523 research outputs found
Aggregated functional data model for Near-Infrared Spectroscopy calibration and prediction
Calibration and prediction for NIR spectroscopy data are performed based on a
functional interpretation of the Beer-Lambert formula. Considering that, for
each chemical sample, the resulting spectrum is a continuous curve obtained as
the summation of overlapped absorption spectra from each analyte plus a
Gaussian error, we assume that each individual spectrum can be expanded as a
linear combination of B-splines basis. Calibration is then performed using two
procedures for estimating the individual analytes curves: basis smoothing and
smoothing splines. Prediction is done by minimizing the square error of
prediction. To assess the variance of the predicted values, we use a
leave-one-out jackknife technique. Departures from the standard error models
are discussed through a simulation study, in particular, how correlated errors
impact on the calibration step and consequently on the analytes' concentration
prediction. Finally, the performance of our methodology is demonstrated through
the analysis of two publicly available datasets.Comment: 27 pages, 7 figures, 7 table
A Systematic Literature Review of the Current State of Knowledge Related to Interventions for Bereaved Parents
Aims:
The purpose of this systematic literature review is to describe the interventions for bereaved parents, evaluate intervention effectiveness through study methodology rigor, replicability, and theoretical foundations.
Methods:
We searched MEDLINE via PubMed (1966-2018), CINAHL (1937-present), PsycINFO (1887-present), and Embase (1947-present) using various search words and MeSH terms related to the study purpose. A blinded screening of title/abstract was performed, with conflicting inclusion decisions resolved through group discussions. Matrices for remaining articles were created and discussed among the team. The levels of evidence of the 9 records were rated from very low to high based on the Grading of Recommendations Assessment, Development, and Evaluation guidelines.
Results:
Our initial pool included 1025 articles. After the screening of titles/abstracts, 63 articles were retained for full-text reviews. Evaluated based on the inclusion/exclusion criteria, 9 records met the review criteria. Of the 9 records, 1 was graded as very low, 3 low, and 5 low to moderate. The interventions for bereaved parents varied from using single-model interventions such as expressive arts therapy and telephone support to multimodal interventions that combined resources (ie, peer support, resource packets, and health-care support). Only 1 study explicitly illustrated how its bereavement intervention was designed based on the proposed theoretical model.
Conclusions:
This review highlights the need for individualized, well-tested, and effective bereavement care interventions to support bereaved parents. In summary, the state of the science on interventions for bereaved parents is poor and much work needs to be done to effectively address the needs of bereaved parents, including both their physical and emotional health needs
Tunable pseudogap Kondo effect and quantum phase transitions in Aharonov-Bohm interferometers
We study two quantum dots embedded in the arms of an Aharonov-Bohm ring
threaded by a magnetic flux. The system can be described by an effective
one-impurity Anderson model with an energy- and flux-dependent density of
states. For specific values of the flux, this density of states vanishes at the
Fermi energy, yielding a controlled realization of the pseudogap Kondo effect.
The conductance and transmission phase shifts reflect a nontrivial interplay
between wave interference and interactions, providing clear signatures of
quantum phase transitions between Kondo and non-Kondo ground states.Comment: Published versio
A Hierarchical Model for Aggregated Functional Data
In many areas of science one aims to estimate latent sub-population mean
curves based only on observations of aggregated population curves. By
aggregated curves we mean linear combination of functional data that cannot be
observed individually. We assume that several aggregated curves with linear
independent coefficients are available. More specifically, we assume each
aggregated curve is an independent partial realization of a Gaussian process
with mean modeled through a weighted linear combination of the disaggregated
curves. We model the mean of the Gaussian processes as a smooth function
approximated by a function belonging to a finite dimensional space
which is spanned by B-splines basis functions. We explore two different
specifications of the covariance function of the Gaussian process: one that
assumes a constant variance across the domain of the process, and a more
general variance structure which is itself modelled as a smooth function,
providing a nonstationary covariance function. Inference procedure is performed
following the Bayesian paradigm allowing experts' opinion to be considered when
estimating the disaggregated curves. Moreover, it naturally provides the
uncertainty associated with the parameters estimates and fitted values. Our
model is suitable for a wide range of applications. We concentrate on two
different real examples: calibration problem for NIR spectroscopy data and an
analysis of distribution of energy among different type of consumers.Comment: 29 pages, 12 figure
Adaptive basis selection for functional data analysis via stochastic penalization
We propose an adaptive method of analyzing a collection of curves which can be, individually, modeled as a linear combination of spline basis functions. Through the introduction of latent Bernoulli variables, the number of basis functions, the variance of the error measurements and the coefficients of the expansion are determined. We provide a modification of the stochastic EM algorithm for which numerical results show that the estimates are very close to the true curve in the sense of L2 norm.We propose an adaptive method of analyzing a collection of curves which can be, individually, modeled as a linear combination of spline basis functions. Through the introduction of latent Bernoulli variables, the number of basis functions, the variance of242209229CNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTĂFICO E TECNOLĂGICOFAPESP - FUNDAĂĂO DE AMPARO Ă PESQUISA DO ESTADO DE SĂO PAULO3000644/94-9; 475763/03-3; 301054/93-201/00258-0; 02/01554-
Signatures of quantum phase transitions in parallel quantum dots: Crossover from local-moment to underscreened spin-1 Kondo physics
We study a strongly interacting "quantum dot 1" and a weakly interacting "dot
2" connected in parallel to metallic leads. Gate voltages can drive the system
between Kondo-quenched and non-Kondo free-moment phases separated by
Kosterlitz-Thouless quantum phase transitions. Away from the immediate vicinity
of the quantum phase transitions, the physical properties retain signatures of
first-order transitions found previously to arise when dot 2 is strictly
noninteracting. As interactions in dot 2 become stronger relative to the
dot-lead coupling, the free moment in the non-Kondo phase evolves smoothly from
an isolated spin-one-half in dot 1 to a many-body doublet arising from the
incomplete Kondo compensation by the leads of a combined dot spin-one. These
limits, which feature very different spin correlations between dot and lead
electrons, can be distinguished by weak-bias conductance measurements performed
at finite temperatures.Comment: 7 pages, 7 figures. Accepted for publication in Phys. Rev.
Zero-field Kondo splitting and quantum-critical transition in double quantum dots
Double quantum dots offer unique possibilities for the study of many-body
correlations. A system containing one Kondo dot and one effectively
noninteracting dot maps onto a single-impurity Anderson model with a structured
(nonconstant) density of states. Numerical renormalization-group calculations
show that while band filtering through the resonant dot splits the Kondo
resonance, the singlet ground state is robust. The system can also be
continuously tuned to create a pseudogapped density of states and access a
quantum critical point separating Kondo and non-Kondo phases.Comment: 4 pages, 4 figures; Accepted for publication in Physical Review
Letter
Bereaved Parentsâ Health Status During the First 6 Months After Their Childâs Death
Purpose:
To examine bereaved parentsâ physical, mental, and social health during the first 6 months after their childâs (<12 years) death from a life-threatening illness.
Background and Significance:
Bereaved parents have higher mortality and morbidity rates when compared to nonbereaved parents. Acute illnesses, hospitalizations, and medication changes are highest in the first 6 months. An understanding of bereaved parentsâ health risk indicators can help inform development of health promotion and disease prevention measures.
Methods and Analysis:
A prospective descriptive study examined 8 parent dyads. Parents completed health surveys (Patient-Reported Outcomes Measurement Information Systemâglobal, social, and sleep; Brief Symptom Inventory [BSI] 18), which are used to assess parentsâ health at 3 and 6 months after their childâs death. Demographic data included a medical history, hospital or emergency department visits, and smoking and alcohol intake. Descriptive statistics were used to compare parentsâ scores to US general population scores.
Findings:
Mothersâ and fathersâ physical, mental, and sleep health scores were typically within 1 to 2 standard deviations of the population norms. However, their social health scores were as low as 3 standard deviations and all parentsâ scores were below population norms. Four (25%) of the 16 parents had new diagnosis during the first 6 months. Based on the BSI-18, 3 parents had their scores above population cutoffs, which warranted a need for further clinical evaluation.
Conclusions:
Health data highlight the âat-riskâ health status of bereaved parents. Further validation of these data is required to support the development of health promotion and disease prevention programs
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