8,774 research outputs found
Daily Stress Recognition from Mobile Phone Data, Weather Conditions and Individual Traits
Research has proven that stress reduces quality of life and causes many
diseases. For this reason, several researchers devised stress detection systems
based on physiological parameters. However, these systems require that
obtrusive sensors are continuously carried by the user. In our paper, we
propose an alternative approach providing evidence that daily stress can be
reliably recognized based on behavioral metrics, derived from the user's mobile
phone activity and from additional indicators, such as the weather conditions
(data pertaining to transitory properties of the environment) and the
personality traits (data concerning permanent dispositions of individuals). Our
multifactorial statistical model, which is person-independent, obtains the
accuracy score of 72.28% for a 2-class daily stress recognition problem. The
model is efficient to implement for most of multimedia applications due to
highly reduced low-dimensional feature space (32d). Moreover, we identify and
discuss the indicators which have strong predictive power.Comment: ACM Multimedia 2014, November 3-7, 2014, Orlando, Florida, US
Toward optimal water management in Colorado's Lower Arkansas River Valley: monitoring and modeling to enhance agriculture and environment
Edition 1.0 June 2006.Includes bibliographical references (pages 42-44).For several years, Colorado State University has been documenting flow and water quality conditions in Colorado's Lower Arkansas River Valley with the goal of providing data and models that water users and managers can use to enhance both agriculture and the environment in the Valley. Extensive measurements are being made in the field, and some previously gathered data are still undergoing analysis. Models of the irrigated stream-aquifer system are under development, calibration, and refinement. Potential strategies for improving conditions in the river valley are being formulated and investigated. Small-scale pilot testing of solutions are scheduled to begin during the summer of 2006. The results presented in this technical report are published as a benchmark to document completion of the first phase of this work. They also provide broad information in support of current decision making in the river valley and hopefully will stimulate feedback and discussion. Some of the information presented here is provisional since it is still undergoing refinement and expansion.This research was partially funded by the U.S. Department of the Interior Geological Survey and Colorado Water Resources Research Institute Project on Grant Number 01HQGR0077, Project 2002CO6B and the Colorado Agricultural Experiment Station project COL00694 entitled 'Multidisciplinary Research on Salinity Issues in the Arkansas River Valley.
An in vitro study of the chondrogenic and immunomodulatory properties of mesenchymal stem cells from the osteoarthritic joint
Osteoarthritis (OA) is a debilitating joint disease characterised by pain and progressive destruction of elements such as articular cartilage. Autologous chondrocyte implantation is a cellular therapy developed to regenerate damaged cartilage and delay or negate the need for a total joint replacement. The use of mesenchymal stem cells (MSCs) provides an alternative to harvesting healthy cartilage in order to obtain chondrocytes for transplantation. In this thesis, the chondrogenic and immunomodulatory properties of human bone marrow (BM-MSCs), infrapatellar fat pad (FP-MSCs), subcutaneous fat (SCF-MSCs) and synovial fluid (SF-MSCs) derived mesenchymal stem/stomal cells were characterised to determine their suitability for cartilage repair. Synovial inflammation and the prevalence of macrophage subsets were determined in the synovium and infrapatellar fat pad from patients with and without OA.
FP-MSCs and SF-MSCs from the same donor differed with regards to in vitro proliferation and their response to a proinflammatory stimulus. None of the MSC populations examined displayed levels of chondrogenic potency that were akin to their matched chondrocyte counterparts, although BM-MSCs and FP-MSCs did show a more enhanced ability to undergo chondrogenesis than SCF-MSCs and SF-MSCs. Additionally, the expression of certain surface markers commonly associated with chondrogenic potency in chondrocytes, such as CD44, were not indicative of the chondrogenic propensity of MSCs. Analyses of the phenotype of macrophages in human synovium and FP showed a co-existence of pro- (M1) and anti-inflammatory (M2) cells in both tissues. However, cell surface markers employed in the study did not permit a clear distinction between M1 and M2 cells. Image analyses revealed that the obesity related hypertrophy observed in adipocytes from subcutaneous fat, does not occur in adipocytes in the FP. To conclude, the results presented in this thesis adds
to current knowledge of joint derived stem cells and immune cells
Selective Enzymatic Oxidation of Silanes to Silanols
Compared to the biological world's rich chemistry for functionalizing carbon, enzymatic transformations of the heavier homologue silicon are rare. We report that a wild‐type cytochrome P450 monooxygenase (P450_(BM3) from Bacillus megaterium, CYP102A1) has promiscuous activity for oxidation of hydrosilanes to give silanols. Directed evolution was applied to enhance this non‐native activity and create a highly efficient catalyst for selective silane oxidation under mild conditions with oxygen as the terminal oxidant. The evolved enzyme leaves C−H bonds present in the silane substrates untouched, and this biotransformation does not lead to disiloxane formation, a common problem in silanol syntheses. Computational studies reveal that catalysis proceeds through hydrogen atom abstraction followed by radical rebound, as observed in the native C−H hydroxylation mechanism of the P450 enzyme. This enzymatic silane oxidation extends nature's impressive catalytic repertoire
Statistical Signatures of Photon Localization
The realization that electron localization in disordered systems (Anderson
localization) is ultimately a wave phenomenon has led to the suggestion that
photons could be similarly localized by disorder. This conjecture attracted
wide interest because the differences between photons and electrons - in their
interactions, spin statistics, and methods of injection and detection - may
open a new realm of optical and microwave phenomena, and allow a detailed study
of the Anderson localization transition undisturbed by the Coulomb interaction.
To date, claims of three-dimensional photon localization have been based on
observations of the exponential decay of the electromagnetic wave as it
propagates through the disordered medium. But these reports have come under
close scrutiny because of the possibility that the decay observed may be due to
residual absorption, and because absorption itself may suppress localization.
Here we show that the extent of photon localization can be determined by a
different approach - measurement of the relative size of fluctuations of
certain transmission quantities. The variance of relative fluctuations
accurately reflects the extent of localization, even in the presence of
absorption. Using this approach, we demonstrate photon localization in both
weakly and strongly scattering quasi-one-dimensional dielectric samples and in
periodic metallic wire meshes containing metallic scatterers, while ruling it
out in three-dimensional mixtures of aluminum spheres.Comment: 5 pages, including 4 figure
Spectral and Timing Properties of IGR J17091-3624 in the Rising Hard State During its 2016 Outburst
We present a spectral and timing study of the NuSTAR and Swift observations
of the black hole candidate IGR J17091-3624 in the hard state during its
outburst in 2016. Disk reflection is detected in each of the NuSTAR spectra
taken in three epochs. Fitting with relativistic reflection models reveals that
the accretion disk is truncated during all epochs with , with the data favoring a low disk inclination of . The steepening of the continuum spectra between epochs
is accompanied by a decrease in the high energy cut-off: the electron
temperature drops from keV to keV, changing
systematically with the source flux. We detect type-C QPOs in the power spectra
with frequency varying between 0.131 Hz and 0.327 Hz. In addition, a secondary
peak is found in the power spectra centered at about 2.3 times the QPO
frequency during all three epochs. The nature of this secondary frequency is
uncertain, however a non-harmonic origin is favored. We investigate the
evolution of the timing and spectral properties during the rising phase of the
outburst and discuss their physical implications.Comment: 11 pages, 9 figures, accepted by Ap
Evolution of flow characteristics in a centrifugal compressor with an increase in operating speed
[EN] Developments in materials, manufacturing and computing methods have catalysed the generation of efficient compressor designs with higher specific power outputs. Centrifugal compressors have become pervasive in environments demanding a combination of higher power with smaller sizes such as unmanned aerial vehicles, micro gas turbines and turbochargers. These compressors are expected to perform optimally in a range of operational speeds and mass flow states with low acoustic emissions. The impact of operating speed on the flow and acoustic characteristics of a ported shroud compressor has been explored in this work. The operation of the open and blocked configurations of the compressor at the design and near surge points each of a lower and a higher speedline was numerically and experimentally investigated. Comparing the results, the model was shown to predict the operation of the compressor for both configurations at the investigated operating points satisfactorily in terms of both performance and dominant acoustic features. With an increase in the velocity and the Mach number due to increased operational speed, changes in the flow behaviour in the inducer and diffuser were observed. An increase in operational speed was shown to generally increase the overall acoustic emission of the compressor for both configurations. The number of distinct tones in the acoustic output and their magnitude were also seen to be a function of operating speed.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The project was sponsored and supported by the BorgWarner Turbo Systems and the Regional Growth Fund (RGF Grant Award 01.09.07.01/1789C).Sharma, S.; Garcia Tiscar, J.; Allport, JM.; Barrans, S.; Nickson, AK. (2021). Evolution of flow characteristics in a centrifugal compressor with an increase in operating speed. International Journal of Engine Research. 22(5):1592-1604. https://doi.org/10.1177/1468087420916606S1592160422
- …