bluuebunny/crossref_metadata_2025 huggingface dataset:
The cheek plumage patch is an amplifier of dominance in great tits
Authors: Galván Ismael , Sanz Juan José
Published: November 2007

Amplifiers are signals that enhance the perception of other signals or cues, but no studies to date provide empirical evidence for the role of these signals in a reproductive context. Here we use the white cheek patch of great tits as a model for studying this issue. Aggressive interactions decrease patch immaculateness, so patch size may be an amplifier of dominance, that is, more clearly reveal status. If so, in high-quality individuals patch size should correlate positively with reproductive success (here estimated by laying date, assuming that the earlier the better), whereas low-quality individuals with a large patch should only more clearly reveal their low quality and thus suffer low reproductive success, which is exactly the pattern found in males. In contrast, the cheek patch does not seem to function as an amplifier in female great tits.
Novel symptomatology and changing epidemiology of domoic acid toxicosis in California sea lions (
Zalophus californianus
): an increasing risk to marine mammal health
Authors: Goldstein T , Mazet J.A.K , Zabka T.S , Langlois G , Colegrove K.M , Silver M , Bargu S , Van Dolah F , Leighfield T , Conrad P.A , Barakos J , Williams D.C , Dennison S , Haulena M , Gulland F.M.D
Published: November 2007

Harmful algal blooms are increasing worldwide, including those of
Pseudo-nitzschia
spp. producing domoic acid off the California coast. This neurotoxin was first shown to cause mortality of marine mammals in 1998. A decade of monitoring California sea lion (
Zalophus californianus
) health since then has indicated that changes in the symptomatology and epidemiology of domoic acid toxicosis in this species are associated with the increase in toxigenic blooms. Two separate clinical syndromes now exist: acute domoic acid toxicosis as has been previously documented, and a second novel neurological syndrome characterized by epilepsy described here associated with chronic consequences of previous sub-lethal exposure to the toxin. This study indicates that domoic acid causes chronic damage to California sea lions and that these health effects are increasing.
Modelling the mating system of polar bears: a mechanistic approach to the Allee effect
Authors: Molnár Péter K , Derocher Andrew E , Lewis Mark A , Taylor Mitchell K
Published: November 2007

Allee effects may render exploited animal populations extinction prone, but empirical data are often lacking to describe the circumstances leading to an Allee effect. Arbitrary assumptions regarding Allee effects could lead to erroneous management decisions so that predictive modelling approaches are needed that identify the circumstances leading to an Allee effect before such a scenario occurs. We present a predictive approach of Allee effects for polar bears where low population densities, an unpredictable habitat and harvest-depleted male populations result in infrequent mating encounters. We develop a mechanistic model for the polar bear mating system that predicts the proportion of fertilized females at the end of the mating season given population density and operational sex ratio. The model is parametrized using pairing data from Lancaster Sound, Canada, and describes the observed pairing dynamics well. Female mating success is shown to be a nonlinear function of the operational sex ratio, so that a sudden and rapid reproductive collapse could occur if males are severely depleted. The operational sex ratio where an Allee effect is expected is dependent on population density. We focus on the prediction of Allee effects in polar bears but our approach is also applicable to other species.
Sensitivity of managed boreal forests in Finland to climate change, with implications for adaptive management
Authors: Kellomäki Seppo , Peltola Heli , Nuutinen Tuula , Korhonen Kari T , Strandman Harri
Published: November 2007

This study investigated the sensitivity of managed boreal forests to climate change, with consequent needs to adapt the management to climate change. Model simulations representing the Finnish territory between 60 and 70° N showed that climate change may substantially change the dynamics of managed boreal forests in northern Europe. This is especially probable at the northern and southern edges of this forest zone. In the north, forest growth may increase, but the special features of northern forests may be diminished. In the south, climate change may create a suboptimal environment for Norway spruce. Dominance of Scots pine may increase on less fertile sites currently occupied by Norway spruce. Birches may compete with Scots pine even in these sites and the dominance of birches may increase. These changes may reduce the total forest growth locally but, over the whole of Finland, total forest growth may increase by 44%, with an increase of 82% in the potential cutting drain. The choice of appropriate species and reduced rotation length may sustain the productivity of forest land under climate change.
An integrated mid‐range theory of postpartum family development: a guide for research and practice
Authors: Christie Janice , Poulton Brenda C. , Bunting Brendan P.
Published: November 2007

Title. An integrated mid‐range theory of postpartum family development: a guide for research and practice

Aim. This paper is a report of a study to identify parents’ perceptions of postpartum family experiences.

Background. There is a growing worldwide emphasis on family support. Government policy in the United Kingdom advocates a family‐centred approach in which a core universal postbirth service is offered to all families with additional support for parents of children with complex needs. Health visitors provide family postpartum care without an agreed theory directing or standardizing practice. There is a need to identify parental experiences to define family‐centred care.

Method. A qualitative, exploratory approach was undertaken using a purposive sample of 17 postpartum families. Data were collected in one region of Northern Ireland in 2001–2002. Participants’ experiences and views were accessed during two focus groups with a total of seven participants, and six in‐depth interviews. Thematic analysis was conducted.

Findings. One core theme, ‘thriving and surviving’, and three main themes, ‘baby nurture’, ‘life changes’, ‘coping and adapting resources’, were identified to describe how parents developed during the first 8‐week postpartum. These were influenced by the physical, the psychosocial and the environmental factors. The identified themes were mapped together to form an Integrated Mid‐Range Theory of Postpartum Parent Development.

Conclusion. As parents need to negotiate successfully both present coping and future development during the postpartum period, there is a need for professionals to offer services that are orientated to holistic short‐ and long‐term well‐being. The findings, further to additional research, may be used by health visitors and other professionals to direct universal postpartum care.
Registered Nurses’ perceptions of their work and professional development
Authors: Hallin Karin , Danielson Ella
Published: November 2007

Title.  Registered Nurses’ perceptions of their work and professional development

Aim.  This paper is a report of a study to elucidate Registered Nurses’ perceptions of their work and professional development 6 years after graduation.

Background.  Nursing education and health care has rapidly changed in the last two decades. Education and experience are important components in Registered Nurses’ ability to promote a high quality of care, but a great deal depends on their work circumstances. This study emphasizes Registered Nurses’ view of their work in health care, at a time in their career when they have several years of experience.

Method.  Data were collected in 2003 from in‐depth interviews with 15 Registered Nurses 6 years after their graduation. The interviews were semi‐structured and analysed with interpretive content analysis.

Findings.  The findings revealed two themes and five sub‐themes. The first theme, An appropriate but demanding profession, consisted of two sub‐themes: ‘having found one’s niche’ and ‘growing old in nursing may be difficult’. The second theme, A profession with opportunities and obstacles, consisted of three sub‐themes: ‘being aware of Registered Nurses’ potential’, ‘having knowledge that is seldom made use of’ and ‘attaining professional growth is no matter of course’.

Conclusion.  Keeping Registered Nurses’ satisfied and avoiding their dissatisfaction is crucial for both educators and employers. It is essential that employers give priority to Registered Nurses’ time with patients and to motivate and support them in professional development. Further intervention studies regarding a change of the balance between obstacles and opportunities are needed.
Warrior nurse: duality and complementarity of role in the operational environment
Authors: Griffiths Lauren , Jasper Melanie
Published: November 2007

Title.  Warrior nurse: duality and complementarity of role in the operational environment

Aim.  This paper is a report of a study to explore the nature of military nursing in an environment of war, in particular the union of personal, professional and organizational tenets and to identify the actual or potential effect this had on the nursing role in this unique environment.

Background.  The history of nursing is intrinsically linked with war. There is an irony to this relationship. Active involvement with military activities has provided a vehicle in which nursing has developed, albeit through fostering war, which itself destroys health and contravenes the ethos of nursing. Military nurses, one would assume, are able to reconcile the dichotomy existing between their caring role and being a member of an organization associated with conflict.

Methods.  A grounded theory design was adopted and the data were collected from 1999 to 2002 using a series of in‐depth interviews and focus group with of 24 military nurses.

Findings.  Three categories were identified: ‘It’s Just Different Levels’, ‘That Double Hat’ and ‘It’s Who We Are!’ The first illustrates the reality of conflict. ‘That Double Hat’ outlines the military nurses dual role: those of caring and the military. ‘It’s Who We Are!’ demonstrates the transition from nurse‐to‐warrior. These integrate to create the core category: ‘Caring for War: Transition to Warrior’.

Conclusion.  The symbiotic relationship of carer and warrior arises as a consequence of strategies used by military nurses to embrace their dual role. Further research is needed to explore the essence of the caring role within a conflict zone from military and civilian perspectives.
Experiences and constructions of art: a narrative‐discourse analysis
Authors: STICKLEY T. , HUI A. , MORGAN J. , BERTRAM G.
Published: November 2007

A narrative‐discourse analysis was conducted to study the narratives of mental health service users talking about their engagement with art. The sample was drawn from a group of people who had attended arts workshops organized by a mental health service provider. Eleven people were interviewed and were asked to tell the story of their involvement in art and its significance to their lives. The data were analysed using a discourse analysis approach. Art is constructed as therapeutic within an illness repertoire. Emotions are inseparable from creative expression and identity claims are made in relation tobeing an artist.
Catching life: the contribution of arts initiatives to recovery approaches in mental health
Authors: SPANDLER H. , SECKER J. , KENT L. , HACKING S. , SHENTON J.
Published: November 2007

This paper draws on a qualitative study that was undertaken as part of a national research study to assess the impact of participatory arts provision for people with mental health needs. It explores how arts and mental health projects may facilitate some of the key elements of what has been termed a ‘recovery approach’ in mental health. It is argued that it is precisely these elements – the fostering of hope, creating a sense of meaning and purpose, developing new coping mechanisms and rebuilding identities – which are hard to standardize and measure, yet may be the most profound and significant outcomes of participation in such projects. Therefore, in the context of a growing emphasis on recovery‐orientated mental health services, while not necessarily being appropriate for all service users, arts and mental health initiatives could make an essential contribution to the future of mental health and social care provision.
Experiences in a group of grown‐up children of mentally ill parents
Authors: KNUTSSON‐MEDIN L. , EDLUND B. , RAMKLINT M.
Published: November 2007

Children of mentally ill parents have increased rates of psychopathology and reduced adaptive functioning. However, there are very few studies examining the subjective experiences of those children and their opinions concerning their previous contact with psychiatric services. This study followed up a group of children of former psychiatric inpatients by sending them a questionnaire asking about their experiences. Thirty‐six individuals responded. Answers were analysed qualitatively by using manifest content analysis. Participants reported negative experiences and lack of information and support from psychiatric care. They had wanted more explanations and more support for themselves. Quantitative data are used to establish the significance of the results.
Seeing the psychiatrist: an autoethnographic account
Authors: BURNARD P.
Published: November 2007

Autoethnography is a fairly recent approach to ethnography and one in which the writer becomes the ‘subject’ of the study. It remains an approach under question until more has been done in the field. In this account, I describe attending an interview with a psychiatrist, as a patient. I map out the process I encountered and offer, alongside the map, various critical and reflective comments. I offer a summary of my ‘findings’ and close with a critical evaluation both of the method and of the paper. Findings included: a comfortable and comforting ‘setting up’ of the interview; a sense of moving into the ‘patient role’; a clear indication of how the interview would proceed; and empathic manner on the part of the psychiatrist and a sound process of follow‐through with my general practitioner. In the critique section, I try to answer the question as to whether or not authoethnography is self‐indulgent and the degree to which it can or cannot help others in understanding mental health issues. I remain uncertain about both the method and its value. In the end, it is probably for the reader to answer these questions.
Speciation reversal and biodiversity dynamics with hybridization in changing environments
Authors: SEEHAUSEN OLE , TAKIMOTO GAKU , ROY DENIS , JOKELA JUKKA
Published: November 2007

A considerable fraction of the world's biodiversity is of recent evolutionary origin and has evolved as a by‐product of, and is maintained by, divergent adaptation in heterogeneous environments. Conservationists have paid attention to genetic homogenization caused by human‐induced translocations (e.g. biological invasions and stocking), and to the importance of environmental heterogeneity for the ecological coexistence of species. However, far less attention has been paid to the consequences of loss of environmental heterogeneity to the genetic coexistence of sympatric species. Our review of empirical observations and our theoretical considerations on the causes and consequences of interspecific hybridization suggest that a loss of environmental heterogeneity causes a loss of biodiversity through increased genetic admixture, effectively reversing speciation. Loss of heterogeneity relaxes divergent selection and removes ecological barriers to gene flow between divergently adapted species, promoting interspecific introgressive hybridization. Since heterogeneity of natural environments is rapidly deteriorating in most biomes, the evolutionary ecology of speciation reversal ought to be fully integrated into conservation biology.
Founding events in species invasions: genetic variation, adaptive evolution, and the role of multiple introductions
Authors: DLUGOSCH K. M. , PARKER I. M
Published: November 2007

Invasive species are predicted to suffer from reductions in genetic diversity during founding events, reducing adaptive potential. Integrating evidence from two literature reviews and two case studies, we address the following questions: How much genetic diversity is lost in invasions? Do multiple introductions ameliorate this loss? Is there evidence for loss of diversity in quantitative traits? Do invaders that have experienced strong bottlenecks show adaptive evolution? How do multiple introductions influence adaptation on a landscape scale? We reviewed studies of 80 species of animals, plants, and fungi that quantified nuclear molecular diversity within introduced and source populations. Overall, there were significant losses of both allelic richness and heterozygosity in introduced populations, and large gains in diversity were rare. Evidence for multiple introductions was associated with increased diversity, and allelic variation appeared to increase over long timescales (~100 years), suggesting a role for gene flow in augmenting diversity over the long‐term. We then reviewed the literature on quantitative trait diversity and found that broad‐sense variation rarely declines in introductions, but direct comparisons of additive variance were lacking. Our studies of Hypericum canariense invasions illustrate how populations with diminished diversity may still evolve rapidly. Given the prevalence of genetic bottlenecks in successful invading populations and the potential for adaptive evolution in quantitative traits, we suggest that the disadvantages associated with founding events may have been overstated. However, our work on the successful invader Verbascum thapsus illustrates how multiple introductions may take time to commingle, instead persisting as a ‘mosaic of maladaptation’ where traits are not distributed in a pattern consistent with adaptation. We conclude that management limiting gene flow among introduced populations may reduce adaptive potential but is unlikely to prevent expansion or the evolution of novel invasive behaviour.
Functional biotic homogenization of bird communities in disturbed landscapes
Authors: Devictor Vincent , Julliard Romain , Clavel Joanne , Jiguet Frédéric , Lee Alexandre , Couvet Denis
Published: November 2007

Aim  Worldwide, functional homogenization is now considered to be one of the most prominent forms of biotic impoverishment induced by current global changes. Yet this process has hardly been quantified on a large scale through simple indices, and the connection between landscape disturbance and functional homogenization has hardly been established. Here we test whether changes in land use and landscape fragmentation are associated with functional homogenization of bird communities at a national scale.

Location  France.

Methods  We estimated functional homogenization of a community as the average specialization of the species present in that community. We studied the spatial variation of this community specialization index (CSI) using 1028 replicates from the French Breeding Bird Survey along spatial gradients of landscape fragmentation and recent landscape disturbance, measured independently, and accounting for spatial autocorrelation.

Results  The CSI was very sensitive to both measures of environmental degradation: on average, 23% of the difference in the CSI values between two sample sites was attributed to the difference in fragmentation and the disturbance between sites. This negative correlation between CSI and sources of landscape degradation was consistent over various habitats and biogeographical zones.

Main conclusions  We demonstrate that the functional homogenization of bird communities is strongly positively correlated to landscape disturbance and fragmentation. We suggest that the CSI is particularly effective for measuring functional homogenization on both local and global scales for any sort of organism and with abundance or presence–absence data.
University–industry relationships and open innovation: Towards a research agenda
Authors: Perkmann Markus , Walsh Kathryn
Published: November 2007

Organizations increasingly rely on external sources of innovation via inter‐organizational network relationships. This paper explores the diffusion and characteristics of collaborative relationships between universities and industry, and develops a research agenda informed by an ‘open innovation’ perspective. A framework is proposed, distinguishing university–industry relationships from other mechanisms such as technology transfer or human mobility. On the basis of the existing body of research, the role of practices such as collaborative research, university–industry research centres, contract research and academic consulting is analysed. The evidence suggests that such university–industry relationships are widely practised, whereby differences exist across industries and scientific disciplines. While most existing research focuses on the effects of university–industry links on innovation‐specific variables such as patents or firm innovativeness, the organizational dynamics of these relationships remain under‐researched. A detailed research agenda addresses research needs in two main areas: search and match processes between universities and firms, and the organization and management of collaborative relationships.
Effects of Clamping on the Laser Forming Process
Authors: Birnbaum A. J. , Cheng P. , Yao Y. L.
Published: November 2007

Although considerable effort has gone into characterizing the laser forming process in terms of process parameters and conditions, there has been little emphasis on the effects of the mechanical and thermal constraints introduced by the clamping method utilized for a desired application. This research suggests means for investigating and predicting the resulting geometry of a specimen due to laser operation in close proximity to an array of imposed thermo-mechanical constraints for both the single and multiple scan cases; specifically, the resulting average bending angle as well as bending angle variations throughout the part. This is accomplished by initially only considering these effects on the thermal field. Conclusions are then drawn about the nature of the mechanical effects. These conclusions are validated through numerical simulation as well as physical experimentation. An analytical solution of the thermal problem is also presented for further validation of the temperature field as a constrained edge is approached.
A Tool Path Modification Approach to Cutting Engagement Regulation for the Improvement of Machining Accuracy in 2D Milling With a Straight End Mill
Authors: Uddin M. Sharif , Ibaraki Soichi , Matsubara Atsushi , Nishida Susumu , Kakino Yoshiaki
Published: November 2007

In two-dimensional (2D) free-form contour machining by using a straight (flat) end mill, conventional contour parallel paths offer varying cutting engagement with workpiece, which inevitably causes the variation in cutting loads on the tool, resulting in geometric inaccuracy of the machined workpiece surface. This paper presents an algorithm to generate a new offset tool path, such that the cutting engagement is regulated at a desired level over the finishing path. The key idea of the proposed algorithm is that the semi-finish path, the path prior to the finishing path, is modified such that the workpiece surface generated by the semi-finish path gives the desired engagement angle over the finishing path. The expectation with the proposed algorithm is that by regulating the cutting engagement angle along the tool path trajectory, the cutting force can be controlled at any desirable value, which will potentially reduce variation of tool deflection, thus improving geometric accuracy of machined workpiece. In this study, two case studies for 2D contiguous end milling operations with a straight end mill are shown to demonstrate the capability of the proposed algorithm for tool path modification to regulate the cutting engagement. Machining results obtained in both case studies reveal far reduced variation of cutting force, and thus, the improved geometric accuracy of the machined workpiece contour.
Precision Motion Control Methodology for Complex Contours
Authors: Zhang Haojiong , Landers Robert G.
Published: November 2007

A general precision motion control methodology for complex contours is proposed in this paper. Each motion servomechanism dynamic model is divided into a linear portion and a portion containing nonlinear friction, unmodeled dynamics, and unknown disturbances. A full state feedback controller, based on a state space error system model, is developed to track general reference trajectories. The lumped static, Coulomb, and Stribeck friction effects are described using the Tustin friction model. Unmodeled dynamics and unknown disturbances are estimated using a Kalman filter that employs a first-order stochastic model. The nonlinear friction, unmodeled dynamics, and unknown disturbances are directly canceled by the controller. In the proposed motion control methodology, complex contours (i.e., contours whose radii of curvature constantly change along the contour) do not need to be decomposed into line segments and arcs and the reference signals do not need to be prefiltered. Also, the controller structure does not need to be adjusted to track different types of contours. Experiments are conducted on a two-axis laboratory grade machine tool for elliptical, limacon, and free-form contours. The results demonstrate the excellent tracking performance of the proposed motion control methodology. They also demonstrate that the performance is independent of the contours’ complexity.
Dynamique du carbone et de l'azote chez le Carex rostrata, l’Eriophorum vaginatum et le Calluna vulgaris dans une tourbière à sphaignes des monts du Forez (France)
Authors: Francez André-Jean
Published: November 2007

Seasonal fluctuations in the biomass, necromass, and litter decay of Carex rostrata, Eriophorum vaginatum, and Calluna vulgaris were studied in the mire complex of Côte-de-Braveix, at 1350 m of altitude in the Forez Mountains of the eastern part of the Massif central (France). The primary production of these three dominant species of the main development stages of the studied peatland were respectively 456, 353, and 531 g ∙ m−2 ∙ a−1; the corresponding N fluxes were 4.5 g ∙ m−2 ∙ a−1 for the first two species and 5.2 g ∙ m−2 ∙ a−1 for the latter. The subterranean parts (rhizomes and roots) represented 66, 73 and 46% of the C production and 44, 47 and 37% of the N production, respectively. The biomass and N turnover rates were the highest in the E. vaginatum community (1.3 and 1.6) and the lowest in C. vulgaris (0.8 and 0.9); they were 1.1 and 1.2 in the C. rostrata community. The first year decomposition rate was equal to 0.30, 0.21 and 0.16 in the C. rostrata, E. vaginatum, and C. vulgaris litters. The production/accumulation ratio decreased from the fen to the bog species : 1.4 (C. rostrata), 1.3 (E. vaginatum), and 1.2 (C. vulgaris). The C and N balances are discussed from the viewpoint of ecological succession and peatland ecosystem development. Key words: fen, bog, primary production, decomposition, peat, succession.
Impact of rainbow smelt (Osmerus mordax) invasion on walleye (Sander vitreus) recruitment in Wisconsin lakes
Authors: Mercado-Silva Norman , Sass Greg G , Roth Brian M , Gilbert Stephen , Zanden M Jake Vander
Published: November 2007

Rainbow smelt (Osmerus mordax) are invaders of inland lakes in the Laurentian Great Lakes region of North America and have negatively affected native fish populations. Walleye (Sander vitreus) comprise an important fishery throughout the Great Lakes region and could be affected by rainbow smelt invasions. We test for declines of young-of-the-year walleye (YOY-W) density in 12 of the 26 known rainbow smelt invaded lakes in Wisconsin. Invaded lakes showed significantly lower YOY-W densities than uninvaded lakes during the period 1985–2004. In 94% (17/18) of years, YOY-W densities from invaded lakes were lower than those from uninvaded lakes. Declines (~70%) in YOY-W densities were observed in three lakes with data from before and after rainbow smelt invasion. For 10 invaded lakes with more than two YOY-W density estimates between 1985 and 2004, YOY-W densities averaged 13% below expected densities. Our results demonstrate the potential impacts of rainbow smelt invasion on walleye tribal, commercial, and recreational fisheries and highlight the importance of preventing their further spread.
Relationship between smolt gill Na+, K+ ATPase activity and migration timing to avian predation risk of steelhead trout (Oncorhynchus mykiss) in a large estuary
Authors: Kennedy Benjamen M , Gale William L , Ostrand Kenneth G
Published: November 2007

We examined avian predation risk of juvenile steelhead trout (Oncorhynchus mykiss) migrating through the Columbia River Estuary in relation to their osmoregulatory physiology, body length, rearing conditions (hatchery or wild), migration timing, and migration year. From 2003 to 2006, mean gill Na+, K+ ATPase activity of migrating wild steelhead was greater than hatchery steelhead. Hatchery steelhead were always longer than wild steelhead. Wild steelhead never had higher plasma [Na+] or osmolality levels than hatchery fish after seawater challenge trials conducted in 2004, 2005, and 2006. More passive integrated transponder (PIT) tags from hatchery fish (19%; 126 of 678 fish) were detected on East Sand Island among bird nesting colonies than PIT tags of wild fish (14%; 70 of 509 fish), presumably consumed by birds. As gill Na+, K+ ATPase activity and migration date within a year increased, the probability of an individual fish being eaten by an avian predator decreased. Length, rear type, and year were not related to predation risk. These results show that physiology and migration timing of juvenile steelhead play an important role in a migrants risk to avian predation within an estuary.
Modelling of wood density and fibre dimensions in mature Norway spruce
Authors: Molteberg Dag , Høibø Olav
Published: November 2007

Basic density (BD), fibre length (FL), fibre width (FW), and fibre wall thickness (FWT) were investigated in 46 Norway spruce ( Picea abies (L.) Karst.) trees from five different stands in eastern Norway. From each tree, wood samples were collected in different radial and longitudinal positions. Random coefficient mixed models were used to investigate variation within as well as among trees, both within and among stands. The R2 with random effects included, describing the best possible (individual) fit of the observed data to the models, were 0.90 for BD, 0.99 for FL, 0.88 for FW, and 0.91 for FWT. With only fixed effects, the best model explained 56% of the total variation for BD, 94.5% for FL, 61% for FW, and 63% for FWT. A common model for all trees, without tree and site information, predicted FL well but BD, FW, and FWT poorly. Adding site index, breast height diameter, and tree height to the models reduced the residual variance considerably for FW, FWT, and particularly BD, whereas only a minor improvement was gained for FL. The latter type of models might be easier to use for industrial purposes. Although information about ring width gave further improvements, ring width measurements are time consuming and difficult to perform in the forest and in industrial environments.
Clonal variation in shoot respiration and tree growth of Eucalyptus hybrids
Authors: Callister Andrew N. , Ades Peter K. , Arndt Stefan K. , Adams Mark A.
Published: November 2007

Respiration rate and efficiency in growing tissues are major determinants of plant growth. We measured apical shoot respiration and tree growth in 3-year-old clones of Eucalyptus camaldulensis Dehnhardt × Eucalyptus grandis W. Hill ex Maid. and Eucalyptus camaldulensis × Eucalyptus globulus Labill. Respiration was measured by isothermal calorimetry and the oxidation state of newly formed biomass was determined by elemental analysis. We found that the enthalpy change due to conversion of carbon substrate to biomass was too small for determining specific growth rate by an enthalpy balance model of respiration and growth. Negative phenotypic correlations were significant between respiration rate and basal area, height, volume, and volume growth. Genetic correlations between respiration rate and tree size or growth were mostly significant and estimates ranged from –0.55 to –1.02. Repeatability of the clone means was around 0.80 for respiration rate, 0.71–0.91 for summer growth, and in excess of 0.80 for tree size traits. The intraclass correlation for clones (within families) was 0.33 for rate of CO2 evolution and 0.45 for rate of metabolic heat evolution. Our results suggest considerable potential for altering respiration rate in breeding populations by selection, although the mechanisms linking respiration with growth require further investigation.
Aspen competition affects light and white spruce growth across several boreal sites in western Canada
Authors: Filipescu Cosmin N. , Comeau Philip G.
Published: November 2007

The effectiveness of competition indices for predicting light transmittance and white spruce ( Picea glauca (Moench) Voss) growth were examined across trembling aspen ( Populus tremuloides Michx.) density gradients using sites from a long-term study of mixedwood growth and development in Alberta and Saskatchewan. Competition indices based on density (number of trees, basal area, and spacing factor), distance-dependent and -independent size ratio (Hegyi’s and Lorimer’s), and crown characteristics (crown volume, surface area, and cross-sectional area) were tested. Transmittance was effectively predicted by crown competition indices followed closely by aspen basal area and size ratio indices. Models of spruce growth indicated better results for stem volume compared with diameter or height. Competition alone accounted for less than 60% of stem growth variation, with basal area and transmittance providing some of the best models. The predictive ability of spruce growth was increased up to 93% by adding initial size as a second explanatory variable. In this respect, initial diameter was superior to initial height, crown volume, and surface area. Relationships between competition, transmittance, and spruce growth were found to differ significantly between geographical locations. These results suggest the need for local development of models relating tree growth to competition.
Differential responsiveness in stem height and diameter growth of twoFicustree species in the Three Gorges reservoir region of China as affected by branch removal
Authors: Zhang Xiaoping , Zeng Bo , Zhong Zhangcheng
Published: November 2007

In the Three Gorges reservoir region of China, Ficus microcarpa L. and Ficus virens Ait. var. sublanceolata (Miq.) Corner (Moraceae) are widely used in greening and ecological restoration following construction, including roads, railways, towns, etc. Branch cuttings are used for cultivating saplings of these trees. We conducted a 4 year experiment that included four branch-removal intensities to evaluate the influence of branch removal on stem height and diameter growth of these Ficus spp. It was found that branch removal did not affect the stem height growth of either F. microcarpa or F. virens, but decreased the growth of their stem basal diameters. The reduction in growth of stem basal diameter was intensified with branch removal. As expected, branch removal decreased the tapering of whole tree stems, but this effect was mainly due to the alteration of the shape of the bare stem part, and the shape of the stem part within the intact upper crown was not affected by the treatment. The data clearly showed that stem height growth was less sensitive than stem diameter growth to branch removal, and that the response of stem diameter growth to branch removal differed between bare and intact stem parts.
How do forest harvesting methods compare with wildfire? A case study of soil chemistry and tree nutrition in the boreal forest
Authors: Thiffault Evelyne , Bélanger Nicolas , Paré David , Munson Alison D.
Published: November 2007

An important tenet of the natural disturbance paradigm as a basis for sustainable forest management is that impacts of interventions fall within the range of natural variation observed for the disturbance in question. We evaluated differences in soil nutrients, soil acid–base status, and tree nutrition between two harvesting methods (whole-tree (WTH) and stem-only (SOH)) and wildfire, 15–20 years after disturbance, to assess whether these harvesting methods have biogeochemical impacts that are within the natural range of variation caused by wildfires in boreal coniferous stands of Haute-Mauricie (Quebec). Both SOH and WTH created conditions of forest floor effective cation-exchange capacity, exchangeable Ca and K concentrations, base saturation, Ca:Al molar ratio, and organic C concentrations that were lower than the range of values for wildfires. We hypothesize that the immediate deposition of soluble base cations and the incorporation of recalcitrant organic matter that characterize wildfires generate biogeochemical conditions that are not emulated by either harvesting method. The improved soil nutritional environment after wildfire compared with SOH and WTH was reflected in jack pine ( Pinus banksiana Lamb.) foliar nutrient composition but not in black spruce ( Picea mariana (Mill.) BSP) foliage. The results raise uncertainties about the long-term base nutrient availability of the harvested sites on Boreal Shield soils.
Validation and refinement of allometric equations for roots of northern hardwoods
Authors: Vadeboncoeur Matthew A. , Hamburg Steven P. , Yanai Ruth D.
Published: November 2007

The allometric equations developed by Whittaker et al. (1974. Ecol. Monogr. 44: 233–252) at the Hubbard Brook Experimental Forest have been used to estimate biomass and productivity in northern hardwood forest systems for over three decades. Few other species-specific allometric estimates of belowground biomass are available because of the difficulty in collecting the data, and such equations are rarely validated. Using previously unpublished data from Whittaker’s sampling effort, we extended the equations to predict the root crown and lateral root components for the three dominant species of the northern hardwood forest: American beech ( Fagus grandifolia Ehrh.), yellow birch ( Betula alleghaniensis Britt), and sugar maple ( Acer saccharum Marsh.). We also refined the allometric models by eliminating the use of very small trees for which the original data were unreliable. We validated these new models of the relationship of tree diameter to the mass of root crowns and lateral roots using root mass data collected from 12 northern hardwood stands of varying age in central New Hampshire. These models provide accurate estimates of lateral roots (<10 cm diameter) in northern hardwood stands >20 years old (mean error 24%–32%). For the younger stands that we studied, allometric equations substantially underestimated observed root biomass (mean error >60%), presumably due to remnant mature root systems from harvested trees supporting young root-sprouted trees.
AC CONDUCTIVITY OF GRAPHENE: FROM TIGHT-BINDING MODEL TO 2 + 1-DIMENSIONAL QUANTUM ELECTRODYNAMICS
Authors: GUSYNIN V. P. , SHARAPOV S. G. , CARBOTTE J. P.
Published: November 2007

We consider the relationship between the tight-binding Hamiltonian of the two-dimensional honeycomb lattice of carbon atoms with nearest neighbor hopping only and the 2 + 1 dimensional Hamiltonian of quantum electrodynamics, which follows in the continuum limit. We pay particular attention to the symmetries of the free Dirac fermions including spatial inversion, time reversal, charge conjugation and chirality. We illustrate the power of such a mapping by considering the effect of the possible symmetry breaking, which corresponds to the creation of a finite Dirac mass, on various optical properties. In particular, we consider the diagonal AC conductivity with emphasis on how the finite Dirac mass might manifest itself in experiment. The optical sum rules for the diagonal and Hall conductivities are discussed.
NUMERICAL ANALYSIS OF THE PSI SOLUTION OF ADVECTION–DIFFUSION PROBLEMS THROUGH A PETROV–GALERKIN FORMULATION
Authors: CHACÓN REBOLLO TOMÁS , GÓMEZ MÁRMOL MACARENA , NARBONA REINA GLADYS
Published: November 2007

In this paper we introduce an analysis technique for the solution of the steady advection–diffusion equation by the PSI (Positive Streamwise Implicit) method. We formulate this approximation as a nonlinear finite element Petrov–Galerkin scheme, and use tools of functional analysis to perform a convergence, error and maximum principle analysis. We prove that the scheme is first-order accurate in H1 norm, and well-balanced up to second order for convection-dominated flows. We give some numerical evidence that the scheme is only first-order accurate in L2 norm. Our analysis also holds for other nonlinear Fluctuation Splitting schemes that can be built from first-order monotone schemes by the Abgrall and Mezine's technique.
Molecular Mechanisms of Liver Carcinogenesis in the Mdr2-Knockout Mice
Authors: Katzenellenbogen Mark , Mizrahi Lina , Pappo Orit , Klopstock Naama , Olam Devorah , Jacob-Hirsch Jasmine , Amariglio Ninette , Rechavi Gideon , Domany Eytan , Galun Eithan , Goldenberg Daniel
Published: November 2007

Mouse models of hepatocellular carcinoma (HCC) simulate specific subgroups of human HCC. We investigated hepatocarcinogenesis in Mdr2-knockout (Mdr2-KO) mice, a model of inflammation-associated HCC, using gene expression profiling and immunohistochemical analyses. Gene expression profiling showed that although Mdr2-KO mice differ from other published murine HCC models, they share several important deregulated pathways and many coordinately differentially expressed genes with human HCC data sets. Analysis of genome positions of differentially expressed genes in liver tumors revealed a prolonged region of down-regulated genes on murine chromosome 8 in three of the six analyzed tumor samples. This region is syntenic to human chromosomal regions that are frequently deleted in human HCC and harbor multiple tumor suppressor genes. Real-time reverse transcription-PCR analysis of 16 tumor samples confirmed down-regulation of several tumor suppressors in most tumors. We show that in the aged Mdr2-KO mice, cyclin D1 nuclear level is increased in dysplastic hepatocytes that do not form nodules; however, it is decreased in most dysplastic nodules and in liver tumors. We found that this decrease is mostly at the protein, rather than the mRNA, level. These findings raise the question on the role of cyclin D1 at early stages of hepatocarcinogenesis in the Mdr2-KO HCC model. Furthermore, we show that most liver tumors in Mdr2-KO mice were characterized by the absence of β-catenin activation. In conclusion, the Mdr2-KO mouse may serve as a model for β-catenin–negative subgroup of human HCCs characterized by low nuclear cyclin D1 levels in tumor cells and by down-regulation of multiple tumor suppressor genes. (Mol Cancer Res 2007;5(11):1159–70)
Sex Determination in Birds: HINTs from the W Sex Chromosome?
Authors: Smith C.A.
Published: November 2007

Sex in birds is controlled genetically (ZZ male: ZW female), but the genetic mechanism remains unclear. While some evidence points to the involvement of Z sex chromosome dosage, other data favour a dominant female-determining gene carried on the W sex chromosome. An intriguing candidate gene located on the chicken W chromosome is HINTW, which encodes an aberrant form of a hydrolase enzyme. In chicken embryos, HINTW is strongly expressed in the gonads and other tissues of ZW (female) embryos. In vitro biochemical data show that HINTW can interfere with the action of a Z-linked orthologue, HINTZ, which is a bona fide hydrolase enzyme. HINTW is conserved among carinate (flying) birds, and recent molecular analysis indicates that it has undergone positive selection over evolution. However, a differentiated HINTW gene appears to be absent in the flightless ratites. This review examines the evidence for and against a role for HINTW in avian sex determination.
Anterior Displacement of the Inferior Vena Cava By Hepatic Masses
Authors: Sprayregen Seymour
Published: November 2007

Two cases are reported in which hepatomas produced anterior displacement of the inferior vena cava, and because of this displacement were originally considered to represent retroperitoneal masses. The hepatoma in one case involved the caudate lobe and in the other the right lobe of the liver, with neither case having evidence of retroperitoneal disease.

No previous inferior vena cavagram has been published which showed anterior displacement of the vena cava by a hepatic mass. Hepatic masses must be considered in the differential diagnosis when the upper portion of the inferior vena cava is displaced anteriorly. The anatomic factors which allow intrahe patic masses to displace the vena cava anteriorly are discussed.
The Vascular Lesions of Neurofibromatosis
Authors: Salyer William R. , Salyer Diane C.
Published: November 2007

Peculiar arterial lesions were found in seven of 18 cases of neurofi bromatosis. As previously described, these were of four types: pure intimal, advanced intimal, intimal aneurysmal, and nodular. Many lesions had features of more than one of the pure types. Other characteristics of the lesions suggested that they are of Schwann cell origin. It is proposed that the pathogenesis of all of the types of arterial lesions is the same—the proliferation of Schwann cells within arteries with secondary degenerative changes, e.g., fibrosis, resulting in lesions with very different appearances.
Vascular Insufficiency and Osteomyelitis of the Lower Extremity
Authors: Kerstein Morris D.
Published: November 2007

Osteomyelitis secondary to peripheral vascular insufficiency was evaluated in forty-six males. A control group of sixteen did not receive antibiotics; the remainder received Cephalothin pre- and post-operatively. An equal number of patients in both groups had diabetes mellitus. Based on x-ray and clinical findings, all patients underwent local amputation. Staphylococcus aureus was the most common organism recovered. Thirty-seven percent of the non-antibiotic treated group required further revision to a higher level of amputation.

The most frequent cause of amputation of the lower extremity is atherosclerosis, complicated by diabetes mellitus and infection.2 Progression of the primary disease process often results in ulceration, sepsis, gangrene and osteomyelitis. The responsible surgeon must not "whittle" nor must he be too aggressive. Evaluating the rehabilitation potential of each individual, and being aware of the disability incurred by amuputation, "selective conservatism" is the key. This study demonstrates the selected salvage of the lower extremity by limited amputation and long term antibiotic therapy.
Deep Vein Thrombosis Treated With Streptokinase or Heparin
Authors: Common Herbert H. , Seaman Arthur J. , Rösch Josef , Porter John M. , Dotter Charles T.
Published: November 2007

Twenty-seven patients with deep vein thrombosis whose primary therapy was randomized between streptokinase and heparin were reevaluated clinically and by ascending venography after a mean period of 7 months. Normal venograms were found in 6 (40%) of the streptokinase-treated patients and in 1 patient (8%) who had heparin therapy. Segmental valve preservation was found in 1 patient from each group. All patients with complete or partial valve preservation became asymptomatic. Vein re canalization without preservation of valves occurred in 18 patients: 8 (54%) of those on streptokinase, and 10 (83%) of those on heparin. At the time of follow-up, 11 of these 18 patients, including 8 who had had prior thrombosis, reported peripheral edema; the postphlebitic syndrome devel oped in 1. Factors favoring a good outcome of acute venous thrombosis were (1) no prior thrombotic disease, (2) localized thrombosis, and (3) prompt streptokinase therapy.