2,368 research outputs found
Congruent families and invariant tensors
Classical results of Chentsov and Campbell state that -- up to constant
multiples -- the only -tensor field of a statistical model which is
invariant under congruent Markov morphisms is the Fisher metric and the only
invariant -tensor field is the Amari-Chentsov tensor. We generalize this
result for arbitrary degree , showing that any family of -tensors which
is invariant under congruent Markov morphisms is algebraically generated by the
canonical tensor fields defined in an earlier paper
The wavelet-NARMAX representation : a hybrid model structure combining polynomial models with multiresolution wavelet decompositions
A new hybrid model structure combing polynomial models with multiresolution wavelet decompositions is introduced for nonlinear system identification. Polynomial models play an important role in approximation theory, and have been extensively used in linear and nonlinear system identification. Wavelet decompositions, in which the basis functions have the property of localization in both time and frequency, outperform many other approximation schemes and offer a flexible solution for approximating arbitrary functions. Although wavelet representations can approximate even severe nonlinearities in a given signal very well, the advantage of these representations can be lost when wavelets are used to capture linear or low-order nonlinear behaviour in a signal. In order to sufficiently utilise the global property of polynomials and the local property of wavelet representations simultaneously, in this study polynomial models and wavelet decompositions are combined together in a parallel structure to represent nonlinear input-output systems. As a special form of the NARMAX model, this hybrid model structure will be referred to as the WAvelet-NARMAX model, or simply WANARMAX. Generally, such a WANARMAX representation for an input-output system might involve a large number of basis functions and therefore a great number of model terms. Experience reveals that only a small number of these model terms are significant to the system output. A new fast orthogonal least squares algorithm, called the matching pursuit orthogonal least squares (MPOLS) algorithm, is also introduced in this study to determine which terms should be included in the final model
NLO forward-backward charge asymmetries in p p (p bar p) -> l- l+ jet production at large hadron colliders
We consider the next-to-leading order corrections, O(alpha_s), to
forward-backward charge asymmetries for lepton-pair production in association
with a large transverse momentum jet at large hadron colliders. We find that
the leading order results are essentially confirmed. Although experimentally
challenging and in practice with large backgrounds, these observables could
provide a new determination of the weak mixing angle sin2 theta^lept_eff
(M_Z^2) with a statistical precision for each lepton flavour of ~10^(-3) (7 x
10^{-3}) at LHC (Tevatron), and if b jets are identified, of the b quark Z
asymmetry A^b_{FB} with a statistical precision of ~ 2x10^{-3} (4x10{-2}) at
LHC (Tevatron).Comment: 16 pages, version to appear in Physics Letters
And now for something completely different: Visual novelty in an online network of designers
Novelty is a key ingredient of innovation but quantifying it is difficult.
This is especially true for visual work like graphic design. Using designs
shared on an online social network of professional digital designers, we
measure visual novelty using statistical learning methods to compare an images
features with those of images that have been created before. We then relate
social network position to the novelty of the designers images. We find that on
this professional platform, users with dense local networks tend to produce
more novel but generally less successful images, with important exceptions.
Namely, users making novel images while embedded in cohesive local networks are
more successful.Comment: accepted to 10th International ACM Web Science Conference, 2018, May
27-30, Amsterdam, The Netherlands, 11 pages, 6 figures, 60 reference
Effectiveness of guided self-help in decreasing expressed emotion in family caregivers of people diagnosed with depression in Thailand: a randomised controlled trial
Background: High expressed emotion (EE) can extend the duration of illness and precipitate relapse; however, little evidence-based information is available to assist family caregivers of individuals with depression. In the present exploratory study, we examined the effectiveness of a cognitive behaviour therapy (CBT) based guided self-help (GSH) manual in decreasing EE in caregivers of people with depression, in Thailand.
Method: A parallel group randomised controlled trial was conducted, following CONSORT guidelines, with 54 caregivers who were allocated equally to GSH or control group (standard outpatient department support). In addition, both groups were contacted weekly by telephone. EE was assessed, using the Family Questionnaire (FQ), at baseline, post-test (Week 8) and follow-up (Week 12).
Results: FQ scores at baseline indicated that both groups had similar, though moderately high level of EE. However, between baseline and post-test EE scores decreased markedly in the intervention group, but in contrast, they increased slightly in the control group. Between post-test and follow-up, little change took place in the EE scores of either group. Overall, the intervention group recipients of GSH showed a significant decrease in EE whereas the control group recipients of standard outpatient department support reported a slight increase in EE.
Conclusion: These findings provide preliminary evidence that GSH is beneficial in reducing EE in caregivers, which is advantageous to family members with depression and caregivers. The approach may be used as an adjunct to the limited outpatient department support given to caregivers by mental health professionals and, perhaps, to caregivers who do not attend these departments
The effect of exposure to synthetic pheromone lures on male Zygaena filipendulae mating behaviour: implications for monitoring species of conservation interest
Pheromone based monitoring of insects of conservation value has the potential to revolutionise the way in which surveys are carried out. However, due to their effective use in pest management, concerns have been raised about potential negative effects of pheromone exposure on populations of rare insects. The effect of exposure to synthetic pheromone lures on male mating behaviour was examined in laboratory and field conditions using the six spot burnet moth Zygaena filipendulae (Linnaeus, 1758). For the laboratory experiment larvae were collected and cultured separately under controlled conditions. Virgin males were exposed to a synthetic pheromone lure for 24 h; then tested for responsiveness immediately after this exposure, 1 and 24 h later. Control males were tested three times: initially, 1 h later and 24 h later. The time taken for males to detect females, shown by exposure of their anal claspers, and the time taken for males to locate females were recorded. No significant difference was found between the time taken for control and exposed males to detect or locate females, and no significant difference between the proportions of males that successfully located females in exposed and control groups was found. In the field experiment the time males spent in the presence of contained females, both with and without a pheromone lure present, was recorded. Males spent more time in the presence of the females when the pheromone lure was present. Both experiments indicate male Z. filipendulae mating behaviour is not adversely affected by exposure to synthetic pheromone lures
Protocol for the 'e-Nudge trial' : a randomised controlled trial of electronic feedback to reduce the cardiovascular risk of individuals in general practice [ISRCTN64828380]
Background: Cardiovascular disease (including coronary heart disease and stroke) is a major
cause of death and disability in the United Kingdom, and is to a large extent preventable, by lifestyle
modification and drug therapy. The recent standardisation of electronic codes for cardiovascular
risk variables through the United Kingdom's new General Practice contract provides an
opportunity for the application of risk algorithms to identify high risk individuals. This randomised
controlled trial will test the benefits of an automated system of alert messages and practice
searches to identify those at highest risk of cardiovascular disease in primary care databases.
Design: Patients over 50 years old in practice databases will be randomised to the intervention
group that will receive the alert messages and searches, and a control group who will continue to
receive usual care. In addition to those at high estimated risk, potentially high risk patients will be
identified who have insufficient data to allow a risk estimate to be made. Further groups identified
will be those with possible undiagnosed diabetes, based either on elevated past recorded blood
glucose measurements, or an absence of recent blood glucose measurement in those with
established cardiovascular disease.
Outcome measures: The intervention will be applied for two years, and outcome data will be
collected for a further year. The primary outcome measure will be the annual rate of cardiovascular
events in the intervention and control arms of the study. Secondary measures include the
proportion of patients at high estimated cardiovascular risk, the proportion of patients with missing
data for a risk estimate, and the proportion with undefined diabetes status at the end of the trial
Factorization and resummation of s-channel single top quark production
In this paper we study the factorization and resummation of s-channel single
top quark production in the Standard Model at both the Tevatron and the LHC. We
show that the production cross section in the threshold limit can be factorized
into a convolution of hard function, soft function and jet function via
soft-collinear-effective-theory (SCET), and resummation can be performed using
renormalization group equation in the momentum space resummation formalism. We
find that in general, the resummation effects enhance the Next-to-Leading-Order
(NLO) cross sections by about at both the Tevatron and the LHC, and
significantly reduce the factorization scale dependence of the total cross
section at the Tevatron, while at the LHC we find that the factorization scale
dependence has not been improved, compared with the NLO results.Comment: 29 pages, 7 figures; version published in JHE
Female partners of patients after surgical prostate cancer treatment: interactions with physicians and support needs
<p>Abstract</p> <p>Background</p> <p>Few studies have explored the women's experiences as a result of a partners' diagnosis of prostate cancer. This study begins to explore women's interactions with physicians (primary care and urologist) and the support needs associated with the diagnosis and treatment of their partners' prostate cancer.</p> <p>Methods</p> <p>Two focus groups (n = 14) of women whose partners were diagnosed with prostate cancer (diagnoses' 1 - 18 months). A trained facilitator used open-ended questions to explore ideas. The framework approach was used to analyze the transcripts.</p> <p>Results</p> <p>Three main themes emerged: 1. <b>More support</b>. Validation and information is needed for women including emotional support and opportunities to share experiences. 2. <b>Role of the physician</b>. The transfer of care once specialized treatment is no longer needed remained poorly defined, which increased confusion and feelings of abandonment related to the role of the primary physician. 3. <b>Partners' relationship changes</b>. Men became more dependent on their partners for support and to act as the primary communicator and caregiver.</p> <p>Conclusions</p> <p>Additional research is needed in this field to confirm the importance of training primary care physicians to consider holistic treatment approaches that recognize the partner and family needs as important in the complete physical and emotional healing of their patients.</p
- …