238 research outputs found
A new method for automatic Multiple Partial Discharge Classification
A new wavelet based feature parameter have been developed to represent the characteristics of PD activities, i.e. the wavelet decomposition energy of PD pulses measured from non-conventional ultra wide bandwidth PD sensors such as capacitive couplers (CC) or high frequency current transformers (HFCT). The generated feature vectors can contain different dimensions depending on the length of recorded pulses. These high dimensional feature vectors can then be processed using Principal Component Analysis (PCA) to map the data into a three dimensional space whilst the first three most significant components representing the feature vector are preserved. In the three dimensional mapped space, an automatic Density-Based Spatial Clustering of Applications with Noise (DBSCAN) algorithm is then applied to classify the data cluster(s) produced by the PCA. As the procedure is undertaken in a three dimensional space, the obtained clustering results can be easily assessed. The classified PD sub-data sets are then reconstructed in the time domain as phase-resolved patterns to facilitate PD source type identification. The proposed approach has been successfully applied to PD data measured from electrical machines and power cables where measurements were undertaken in different laboratories
Histiocytic Sarcoma in a Kidney Transplant Patient: A Case Report and Review of the Literature
Objective. Histiocytic sarcoma (HS) is an aggressive neoplasm with only limited number of reported series of cases and rare case reports of occurrence as a posttransplant neoplastic disorder. The etiology and pathogenesis of the disease is unknown and the optimal treatment is still under investigation. We describe an unusual case of HS in a patient with a remote history of kidney transplant. Method and Results. A 54-year-old male with a remote history of renal transplantation under maintenance immunosuppression presented with features of sepsis. CT abdomen revealed multiple heterogeneous masses in bilateral native kidneys and liver and enlarged abdominal and retroperitoneal lymph nodes. Viral serology work-up was negative. Needle core biopsy revealed a highly undifferentiated neoplasm comprised of highly atypical large cells with eosinophilic to vacuolated cytoplasm and hemophagocytosis. Extended panel of immunohistochemistry proved histiocytic lineage for the tumor cells. The patient expired 2 weeks following the diagnosis. Conclusion. Our case along with three previously published case reports raised the possibility of HS as a treatment-related neoplasm or a posttransplantation neoplastic disorder in solid organ transplant recipients
The clinical and cost burden of coronary calcification in a Medicare cohort: An economic model to address under-reporting and misclassification
AbstractBackgroundCoronary artery calcification (CAC) is a well-established risk factor for the occurrence of adverse ischemic events. However, the economic impact of the presence of CAC is unknown.ObjectivesThrough an economic model analysis, we sought to estimate the incremental impact of CAC on medical care costs and patient mortality for de novo percutaneous coronary intervention (PCI) patients in the 2012 cohort of the Medicare elderly (â„65) population.MethodsThis aggregate burden-of-illness study is incidence-based, focusing on cost and survival outcomes for an annual Medicare cohort based on the recently introduced ICD9 code for CAC. The cost analysis uses a one-year horizon, and the survival analysis considers lost life years and their economic value.ResultsFor calendar year 2012, an estimated 200,945 index (de novo) PCI procedures were performed in this cohort. An estimated 16,000 Medicare beneficiaries (7.9%) were projected to have had severe CAC, generating an additional cost in the first year following their PCI of 56 million in total. In terms of mortality, the model projects that an additional 397 deaths would be attributable to severe CAC in 2012, resulting in 3770 lost life years, representing an estimated loss of about 100,000 each.ConclusionsThese model-based CAC estimates, considering both moderate and severe CAC patients, suggest an annual burden of illness approaching $1.3 billion in this PCI cohort. The potential clinical and cost consequences of CAC warrant additional clinical and economic attention not only on PCI strategies for particular patients but also on reporting and coding to achieve better evidence-based decision-making
TSIL: a program for the calculation of two-loop self-energy integrals
TSIL is a library of utilities for the numerical calculation of dimensionally
regularized two-loop self-energy integrals. A convenient basis for these
functions is given by the integrals obtained at the end of O.V. Tarasov's
recurrence relation algorithm. The program computes the values of all of these
basis functions, for arbitrary input masses and external momentum. When
analytical expressions in terms of polylogarithms are available, they are used.
Otherwise, the evaluation proceeds by a Runge-Kutta integration of the coupled
first-order differential equations for the basis integrals, using the external
momentum invariant as the independent variable. The starting point of the
integration is provided by known analytic expressions at (or near) zero
external momentum. The code is written in C, and may be linked from C, C++, or
Fortran. A Fortran interface is provided. We describe the structure and usage
of the program, and provide a simple example application. We also compute two
new cases analytically, and compare all of our notations and conventions for
the two-loop self-energy integrals to those used by several other groups.Comment: 31 pages. Updated to reflect new functionality through v1.4 May 2016
and new information about use with C++. Source code and documentation are
available at http://www.niu.edu/spmartin/TSIL or
http://faculty.otterbein.edu/DRobertson/tsil
Generalized messengers of supersymmetry breaking and the sparticle mass spectrum
We investigate the sparticle spectrum in models of gauge-mediated
supersymmetry breaking. In these models, supersymmetry is spontaneously broken
at an energy scale only a few orders of magnitude above the electroweak scale.
The breakdown of supersymmetry is communicated to the standard model particles
and their superpartners by "messenger" fields through their ordinary gauge
interactions. We study the effects of a messenger sector in which the
supersymmetry-violating F-term contributions to messenger scalar masses are
comparable to the supersymmetry-preserving ones. We also argue that it is not
particularly natural to restrict attention to models in which the messenger
fields lie in complete SU(5) GUT multiplets, and we identify a much larger
class of viable models. Remarkably, however, we find that the superpartner mass
parameters in these models are still subject to many significant contraints.Comment: 24 pages, LaTeX, uses epsf.sty, 4 figures. Assumptions clarified,
numerical bounds tweaked, typos correcte
Two-Loop g -> gg Splitting Amplitudes in QCD
Splitting amplitudes are universal functions governing the collinear behavior
of scattering amplitudes for massless particles. We compute the two-loop g ->
gg splitting amplitudes in QCD, N=1, and N=4 super-Yang-Mills theories, which
describe the limits of two-loop n-point amplitudes where two gluon momenta
become parallel. They also represent an ingredient in a direct x-space
computation of DGLAP evolution kernels at next-to-next-to-leading order. To
obtain the splitting amplitudes, we use the unitarity sewing method. In
contrast to the usual light-cone gauge treatment, our calculation does not rely
on the principal-value or Mandelstam-Leibbrandt prescriptions, even though the
loop integrals contain some of the denominators typically encountered in
light-cone gauge. We reduce the integrals to a set of 13 master integrals using
integration-by-parts and Lorentz invariance identities. The master integrals
are computed with the aid of differential equations in the splitting momentum
fraction z. The epsilon-poles of the splitting amplitudes are consistent with a
formula due to Catani for the infrared singularities of two-loop scattering
amplitudes. This consistency essentially provides an inductive proof of
Catani's formula, as well as an ansatz for previously-unknown 1/epsilon pole
terms having non-trivial color structure. Finite terms in the splitting
amplitudes determine the collinear behavior of finite remainders in this
formula.Comment: 100 pages, 33 figures. Added remarks about leading-transcendentality
argument of hep-th/0404092, and additional explanation of cut-reconstruction
uniquenes
Two-Loop Helicity Amplitudes for Quark-Quark Scattering in QCD and Gluino-Gluino Scattering in Supersymmetric Yang-Mills Theory
We present the two-loop QCD helicity amplitudes for quark-quark and
quark-antiquark scattering. These amplitudes are relevant for
next-to-next-to-leading order corrections to (polarized) jet production at
hadron colliders. We give the results in the `t Hooft-Veltman and
four-dimensional helicity (FDH) variants of dimensional regularization and
present the scheme dependence of the results. We verify that the finite
remainder, after subtracting the divergences using Catani's formula, are in
agreement with previous results. We also provide the amplitudes for
gluino-gluino scattering in pure N=1 supersymmetric Yang-Mills theory. We
describe ambiguities in continuing the Dirac algebra to D dimensions, including
ones which violate fermion helicity conservation. The finite remainders after
subtracting the divergences using Catani's formula, which enter into physical
quantities, are free of these ambiguities. We show that in the FDH scheme, for
gluino-gluino scattering, the finite remainders satisfy the expected
supersymmetry Ward identities.Comment: arXiv admin note: substantial text overlap with arXiv:hep-ph/030416
Sources of Community Health Worker Motivation: A Qualitative Study in Morogoro Region, Tanzania.
There is a renewed interest in community health workers (CHWs) in Tanzania, but also a concern that low motivation of CHWs may decrease the benefits of investments in CHW programs. This study aimed to explore sources of CHW motivation to inform programs in Tanzania and similar contexts. We conducted semi-structured interviews with 20 CHWs in Morogoro Region, Tanzania. Interviews were digitally recorded, transcribed, and coded prior to translation and thematic analysis. The authors then conducted a literature review on CHW motivation and a framework that aligned with our findings was modified to guide the presentation of results. Sources of CHW motivation were identified at the individual, family, community, and organizational levels. At the individual level, CHWs are predisposed to volunteer work and apply knowledge gained to their own problems and those of their families and communities. Families and communities supplement other sources of motivation by providing moral, financial, and material support, including service fees, supplies, money for transportation, and help with farm work and CHW tasks. Resistance to CHW work exhibited by families and community members is limited. The organizational level (the government and its development partners) provides motivation in the form of stipends, potential employment, materials, training, and supervision, but inadequate remuneration and supplies discourage CHWs. Supervision can also be dis-incentivizing if perceived as a sign of poor performance. Tanzanian CHWs who work despite not receiving a salary have an intrinsic desire to volunteer, and their motivation often derives from support received from their families when other sources of motivation are insufficient. Policy-makers and program managers should consider the burden that a lack of remuneration imposes on the families of CHWs. In addition, CHWs' intrinsic desire to volunteer does not preclude a desire for external rewards. Rather, adequate and formal financial incentives and in-kind alternatives would allow already-motivated CHWs to increase their commitment to their work
A missing operationalization: entrepreneurial competencies in multinational enterprise subsidiaries
We seek to provide a comprehensive operationalization of firm-specific variables that constitute multinational enterprise subsidiary entrepreneurial competencies. Towards this objective, we bring together notions from the fields of entrepreneurship and international business. Drawing on an empirical study of 260 subsidiaries located in the UK, we propose a comprehensive set of scales encompassing innovativeness, risk-taking, proactiveness, learning, intra-multinational networking, extra-multinational networking and autonomy; which capture distinct subsidiary entrepreneurial competencies at the subsidiary level. Research and managerial implications are discussed
Two-Loop Helicity Amplitudes for Quark-Gluon Scattering in QCD and Gluino-Gluon Scattering in Supersymmetric Yang-Mills Theory
We present the two-loop QCD helicity amplitudes for quark-gluon scattering,
and for quark-antiquark annihilation into two gluons. These amplitudes are
relevant for next-to-next-to-leading order corrections to (polarized) jet
production at hadron colliders. We give the results in the `t Hooft-Veltman and
four-dimensional helicity (FDH) variants of dimensional regularization. The
transition rules for converting the amplitudes between the different variants
are much more intricate than for the previously discussed case of gluon-gluon
scattering. Summing our two-loop expressions over helicities and colors, and
converting to conventional dimensional regularization, gives results in
complete agreement with those of Anastasiou, Glover, Oleari and Tejeda-Yeomans.
We describe the amplitudes for 2 to 2 scattering in pure N=1 supersymmetric
Yang-Mills theory, obtained from the QCD amplitudes by modifying the color
representation and multiplicities, and verify supersymmetry Ward identities in
the FDH scheme.Comment: 77 pages. v2: corrected errors in eqs. (3.7) and (3.8) for one-loop
assembly; remaining results unaffecte
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