bluuebunny/crossref_metadata_2025_split huggingface dataset:
Different methods, different results: temporal trends in the study of nested subset patterns in parasite communities
Authors: TIMI J. T. , POULIN R. 
Published: September 2007

SUMMARYThe search for nested subset patterns has become a powerful tool for understanding the processes shaping parasite communities. Here, we re-examine the results of past studies on nestedness in parasite communities, to assess how sensitive they are to the analytical method used. Using the metricNand the null model RANDOM1, the first method available to study nested patterns, early studies concluded that nestedness was infrequent in parasite communities. In contrast later studies, using instead the metricTand the nestedness temperature calculator (NTC), found that nested subset patterns were very common in parasite communities. Recently, a new algorithm, the binary matrix nestedness temperature calculator (BINMATNEST), has been proposed to quantify nestedness. Using data on 31 helminth communities of fish hosts, we show that applying the NTC yields consistently more significant nested patterns than whenNand RANDOM1 are used on the same data. The use of BINMATNEST produced results that depend on the choice of the null model. To provide a benchmark, a straightforward comparison between the observed frequencies of co-occurrences of species with those expected from their prevalence under random assembly was also made for each community. This test indicates that random structure occurs in practically all communities, even those where one of the nestedness analyses found a significant pattern. We demonstrate that the probability of finding a nested pattern in a parasite community depends entirely on the metric and null model chosen for analysis.
Mass balance and dynamics of a valley glacier measured by high-resolution LiDAR
Authors: Rees W. G. , Arnold N. S. 
Published: September 2007

ABSTRACTThe changing surface geometry of the glacier Midre Lovénbreen on Svalbard was investigated using LiDAR data acquired on 9 August 2003 and again on 5 July 2005. The data were processed to generate Digital Elevation Models (DEMs) of unprecedentedly high spatial resolution (2 m) and accuracy (better than 0.15 m). Comparison of the two DEMs allowed the mass balance of the glacier to be determined as more negative than −0.62 m yr−1 water equivalent, about twice as negative as the value estimated from in situ measurements. Comparison of the DEMs also showed that the area of the glacier decreased by around 0.3%, and the position of its margin retreated by around 14 m, from 2003 to 2005. It was also possible to track the motion of fine-scale features in the surface geometry such as meltwater channels, and hence to determine the glacier's surface velocity, in some areas. Typical average speeds were around 1–2 cm per day.
Derivation and assessment of vegetation maps for reindeer pasture analysis in Arctic European Russia
Authors: Rees W.G. , Danks F.S. 
Published: September 2007

ABSTRACTThroughout northern Eurasia, the presence of reindeer is a complicating factor in the consideration of interactions between vegetation and climate. The ability to interpret future changes in these interactions will depend on access to maps of sufficient detail to represent aspects of vegetation distribution relevant to reindeer grazing, amongst which we particularly identify lichens and shrubs. Such maps, if they are to have circumpolar coverage, can only feasibly be produced on a routine basis using satellite imagery having wide swaths but comparatively coarse resolution. This paper presents qualitative and quantitative comparisons between three such maps, and two more detailed vegetation maps compiled from fieldwork and from recent field-trained satellite image analysis, all for a study area in the Nenets Autonomous Okrug, Russia. It is shown that, despite its high degree of generalisation, the Circumpolar Arctic Vegetation Map provides the best representation of the vegetation in the study area amongst the three circumpolar land-cover maps that were examined, but that none of the three is entirely satisfactory. While the adequate representation of shrubs and lichens currently continues to depend on the analysis of field data or high-resolution satellite imagery which is unsuitable for circumpolar mapping, it is suggested that the prospects for satellite-based circumpolar vegetation mapping capable of including these components is promising.
Visualising cryospheric images in a virtual environment: present challenges and future implications
Authors: Ballagh Lisa M. , Parsons Mark A. , Swick Ross 
Published: September 2007

ABSTRACTThe United States National Snow and Ice Data Center (NSIDC) initiated an outreach project to enhance the visibility of and interest in cryospheric images. Methods were utilised to convert cryospheric data into a projection and image format compatible with Google Earth™. The word ‘image’ should be emphasised since raster data in a native polar projection and format cannot be overlaid on the Earth without prior data conversions. The project focused on reaching out to a diverse audience by integrating images from key components of the cryosphere into a single compressed Keyhole Markup Language (KMZ) file. As a result, users can visualise glacier photographs, permafrost type and extent, sea ice concentration and extent, and snow extent superimposed on the Earth. Those interested in browsing the NSIDC collection of over 3,000 glacier photographs have the option of zooming into Alaska for a majority of the images and accessing both the photograph and the associated metadata. For a current perspective of global snow and ice coverage, one could look at satellite imagery derived from passive microwave Special Sensor Microwave/Imager (SSM/I) data. Another option is to select the permafrost layer and observe the various types and extent of permafrost. This paper explores the project by describing the data, methodologies and results and concludes with future implications on how to improve the processing and functionality of polar data in Google Earth.
Improving the prediction of wildfire potential in boreal Alaska with satellite imaging radar
Authors: Bourgeau-Chavez Laura L. , Garwood Gordon , Riordan Kevin , Cella Brad , Alden Sharon , Kwart Mary , Murphy Karen 
Published: September 2007

ABSTRACTAlaska currently relies on the Canadian Fire Weather Index (FWI) System for the assessment of the potential for wildfire and although it provides invaluable information it is designed as a single system that does not account for the varied fuel types and drying conditions (day length, permafrost, decomposition rate, and soil type) that occur across the North American boreal forest. The FWI System is completely weather-based using noontime measurements of precipitation, relative humidity, temperature and wind speed. The most common problem observed with the FWI system is in the initialisation and need for calibration of one of the moisture codes that make up the FWI system, the Drought Code (DC), which is representative of the deeper organic soil layers and has a 53 day lag period. SAR data represent an innovative tool to improve the current weather-based fire danger system of interior Alaska by initialising the spring values of DC, calibrating the codes throughout the season and providing additional point-source data. Using radar backscatter values from several recently burned boreal forests, an algorithm was developed that related backscatter to DC. The authors then demonstrated the application and validation of this algorithm at independent test sites with good correlation toin situsoil moisture and rainfall variations.
The influence of specific chronic somatic conditions on the care for co-morbid depression in general practice
Authors: Nuyen J. , Spreeuwenberg P. M. , Van Dijk L. , den Bos G. A. M. Van , Groenewegen P. P. , Schellevis F. G. 
Published: September 2007

BackgroundLimited information exists on the relationship between specific chronic somatic conditions and care for co-morbid depression in primary care settings. Therefore, the present prospective, general practice-based study examined this relationship.MethodLongitudinal data on morbidity, prescribing and referrals concerning 991 patients newly diagnosed with depression by their general practitioner (GP) were analysed. The influence of a broad range of 13 specific chronic somatic conditions on the initiation of any depression care, as well as the prescription of continuous antidepressant therapy for 180 days, was examined. Multilevel logistic regression analysis was used to control for history of depression, psychiatric co-morbidity, sociodemographics and interpractice variation.ResultsMultilevel analysis showed that patients with pre-existing ischaemic heart disease (72.1%) or cardiac arrhythmia (59.3%) were significantly less likely to have any depression care being initiated by their GP than patients without chronic somatic morbidity (88.0%). No other specific condition had a significant influence on GP initiation of any care for depression. Among the patients being prescribed antidepressant treatment by their GP, none of the conditions was significantly associated with being prescribed continuous treatment for 180 days.ConclusionsOur study indicates that patients with ischaemic heart disease or cardiac arrhythmia have a lower likelihood of GP initiation of any care for depression after being newly diagnosed with depression by their GP. This finding points to the importance of developing interventions aimed at supporting GPs in the adequate management of co-morbid depression in heart disease patients to reduce the negative effects of this co-morbidity.
Parental punitive discipline, negative life events and gene–environment interplay in the development of externalizing behavior
Authors: Button T. M. M. , Lau J. Y. F. , Maughan B. , Eley T. C. 
Published: September 2007

BackgroundTo investigate the extent to which three putative ‘environmental’ risk factors, maternal punitive discipline (MPD), paternal punitive discipline (PPD) and negative life events (NLEs), share genetic influences with, and moderate the heritability of, externalizing behavior.MethodThe sample consisted of 2647 participants, aged 12–19 years, from the G1219 and G1219Twins longitudinal studies. Externalizing behavior was measured using the Youth Self-Report, MPD, PPD and exposure to NLEs were assessed using the Negative Sanctions Scale and the Life Event Scale for Adolescents respectively.ResultGenetic influences overlapped for externalizing behavior and each ‘environmental’ risk, indicating gene–environment correlation. When controlling for the gene–environment correlation, genetic variance decreased, and both shared and non-shared environmental influences increased, as a function of MPD. Genetic variance increased as a function of PPD, and for NLEs the only interaction effect was on the level of non-shared environment influence unique to externalizing behavior.ConclusionThe magnitude of the influence of genetic risk on externalizing behavior is contextually dependent, even after controlling for gene–environment correlation.
Collaborative care for depression in UK primary care: a randomized controlled trial
Authors: Richards D. A. , Lovell K. , Gilbody S. , Gask L. , Torgerson D. , Barkham M. , Bland M. , Bower P. , Lankshear A. J. , Simpson A. , Fletcher J. , Escott D. , Hennessy S. , Richardson R. 
Published: September 2007

BackgroundCollaborative care is an effective intervention for depression which includes both organizational and patient-level intervention components. The effect in the UK is unknown, as is whether cluster- or patient-randomization would be the most appropriate design for a Phase III clinical trial.MethodWe undertook a Phase II patient-level randomized controlled trial in primary care, nested within a cluster-randomized trial. Depressed participants were randomized to ‘collaborative care’ – case manager-coordinated medication support and brief psychological treatment, enhanced specialist and GP communication – or a usual care control. The primary outcome was symptoms of depression (PHQ-9).ResultsWe recruited 114 participants, 41 to the intervention group, 38 to the patient randomized control group and 35 to the cluster-randomized control group. For the intervention compared to the cluster control the PHQ-9 effect size was 0.63 (95% CI 0.18–1.07). There was evidence of substantial contamination between intervention and patient-randomized control participants with less difference between the intervention group and patient-randomized control group (−2.99, 95% CI −7.56 to 1.58, p=0.186) than between the intervention and cluster-randomized control group (−4.64, 95% CI −7.93 to −1.35, p=0.008). The intra-class correlation coefficient for our primary outcome was 0.06 (95% CI 0.00–0.32).ConclusionsCollaborative care is a potentially powerful organizational intervention for improving depression treatment in UK primary care, the effect of which is probably partly mediated through the organizational aspects of the intervention. A large Phase III cluster-randomized trial is required to provide the most methodologically accurate test of these initial encouraging findings.
Co-morbidity and disorder-related distress and impairment in purging disorder
Authors: Keel P. K. , Wolfe B. E. , Gravener J. A. , Jimerson D. C. 
Published: September 2007

BackgroundRecent studies suggest that purging disorder (PD) may be a common eating disorder that is associated with clinically significant levels of distress and high levels of psychiatric co-morbidity. However, no study has established evidence of disorder-related impairment or whether distress is specifically related to PD rather than to co-morbid disorders.MethodThree groups of normal-weight women [non-eating disorder controls (n=38), with PD (n=24), and with bulimia nervosa (BN)-purging subtype (n=57)] completed structured clinical interviews and self-report assessments.ResultsBoth PD and BN were associated with significant co-morbidity and elevations on indicators of distress and impairment compared to controls. Compared to BN, PD was associated with lower rates of current and lifetime mood disorders but higher rates of current anxiety disorders. Elevated distress and impairment were maintained in PD and BN after controlling for Axis I and Axis II disorders.ConclusionsPD is associated with elevated distress and impairment and should be considered for inclusion as a provisional disorder in nosological schemes such as the Diagnostic and Statistical Manual to facilitate much-needed research on this clinically significant syndrome.
Effects of psychotherapy on regional cerebral blood flow during trauma imagery in patients with post-traumatic stress disorder: a randomized clinical trial
Authors: Lindauer R. J. L. , Booij J. , Habraken J. B. A. , van Meijel E. P. M. , Uylings H. B. M. , Olff M. , Carlier I. V. E. , den Heeten G. J. , van Eck-Smit B. L. F. , Gersons B. P. R. 
Published: September 2007

BackgroundFunctional brain-imaging studies in post-traumatic stress disorder (PTSD) have suggested functional alterations in temporal and prefrontal cortical regions. Effects of psychotherapy on these brain regions have not yet been examined.MethodTwenty civilian PTSD out-patients and 15 traumatized control subjects were assessed at baseline using psychometric ratings. Cerebral blood flow was measured using trauma script-driven imagery during99mtechnetium hexamethyl-propylene-amine-oxime single-photon emission computed tomography scanning. All 20 out-patients were randomly assigned to treatment or wait-list conditions. Treatment was brief eclectic psychotherapy (BEP) in 16 weekly individual sessions.ResultsAt baseline, greater activation was found in the right insula and right superior/middle frontal gyrus in the PTSD group than in the control group. PTSD patients treated with BEP significantly improved on all PTSD symptom clusters compared to those on the waiting list. After effective psychotherapy, lower activation was measured in the right middle frontal gyrus, compared to the PTSD patients on the waiting list. Treatment effects on PTSD symptoms correlated positively with activation in the left superior temporal gyrus, and superior/middle frontal gyrus.ConclusionsBEP induced clinical recovery in PTSD patients, and appeared to modulate the functioning of specific PTSD-related sites in the prefrontal cortical regions.
MRI-based morphometry in children with multiple complex developmental disorder, a phenotypically defined subtype of pervasive developmental disorder not otherwise specified
Authors: Lahuis B. E. , Durston S. , Nederveen H. , Zeegers M. , Palmen S. J. M. C. , Van Engeland H. 
Published: September 2007

BackgroundThe DSM-IV-R classification Pervasive Developmental Disorder – Not otherwise Specified (PDD-NOS) is based on the symptoms for autism and includes a wide variety of phenotypes that do not meet full criteria for autism. As such, PDD-NOS is a broad and poorly defined residual category of the autism spectrum disorders. In order to address the heterogeneity in this residual category it may be helpful to define clinical and neurobiological subtypes. Multiple complex developmental disorder (MCDD) may constitute such a subtype. In order to study the neurobiological specificity of MCDD in comparison with other autism spectrum disorders, we investigated brain morphology in children (age 7–15 years) with MCDD compared to children with autism and typically developing controls.MethodStructural MRI measures were compared between 22 high-functioning subjects with MCDD and 21 high-functioning subjects with autism, and 21 matched controls.ResultsSubjects with MCDD showed an enlarged cerebellum and a trend towards larger grey-matter volume compared to control subjects. Compared to subjects with autism, subjects with MCDD had smaller intracranial volume.ConclusionsWe report a pattern of volumetric changes in the brains of subjects with MCDD, similar to that seen in autism. However, no enlargement in head size was found. This suggests that although some of the neurobiological changes associated with MCDD overlap with those in autism, others do not. These neurobiological changes may reflect differences in the developmental trajectories associated with these two subtypes of autism spectrum disorders.
On the ergodicity of Weyl sum cocycles
Authors: GRESCHONIG GERNOT , NERURKAR MAHESH , VOLNÝ DALIBOR 
Published: September 2007

AbstractWe present the quadratic Weyl sums$\sum _{k=0}^{n-1} e^{2\pi i(k^2\theta +2kx)}$withθ,x∈[0,1) as cocycles over a measure-preserving transformation on the two-dimensional torus. We show then that these cocycles are not coboundaries for every irrationalθ∈[0,1), and that for a denseGδset ofθ∈[0,1) the corresponding skew product is ergodic. For each of thoseθ, there exists a denseGδset of full measure ofx∈[0,1) for which the sequence$\sum _{k=0}^{n-1} e^{2\pi i(k^2\theta +2kx)}$,n=1,2,… , is dense in$\mathbb {C}$.
KMS states and branched points
Authors: IZUMI MASAKI , KAJIWARA TSUYOSHI , WATATANI YASUO 
Published: September 2007

AbstractWe completely classify the Kubo–Martin–Schwinger (KMS) states for the gauge action on aC*-algebra associated with a rational functionRintroduced in our previous work. The gauge action has a phase transition atβ=log degR. We can recover the degree ofR, the number of branched points, the number of exceptional points and the orbits of exceptional points from the structure of the KMS states. We also classify the KMS states forC*-algebras associated with some self-similar sets, including the full tent map and the Sierpinski gasket by a similar method.
An example of how the Ricci flow can increase topological entropy
Authors: JANE DAN 
Published: September 2007

AbstractWe give a surface for which the Ricci flow applied to the metric will increase the topological entropy of the geodesic flow. Specifically, we first adapt the Melnikov method to apply to a Ricci flow perturbation and then we construct a surface which is closely related to a surface of revolution, but does not quite have rotational symmetry. This is done by adapting the Liouville metric representation of a surface of revolution. The final steps of the Melnikov method require numerical integration.
Measure rigidity for algebraic bipermutative cellular automata
Authors: SABLIK MATHIEU 
Published: September 2007

AbstractLet $({\mathcal {A}^{\mathbb {Z}}} ,F)$ be a bipermutative algebraic cellular automaton. We present conditions that force a probability measure, which is invariant for the $ {\mathbb {N}} \times {\mathbb {Z}} $-action of F and the shift map σ, to be the Haar measure on Σ, a closed shift-invariant subgroup of the abelian compact group $ {\mathcal {A}^{\mathbb {Z}}} $. This generalizes simultaneously results of Host et al (B. Host, A. Maass and S. Martínez. Uniform Bernoulli measure in dynamics of permutative cellular automata with algebraic local rules. Discrete Contin. Dyn. Syst. 9(6) (2003), 1423–1446) and Pivato (M. Pivato. Invariant measures for bipermutative cellular automata. Discrete Contin. Dyn. Syst. 12(4) (2005), 723–736). This result is applied to give conditions which also force an (F,σ)-invariant probability measure to be the uniform Bernoulli measure when F is a particular invertible affine expansive cellular automaton on $ {\mathcal {A}^{\mathbb {N}}} $.
Algebraic methods in mechanism analysis and synthesis
Authors: Husty Manfred L. , Pfurner Martin , Schröcker Hans-Peter , Brunnthaler Katrin 
Published: September 2007

SUMMARYAlgebraic methods in connection with classical multidimensional geometry have proven to be very efficient in the computation of direct and inverse kinematics of mechanisms as well as the explanation of strange, pathological behavior. In this paper, we give an overview of the results achieved within the last few years using the algebraic geometric method, geometric preprocessing, and numerical analysis. We provide the mathematical and geometrical background, like Study's parametrization of the Euclidean motion group, the ideals belonging to mechanism constraints, and methods to solve polynomial equations. The methods are explained with different examples from mechanism analysis and synthesis.
Singular curves in the joint space and cusp points of 3-R

P

R parallel manipulators
Authors: Zein Mazen , Wenger Philippe , Chablat Damien 
Published: September 2007

SUMMARYThis paper investigates the singular curves in the joint space of a family of planar parallel manipulators. It focuses on special points, referred to as cusp points, which may appear on these curves. Cusp points play an important role in the kinematic behavior of parallel manipulators since they make possible a nonsingular change of assembly mode. The purpose of this study is twofold. First, it exposes a method to compute joint space singular curves of 3-RPR planar parallel manipulators. Second, it presents an algorithm for detecting and computing all cusp points in the joint space of these same manipulators.