, 4 as schwannomas, and 3 as fibromas. Incidence rates of GIST showed a significant increase over the whole period, which was not observed for the non‐GIST cases. Analysis of GIST cases showed that cases with more than 5 mitoses per 50 high power fields had an increased expected mortality 4 times that of those with fewer mitoses, and the combination of mitotic count and size of tumor can be recommended for categorizing the tumors into different risk levels. The study confirms that GIST is by far the most frequent mesenchymal neoplasm of the digestive tract and that the incidence has increased over the last 30 years.
RELIABILITY OF LOAD BEARING STEEL PLATES SUBJECTED TO LOCALISED HEAT LOADS
Authors: TEIXEIRA A. P. , GUEDES SOARES C.
Published: April 2006

A reliability formulation is presented for thermally insulated load bearing plates subjected to the localized heat loading. The limit state function is defined in terms of stresses, which account for the additional in-plane compressive loads that the plate will sustain before collapse. The collapse strength of plates is determined with a non-linear finite element code that accounts for the elasto-plastic behavior and for the changes in material properties with temperature. A first order second moment approach is presented to quantify the uncertainty of the heat loads and to describe the importance of the governing variables in the limit state function. An example of the reliability analysis of a steel plate is provided using a time independent first order method.
Current Status of Augmentation and Combination Treatments for Major Depressive Disorder: A Literature Review and a Proposal for a Novel Approach to Improve Practice
Authors: Fava Maurizio , Rush A. John
Published: April 2006

Most patients with major depressive disorder (MDD) do not reach symptom remission. These patients with residual symptoms have worse function and worse prognosis than those who remit. Several augmentation and combination treatments are used to either increase the chances of achieving remission or to eliminate/minimize residual depressive symptoms. Evidence for these pharmacological approaches rests primarily on open, uncontrolled studies, and there are clearly not enough controlled studies. Clinicians should carefully weigh these different treatment options to increase their patients’ chances of achieving and sustaining remission from depression. This paper will review the pertinent studies and will propose a novel approach to improve practice involving the use of augmentation or combination strategies at the outset of initial treatment to primarily enhance the chances of remission through synergy and/or a broader spectrum of action. This novel approach could potentially enhance retention and/or increase remission rates since the lack of response with antidepressant monotherapy may lead many depressed patients with little or no benefit to drop out of treatment, precluding the subsequent use of augmentation or combination strategies altogether. In addition, the emergence of certain side-effects (e.g., agitation, insomnia) or the persistence of some initial baseline symptoms (e.g., anxiety, insomnia) may lead to premature discontinuation from monotherapy in the absence of concomitant use of augmenting pharmacological options targeting these symptoms.
Respiration under Control of Uncoupling Proteins: Clinical Perspective
Authors: Nübel T. , Ricquier D.
Published: April 2006

The term ‘uncoupling protein’ was originally used for the mitochondrial membrane protein UCP1, which is uniquely present in mitochondria of brown adipocytes, thermogenic cells that regulate body temperature in small rodents, hibernators and mammalian newborns. In these cells, UCP1 acts as a proton carrier activated by free fatty acids and creates a shunt between complexes of the respiratory chain and ATP-synthase resulting in a futile proton cycling and dissipation of oxidation energy as heat. Recent identification of new homologues to UCP1 expressed in brown and white adipose tissue, muscle, brain and other tissues together with the hypothesis that these novel uncoupling proteins (UCPs) may regulate thermogenesis and/or fatty acid metabolism and furthermore may protect against free radical oxygen species production have generated considerable optimism for rapid advances in the identification of new targets for pharmacological management of complex pathological syndromes such as obesity, type 2 diabetes or chronic inflammatory diseases. However, since the physiological and biochemical roles of the novel UCPs are not yet clear, the main challenge today consists first of all in providing mechanistic explanation for their functions in cellular physiology. This lively awaited information may be the basis for potential pharmacological targeting of the UCPs in future.
Realizing the Potential of Carotid Artery Stenting
Authors: Roubin Gary S. , Iyer Sriram , Halkin Amir , Vitek Jiri , Brennan Christina
Published: April 2006

Carotid artery stenting, compared with carotid endarterectomy, is emerging as an effective and less invasive method of revascularization for extracranial carotid artery stenosis. Carotid stenting is established as the treatment of choice for certain high-risk patient subsets, and ongoing clinical trials are evaluating this method across a broader clinical spectrum, including asymptomatic patients. For carotid stenting to reach its full potential, an acceptable risk of periprocedural complications, particularly in low-risk patients, must be ensured (the “3% rule”). The present article provides an in-depth review of carotid stenting, with special emphasis on the process of risk stratification pertaining to clinical, anatomic, and procedural considerations necessary to optimize procedural safety and patient outcomes.
Edge Wave Asymmetries
Authors: Panayotova Iordanka N. , Swanson Kyle L.
Published: April 2006

Meridional asymmetry arising from the inclusion of meridional variation in the Coriolis parameter is shown to be a fundamental property of the higher-order dynamics of Eady edge waves. This asymmetry may be relevant to structural characteristics of observed atmospheric transients, particularly short waves propagating along the extratropical dynamic tropopause.
Tropical Cyclone Motion in Response to Land Surface Friction
Authors: Wong Martin L. M. , Chan Johnny C. L.
Published: April 2006

Numerical experiments are performed with the fifth-generation Pennsylvania State University–National Center for Atmospheric Research Mesoscale Model (MM5) to study the effects of surface-moisture flux and friction over land on the movement of tropical cyclones (TCs). On an f plane, the TCs are initially placed 150 km due east of a north–south-oriented coastline in an atmosphere at rest. It is found that a TC could drift toward land when the roughness length is 0.5 m over land, with an average drift speed of ∼1 m s−1. Friction, but not surface-moisture flux over land, is apparently essential for the movement toward land. The friction-induced asymmetry in the large-scale flow is the primary mechanism responsible for causing the TC drift. The mechanism responsible for the development of the large-scale asymmetric flow over the lower to midtroposphere (∼900–600 hPa) appears to be the creation of asymmetric vorticity by the divergence term in the vorticity equation. Horizontal advection then rotates the asymmetric vorticity to give a northeasterly flow in the TC periphery (∼500–1000 km from the TC center). The flow near the TC center has a more northerly component because of the stronger rotation by the tangential wind of the TC at inner radii. However, the TC does not move with the large-scale asymmetric flow. Potential vorticity budget calculations indicate that while the horizontal advection term is basically due to the effect of advection by the large-scale asymmetric flow, the diabatic heating and vertical advection terms have to be considered in determining the vortex landward drift, because of the strong asymmetry in vertical motion. Two mechanisms could induce the asymmetry in vertical motion and cause a deviation of the TC track from the horizontal asymmetric flow. First, the large-scale asymmetric flow in the upper troposphere differs from that in the lower troposphere, both in magnitude and direction, which results in a vertical shear that could force the asymmetry. A vertical tilt of the vortex axis is also found that is consistent with the direction of shear and also the asymmetry in rainfall and vertical motion. Second, asymmetric boundary layer convergence that results from the internal boundary layer could also force an asymmetry in vertical motion.