37 research outputs found
Modelling the intermixing effects in highly strained asymmetric InGaAs/GaAs quantum well
In this work, we have theoretically investigated the intermixing effect in
highly strained InGaAs/GaAs quantum well (QW) taking into
consideration the composition profile change resulting from in-situ indium
surface segregation. To study the impact of the segregation effects on the
postgrowth intermixing, one dimensional steady state Schrodinger equation and
Fick's second law of diffusion have been numerically solved by using the finite
difference methods. The impact of the In/Ga interdiffusion on the QW emission
energy is considered for different In segregation coefficients. Our results
show that the intermixed QW emission energy is strongly dependent on the
segregation effects. The interdiffusion enhanced energy shift is found to be
considerably reduced for higher segregation coefficients. This work adds a
considerable insight into the understanding and modelling of the effects of
interdiffusion in semiconductor nanostructures.Comment: 6 pages, 4 figure
Multidimensional Signals and Analytic Flexibility: Estimating Degrees of Freedom in Human-Speech Analyses
Recent empirical studies have highlighted the large degree of analytic flexibility in data analysis that can lead to substantially different conclusions based on the same data set. Thus, researchers have expressed their concerns that these researcher degrees of freedom might facilitate bias and can lead to claims that do not stand the test of time. Even greater flexibility is to be expected in fields in which the primary data lend themselves to a variety of possible operationalizations. The multidimensional, temporally extended nature of speech constitutes an ideal testing ground for assessing the variability in analytic approaches, which derives not only from aspects of statistical modeling but also from decisions regarding the quantification of the measured behavior. In this study, we gave the same speech-production data set to 46 teams of researchers and asked them to answer the same research question, resulting in substantial variability in reported effect sizes and their interpretation. Using Bayesian meta-analytic tools, we further found little to no evidence that the observed variability can be explained by analysts’ prior beliefs, expertise, or the perceived quality of their analyses. In light of this idiosyncratic variability, we recommend that researchers more transparently share details of their analysis, strengthen the link between theoretical construct and quantitative system, and calibrate their (un)certainty in their conclusions
Multidimensional signals and analytic flexibility: Estimating degrees of freedom in human speech analyses
Recent empirical studies have highlighted the large degree of analytic flexibility in data analysis which can lead to substantially different conclusions based on the same data set. Thus, researchers have expressed their concerns that these researcher degrees of freedom might facilitate bias and can lead to claims that do not stand the test of time. Even greater flexibility is to be expected in fields in which the primary data lend themselves to a variety of possible operationalizations. The multidimensional, temporally extended nature of speech constitutes an ideal testing ground for assessing the variability in analytic approaches, which derives not only from aspects of statistical modeling, but also from decisions regarding the quantification of the measured behavior. In the present study, we gave the same speech production data set to 46 teams of researchers and asked them to answer the same research question, resulting insubstantial variability in reported effect sizes and their interpretation. Using Bayesian meta-analytic tools, we further find little to no evidence that the observed variability can be explained by analysts’ prior beliefs, expertise or the perceived quality of their analyses. In light of this idiosyncratic variability, we recommend that researchers more transparently share details of their analysis, strengthen the link between theoretical construct and quantitative system and calibrate their (un)certainty in their conclusions
Effective generation lifetime depth profile in InAs quantum dots grown on InAlAs/InP(0 0 1)
International audienc
Nematicidal Activity of Stevia rebaudiana (Bertoni) Assisted by Phytochemical Analysis
To date, there has been great demand for ecofriendly nematicides with beneficial properties to the nematode hosting plants. Great efforts are made towards the chemical characterization of botanical extracts exhibiting nematicidal activity against Meloidogyne spp., but only a small percentage of these data are actually used by the chemical industry in order to develop new formulates. On the other hand, the ready to use farmer produced water extracts based on edible plants could be a sustainable and economic solution for low income countries. Herein, we evaluate the nematicidal potential of Stevia rebaudiana grown in Greece against Meloidogyne incognita and Meloidogyne javanica, two most notorious phytoparasitic nematode species causing great losses in tomato cultivation worldwide. In an effort to recycle the plant’s remnants, after leaves selection for commercial use, we use both leaves and wooden stems to test for activity. In vitro tests demonstrate significant paralysis activity of both plant parts’ water extracts against the second-stage juvenile (J2) of the parasites; while, in vivo bioassays demonstrated the substantial efficacy of leaves’ powder (95% at 1 g kg−1) followed by stems. Interestingly, the incorporation of up to 50 g powder/kg of soil is not phytotoxic, which demonstrates the ability to elevate the applied concentration of the nematicidal stevia powder under high inoculum level. Last but not least, the chemical composition analyses using cutting edge analytical methodologies, demonstrated amongst components molecules of already proven nematicidal activity, was exemplified by several flavonoids and essential oil components. Interestingly, and to our knowledge, for the flavonoids, morin and robinin, the anthocyanidin, keracyanin, and a napthalen-2-ol derivative is their first report in Stevia species
Deep level transient spectroscopy studies at low temperature of In0.52Al0.48As epilayers
International audienc
Hole emission processes from InAs quantum dots grown on p-type InAlAs/InP(0 0 1)
International audienc
Capacitance-voltage analysis of InAs quantum dots grown on InAlAs/InP(0 0 1)
International audienceThe electronic properties of InAs quantum dots (QDs) grown on InAlAs/InP(001) were studied by using capacitance-voltage (C-V) analysis and photoluminescence (PL) measurements. The level positions of electrons and holes could be studied separately by using n- and p-type InAlAs matrices, respectively. The holes are found to be more confined than electrons in these kinds of dots
Non-radiative recombination process in BGaAs/GaAs alloys: Two layer photothermal deflection model
International audienc
Capacitance–voltage profile characteristics of Schottky barrier structure with InAs quantum dots grown on InAlAs/InP(001)
International audienc