4,175 research outputs found
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Landscape context mediates the relationship between plant functional traits and decomposition
Aims: It has been well demonstrated that several interacting endogenous and exogenous factors influence decomposition. However, teasing apart the direct and indirect effects of these factors to predict decomposition patterns in heterogenous landscapes remains a key challenge. Methods: At 157 locations in a temperate forest, we measured decomposition of a standard substrate (filter paper) over two years, the landscape context in which decomposition took place, and the functional composition of the woody species that contributed leaf litter to the forest floor where litter bags were placed. We tested for direct and indirect effects of landscape context and direct effects of forest functional composition on decay using structural equation modelling. Results: We found that landscape context had direct effects on decay and indirect effects on decay via its influence on the functional composition of the surrounding forest. Forest functional composition also had direct effects on decay, but these effects decreased or disappeared completely over time. Moreover, community weighted mean trait values were better predictors of decay than functional dispersion of leaf traits, and leaf nitrogen content and carbon content were better predictors of decay than leaf dry matter content or leaf toughness. Conclusions: Our results highlight the importance of an integrative approach that examines the direct and indirect effects of multiple factors for understanding and predicting decomposition patterns across heterogenous landscapes
Real-time national GPS networks: Opportunities for atmospheric sensing
Real-time national Global Positioning System (GPS) networks are being established in a number of countries for atmospheric sensing. UCAR, in collaboration with participating universities, is developing one of these networks in the United States. The network, named "SuomiNet" to honor meteorological satellite pioneer Verner Suomi, is funded by the U.S. National Science Foundation. SuomiNet will exploit the recently-shown ability of ground-based GPS receivers to make thousands of accurate upper and lower atmospheric measurements per day. Phase delays induced in GPS signals by the ionosphere and neutral atmosphere can be measured with high precision simultaneously along up to a dozen GPS ray paths in the field of view. These delays can be converted into total electron content (TEC), and integrated water vapor (if surface pressure data or estimates are available), along each GPS ray path. The resulting continuous, accurate, all-weather, real-time upper and lower atmospheric data create a variety of opportunities for atmospheric research. In this letter we describe SuomiNet, its applications, and the opportunity to coordinate national real-time GPS networks to create, a global network with larger scientific and operational potential. Copy right© The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS); The Seismological Society of Japan; The Volcanological Society of Japan; The Geodetic Society of Japan; The Japanese Society for Planetary Sciences
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Impact of obsessive-compulsive personality disorder (OCPD) symptoms in Internet users
Background: Internet use is pervasive in many cultures. Little is known about the impact of Obsessive-Compulsive Personality Disorder (OCPD) symptoms on impulsive and compulsive psychopathologies in people who use the Internet.
Method: 1323 adult Internet users completed an online questionnaire quantifying OCPD symptoms, likely occurrence of select mental disorders (OCD, ADHD, problematic Internet use, anxiety), and personality questionnaires of impulsivity (Barratt) and compulsivity (Padua). Predictors of presence of OCPD symptoms (endorsement of at least 4 of 8 DSM criteria) were identified using binary logistic regression.
Results: In regression (p<0.001, AUC 0.77), OCPD symptoms were significantly associated with (in order of decreasing effect size): lower non-planning impulsivity, higher ADHD symptoms, problematic Internet use, avoidant personality disorder, female gender, generalized anxiety disorder, and some types of compulsions (checking, dressing/washing).
Conclusions: These data suggest that OCPD symptoms, defined in terms of at least 4 of 8 DSM tick-list criteria being met, are common in Internet users. OCPD symptoms were associated with considerably higher levels of psychopathology relating to both impulsive (ADHD) and compulsive (OC-related and problematic Internet use) disorders. These data merit replication and extension using gold-standard in-person clinical assessments, as the current study relied on self-report over the Internet.This research was supported by a Grant from the Academy of Medical Sciences (UK) and by a Wellcome Trust Clinical Fellowship (110049/Z/15/Z)
Frustration and thermalization in an artificial magnetic quasicrystal
Artificial frustrated systems offer a playground to study the emergent properties of interacting systems. Most work to date has been on spatially periodic systems, known as artificial spin ices when the interacting elements are magnetic. Here we have studied artificial magnetic quasicrystals based on quasiperiodic Penrose tiling patterns of interacting nanomagnets. We construct a low-energy configuration from a step-by-step approach that we propose as a ground state. Topologically induced emergent frustration means that this configuration cannot be constructed from vertices in their ground states. It has two parts, a quasi-one-dimensional ‘skeleton’ that spans the entire pattern and is capable of long-range order, surrounding ‘flippable’ clusters of macrospins that lead to macroscopic degeneracy. Magnetic force microscopy imaging of Penrose tiling arrays revealed superdomains that are larger for more strongly coupled arrays, especially after annealing the array above its blocking temperature
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Correction to: Real-time national GPS networks: opportunities for atmospheric sensing (Earth, Planets and Space, (2000), 52, 11, (901-905), 10.1186/BF03352303)
Portions of this letter come from the content published in the paper by Ware et al. [1]
On the back reaction of gravitational and particle emission and absorption from straight thick cosmic strings: A toy model
The emission and absorption of gravitational waves and massless particles of
an infinitely long straight cosmic string with finite thickness are studied. It
is shown in a general term that the back reaction of the emission and
absorption {\em always} makes the symmetry axis of the string singular. The
singularity is a scalar singularity and cannot be removed.Comment: To appear in Gen. Relativ. Gra
Patient factors associated with non-attendance at colonoscopy after a positive screening faecal occult blood test
BACKGROUND: Screening participants with abnormal faecal occult blood test results who do not attend further testing are at high risk of colorectal cancer, yet little is known about their reasons for non-attendance. METHODS: We conducted a medical record review of 170 patients from two English Bowel Cancer Screening Programme centres who had abnormal guaiac faecal occult blood test screening tests between November 2011 and April 2013 but did not undergo colonoscopy. Using information from patient records, we coded and categorized reasons for non-attendance. RESULTS: Of the 170 patients, 82 were eligible for review, of whom 66 had at least one recorded reason for lack of colonoscopy follow-up. Reasons fell into seven main categories: (i) other commitments, (ii) unwillingness to have the test, (iii) a feeling that the faecal occult blood test result was a false positive, (iv) another health issue taking priority, (v) failing to complete bowel preparation, (vi) practical barriers (e.g. lack of transport), and (vii) having had or planning colonoscopy elsewhere. The most common single reasons were unwillingness to have a colonoscopy and being away. CONCLUSIONS: We identify a range of apparent reasons for colonoscopy non-attendance after a positive faecal occult blood test screening. Education regarding the interpretation of guaiac faecal occult blood test findings, offer of alternative confirmatory test options, and flexibility in the timing or location of subsequent testing might decrease non-attendance of diagnostic testing following positive faecal occult blood test
Kerr-AdS and its Near-horizon Geometry: Perturbations and the Kerr/CFT Correspondence
We investigate linear perturbations of spin-s fields in the Kerr-AdS black
hole and in its near-horizon geometry (NHEK-AdS), using the Teukolsky master
equation and the Hertz potential. In the NHEK-AdS geometry we solve the
associated angular equation numerically and the radial equation exactly. Having
these explicit solutions at hand, we search for linear mode instabilities. We
do not find any (non-)axisymmetric instabilities with outgoing boundary
conditions. This is in agreement with a recent conjecture relating the
linearized stability properties of the full geometry with those of its
near-horizon geometry. Moreover, we find that the asymptotic behaviour of the
metric perturbations in NHEK-AdS violates the fall-off conditions imposed in
the formulation of the Kerr/CFT correspondence (the only exception being the
axisymmetric sector of perturbations).Comment: 26 pages. 4 figures. v2: references added. matches published versio
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