2,953 research outputs found
On Iterated Twisted Tensor Products of Algebras
We introduce and study the definition, main properties and applications of
iterated twisted tensor products of algebras, motivated by the problem of
defining a suitable representative for the product of spaces in noncommutative
geometry. We find conditions for constructing an iterated product of three
factors, and prove that they are enough for building an iterated product of any
number of factors. As an example of the geometrical aspects of our
construction, we show how to construct differential forms and involutions on
iterated products starting from the corresponding structures on the factors,
and give some examples of algebras that can be described within our theory. We
prove a certain result (called ``invariance under twisting'') for a twisted
tensor product of two algebras, stating that the twisted tensor product does
not change when we apply certain kind of deformation. Under certain conditions,
this invariance can be iterated, containing as particular cases a number of
independent and previously unrelated results from Hopf algebra theory.Comment: 44 pages, 21 figures. More minor typos corrections, one more example
and some references adde
Testing for Network and Spatial Autocorrelation
Testing for dependence has been a well-established component of spatial
statistical analyses for decades. In particular, several popular test
statistics have desirable properties for testing for the presence of spatial
autocorrelation in continuous variables. In this paper we propose two
contributions to the literature on tests for autocorrelation. First, we propose
a new test for autocorrelation in categorical variables. While some methods
currently exist for assessing spatial autocorrelation in categorical variables,
the most popular method is unwieldy, somewhat ad hoc, and fails to provide
grounds for a single omnibus test. Second, we discuss the importance of testing
for autocorrelation in data sampled from the nodes of a network, motivated by
social network applications. We demonstrate that our proposed statistic for
categorical variables can both be used in the spatial and network setting
A preliminary study of the effect of closed incision management with negative pressure wound therapy over high-risk incisions
Background
Certain postoperative wounds are recognised to be associated with more complications than others and may be termed high-risk. Wound healing can be particularly challenging following high-energy trauma where wound necrosis and infection rates are high. Surgical incision for joint arthrodesis can also be considered high-risk as it requires extensive and invasive surgery and postoperative distal limb swelling and wound dehiscence are common. Recent human literature has investigated the use of negative pressure wound therapy (NPWT) over high-risk closed surgical incisions and beneficial effects have been noted including decreased drainage, decreased dehiscence and decreased infection rates. In a randomised, controlled study twenty cases undergoing distal limb high-energy fracture stabilisation or arthrodesis were randomised to NPWT or control groups. All cases had a modified Robert-Jones dressing applied for 72 h postoperatively and NPWT was applied for 24 h in the NPWT group. Morphometric assessment of limb circumference was performed at six sites preoperatively, 24 and 72 h postoperatively. Wound discharge was assessed at 24 and 72 h. Postoperative analgesia protocol was standardised and a Glasgow Composite Measure Pain Score (GCPS) carried out at 24, 48 and 72 h. Complications were noted and differences between groups were assessed.
Results
Percentage change in limb circumference between preoperative and 24 and 72 h postoperative measurements was significantly less at all sites for the NPWT group with exception of the joint proximal to the surgical site and the centre of the operated bone at 72 h. Median discharge score was lower in the NPWT group than the control group at 24 h. No significant differences in GCPS or complication rates were noted.
Conclusions
Digital swelling and wound discharge were reduced when NPWT was employed for closed incision management. Larger studies are required to evaluate whether this will result in reduced discomfort and complication rates postoperatively
Variations in Pastorsâ Perceptions of the Etiology of Depression By Race and Religious Affiliation
Depression is a major, preventable problem in the United States, yet relatively few individuals seek care in traditional mental health settings. Instead, many choose to confide in friends, family, or clergy. Thus, it is important to discover how clergy perceive the definition of and etiology of depression. The author conducted a survey with 204 Protestant pastors in California. Multinomial logistic regression revealed a statistically significant difference in how depression is perceived based on race. Caucasian American pastors more readily agreed with the statement that depression was a biological mood disorder, while African American pastors more readily agreed that depression was a moment of weakness when dealing with trials and tribulations. Also, mainline Protestants more frequently disagreed with statements about spiritual causes of depression than Pentecostals and non-denominational pastors. The findings suggest that racial and religious affiliational influences shape how pastors view, and ultimately intervene, in the area of depression
Relativistic Corrections to the Triton Binding Energy
The influence of relativity on the triton binding energy is investigated. The
relativistic three-dimensional version of the Bethe-Salpeter equation proposed
by Blankenbecler and Sugar (BbS) is used. Relativistic (non-separable)
one-boson-exchange potentials (constructed in the BbS framework) are employed
for the two-nucleon interaction. In a 34-channel Faddeev calculation, it is
found that relativistic effects increase the triton binding energy by about 0.2
MeV. Including charge-dependence (besides relativity), the final triton binding
energy predictions are 8.33 and 8.16 MeV for the Bonn A and B potential,
respectively.Comment: 25 pages of text (latex), 1 figure (not included, available upon
request
Momentum and Coordinate Space Three-nucleon Potentials
In this paper we give explicit formulae in momentum and coordinate space for
the three-nucleon potentials due to and meson exchange, derived
from off-mass-shell meson-nucleon scattering amplitudes which are constrained
by the symmetries of QCD and by the experimental data. Those potentials have
already been applied to nuclear matter calculations. Here we display additional
terms which appear to be the most important for nuclear structure. The
potentials are decomposed in a way that separates the contributions of
different physical mechanisms involved in the meson-nucleon amplitudes. The
same type of decomposition is presented for the TM force: the
, the chiral symmetry breaking and the nucleon pair terms are isolated.Comment: LATEX, 33 pages, 3 figures (available as postscript files upon
request
Present and Future Bounds on Non-Standard Neutrino Interactions
We consider Non-Standard neutrino Interactions (NSI), described by
four-fermion operators of the form , where is an electron or first generation quark. We
assume these operators are generated at dimension , so the related
vertices involving charged leptons, obtained by an SU(2) transformation
, do not appear at tree level. These related
vertices necessarily arise at one loop, via exchange. We catalogue current
constraints from measurements in neutrino scattering, from
atmospheric neutrino observations, from LEP, and from bounds on the related
charged lepton operators. We estimate future bounds from comparing KamLAND and
solar neutrino data, and from measuring at the near detector
of a neutrino factory. Operators constructed with and should
not confuse the determination of oscillation parameters at a factory,
because the processes we consider are more sensitive than oscillations at the
far detector. For operators involving , we estimate similar
sensitivities at the near and far detector.Comment: Erratum added at the end of the documen
Telephone and face to face methods of assessment of veteran's community reintegration yield equivalent results
<p>Abstract</p> <p>Background</p> <p>The Community Reintegration of Service Members (CRIS) is a new measure of community reintegration developed to measure veteran's participation in life roles. It consists of three sub-scales: Extent of Participation (Extent), Perceived Limitations with Participation (Perceived), and Satisfaction with Participation (Satisfaction). Testing of the CRIS measure to date has utilized in-person administration. Administration of the CRIS measure by telephone, if equivalent to in-person administration, would be desirable to lower cost and decrease administrative burden. The purpose of this study was to test the equivalence of telephone and in-person mode of CRIS administration.</p> <p>Methods</p> <p>A convenience sample of 102 subjects (76% male, 24% female, age mean = 49 years, standard deviation = 8.3) were randomly assigned to received either telephone interview at Visit 1 and in-person interview at Visit 2, or in-person interview at Visit 1 and telephone interview a Visit 2. Both Visits were conducted within one week. Intraclass correlation coefficients, ICC (2,1), were used to evaluate correspondence between modes for both item scores and summary scores. ANOVAs with mode order as a covariate were used to test for presence of an ordering effect.</p> <p>Results</p> <p>ICCs (95%CI) for the subscales were 0.92 (0.88-0.94) for Extent, 0.85 (0.80-0.90) for Perceived, and 0.89 (0.84-0.93) for Satisfaction. No ordering effect was observed.</p> <p>Conclusion</p> <p>Telephone administration of the CRIS measure yielded equivalent results to in-person administration. Telephone administration of the CRIS may enable lower costs of administration and greater adoption.</p
First-principles design and subsequent synthesis of a material to search for the permanent electric dipole moment of the electron
We describe the first-principles design and subsequent synthesis of a new
material with the specific functionalities required for a solid-state-based
search for the permanent electric dipole moment of the electron. We show
computationally that perovskite-structure europium barium titanate should
exhibit the required large and pressure-dependent ferroelectric polarization,
local magnetic moments, and absence of magnetic ordering even at liquid helium
temperature. Subsequent synthesis and characterization of
EuBaTiO ceramics confirm the predicted desirable
properties.Comment: Nature Materials, in pres
ObStruct: A method to objectively analyse factors driving population structure using Bayesian ancestry profiles
Bayesian inference methods are extensively used to detect the presence of population structure given genetic data. The primary output of software implementing these methods are ancestry profiles of sampled individuals. While these profiles robustly partition the data into subgroups, currently there is no objective method to determine whether the fixed factor of interest (e.g. geographic origin) correlates with inferred subgroups or not, and if so, which populations are driving this correlation. We present ObStruct, a novel tool to objectively analyse the nature of structure revealed in Bayesian ancestry profiles using established statistical methods. ObStruct evaluates the extent of structural similarity between sampled and inferred populations, tests the significance of population differentiation, provides information on the contribution of sampled and inferred populations to the observed structure and crucially determines whether the predetermined factor of interest correlates with inferred population structure. Analyses of simulated and experimental data highlight ObStruct's ability to objectively assess the nature of structure in populations. We show the method is capable of capturing an increase in the level of structure with increasing time since divergence between simulated populations. Further, we applied the method to a highly structured dataset of 1,484 humans from seven continents and a less structured dataset of 179 Saccharomyces cerevisiae from three regions in New Zealand. Our results show that ObStruct provides an objective metric to classify the degree, drivers and significance of inferred structure, as well as providing novel insights into the relationships between sampled populations, and adds a final step to the pipeline for population structure analyses. © 2014 Gayevskiy et al
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