360 research outputs found
Latent profile analysis as a method for process evaluations : Discovering response subgroups in a mindfulness intervention
Rationale. Clustering techniques have been used within intervention studies to locate any distinct subgroups among intervention participants. One way in which they have not yet been utilized, but for which there is potential benefit, is in finding different motivational and behavioral response types to a newly introduced behavior. Objective This study aimed to use latent profile analyses (the same as latent class analyses except with continuous indicator variables) to identify 1) types, or classes, in terms of social cognitive responses to a mindfulness intervention, using The Reasoned Action Approach constructs, and 2) longitudinal/change trajectory classes of the target behavior (i.e., mindfulness practice). Methods The data derived from a school-based mindfulness intervention (N = 1646) among 12-15 year-olds, conducted in southern Finland from 2014 to 2016. We explored associations between the identified classes and with gender, linguocultural group, and mental health and practice outcomes. Results Analyses indicated a solution of five latent classes for both social cognition post-intervention—Uncertain but Positive (40.2%), Acceptable but No (18.8%), Indifferent (16.8), Inclined (15.5%), Disinclined (8.6%)—and practice trajectories—Stable Low (52.1%), Decreased from Seldom (25.8%), Decreased from Sometimes (10.7%), Increased from Zero (6.8%), Increased from Seldom (4.6%). The strongest differentiating theoretical construct among the social cognitive classes was a descriptive norm. The classes were characterized by some associations between each other (e.g., “Acceptable but No” and “Stable Low”) and with linguocultural groups (e.g., “Inclined” and small language minorities) and mental health (e.g., “Disinclined” and externalization and depressive symptoms), but no specific associations were found by gender. Conclusions This study shows how more person-centered analyses can be utilized in process evaluations, which predominantly only make use of variable-centered analyses. This knowledge could suggest ways to tailor universal interventions for subgroups with different receipt profiles and thereby improve intervention acceptability and engagement.Peer reviewe
From Extractivism to Global Extractivism : The Evolution of an Organizing Concept
All the named authors were members of the Helsinki Research Working Group on Global Extractivisms and Alternatives, who jointly constructed this article. Equal authorship by all authors is recognised.Research on extractivism has rapidly proliferated, expanding into new empirical and conceptual spaces. We examine the origins, evolution, and conceptual expansion of the concept. Extractivism is useful to analyze resource extraction practices around the world. ‘Global Extractivism’ is a new conceptual tool for assessing global phenomena. We situate extractivism within an ensemble of concepts, and explore its relation to development, the state, and value. Extractivism as an organizing concept addresses many fields of research. Extractivism forms a complex of self-reinforcing practices, mentalities, and power differentials underwriting and rationalizing socio-ecologically destructive modes of organizing life-through subjugation, depletion, and non-reciprocity.Peer reviewe
Vertical-external-cavity surface-emitting lasers and quantum dot lasers
The use of cavity to manipulate photon emission of quantum dots (QDs) has
been opening unprecedented opportunities for realizing quantum functional
nanophotonic devices and also quantum information devices. In particular, in
the field of semiconductor lasers, QDs were introduced as a superior
alternative to quantum wells to suppress the temperature dependence of the
threshold current in vertical-external-cavity surface-emitting lasers
(VECSELs). In this work, a review of properties and development of
semiconductor VECSEL devices and QD laser devices is given. Based on the
features of VECSEL devices, the main emphasis is put on the recent development
of technological approach on semiconductor QD VECSELs. Then, from the viewpoint
of both single QD nanolaser and cavity quantum electrodynamics (QED), a
single-QD-cavity system resulting from the strong coupling of QD cavity is
presented. A difference of this review from the other existing works on
semiconductor VECSEL devices is that we will cover both the fundamental aspects
and technological approaches of QD VECSEL devices. And lastly, the presented
review here has provided a deep insight into useful guideline for the
development of QD VECSEL technology and future quantum functional nanophotonic
devices and monolithic photonic integrated circuits (MPhICs).Comment: 21 pages, 4 figures. arXiv admin note: text overlap with
arXiv:0904.369
Ni+-irradiated InGaAs/GaAs quantum wells: picosecond carrier dynamics
Room-temperature carrier dynamics as functions of heavy-ion implantation and subsequent thermal annealing were investigated for technologically important InGaAs/GaAs quantum wells (QWs) by means of a time-resolved up-conversion method. Sub-picosecond lifetimes were achieved at 10 MeV Ni+ doses of (20-50) x 1010 ions cm-2. The decay rates reached a maximum at the highest irradiation dose, yielding the shortest lifetime of the confined QW states of 600 fs. A simple theoretical model is proposed for the photodynamics of the carriers. The relaxation rate depended on the irradiation dose according to a power law of 1.2, while the irradiated and subsequently annealed samples exhibited a power law of 0.35. The results are qualitatively interpreted.Room-temperature carrier dynamics as functions of heavy-ion implantation and subsequent thermal annealing were investigated for technologically important InGaAs/GaAs quantum wells (QWs) by means of a time-resolved up-conversion method. Sub-picosecond lifetimes were achieved at 10 MeV Ni+ doses of (20-50) x 1010 ions cm-2. The decay rates reached a maximum at the highest irradiation dose, yielding the shortest lifetime of the confined QW states of 600 fs. A simple theoretical model is proposed for the photodynamics of the carriers. The relaxation rate depended on the irradiation dose according to a power law of 1.2, while the irradiated and subsequently annealed samples exhibited a power law of 0.35. The results are qualitatively interpreted.Room-temperature carrier dynamics as functions of heavy-ion implantation and subsequent thermal annealing were investigated for technologically important InGaAs/GaAs quantum wells (QWs) by means of a time-resolved up-conversion method. Sub-picosecond lifetimes were achieved at 10 MeV Ni+ doses of (20-50) x 1010 ions cm-2. The decay rates reached a maximum at the highest irradiation dose, yielding the shortest lifetime of the confined QW states of 600 fs. A simple theoretical model is proposed for the photodynamics of the carriers. The relaxation rate depended on the irradiation dose according to a power law of 1.2, while the irradiated and subsequently annealed samples exhibited a power law of 0.35. The results are qualitatively interpreted.Peer reviewe
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