590 research outputs found
A High Speed Particle Phase Discriminator (PPD-HS) for the classification of airborne particles, as tested in a continuous flow diffusion chamber
© Author(s) 2019. This work is distributed under the Creative Commons Attribution 4.0 License.A new instrument, the High-speed Particle Phase Discriminator (PPD-HS), developed at the University of Hertfordshire, for sizing individual cloud hydrometeors and determining their phase is described herein. PPD-HS performs an in situ analysis of the spatial intensity distribution of near-forward scattered light for individual hydrometeors yielding shape properties. Discrimination of spherical and aspherical particles is based on an analysis of the symmetry of the recorded scattering patterns. Scattering patterns are collected onto two linear detector arrays, reducing the complete 2-D scattering pattern to scattered light intensities captured onto two linear, one-dimensional strips of light sensitive pixels. Using this reduced scattering information, we calculate symmetry indicators that are used for particle shape and ultimately phase analysis. This reduction of information allows for detection rates of a few hundred particles per second. Here, we present a comprehensive analysis of instrument performance using both spherical and aspherical particles generated in a well-controlled laboratory setting using a vibrating orifice aerosol generator (VOAG) and covering a size range of approximately 3-32 ÎŒm. We use supervised machine learning to train a random forest model on the VOAG data sets that can be used to classify any particles detected by PPD-HS. Classification results show that the PPD-HS can successfully discriminate between spherical and aspherical particles, with misclassification below 5% for diameters >3ÎŒm. This phase discrimination method is subsequently applied to classify simulated cloud particles produced in a continuous flow diffusion chamber setup. We report observations of small, near-spherical ice crystals at early stages of the ice nucleation experiments, where shape analysis fails to correctly determine the particle phase. Nevertheless, in the case of simultaneous presence of cloud droplets and ice crystals, the introduced particle shape indicators allow for a clear distinction between these two classes, independent of optical particle size. From our laboratory experiments we conclude that PPD-HS constitutes a powerful new instrument to size and discriminate the phase of cloud hydrometeors. The working principle of PPD-HS forms a basis for future instruments to study microphysical properties of atmospheric mixed-phase clouds that represent a major source of uncertainty in aerosol-indirect effect for future climate projections..Peer reviewe
Perceptions of patients regarding quality nursing care (QNC) at a tertiary hospital in Karachi, Pakistan
Background: Patientsâ experiences regarding the quality of care continue to be a hot topic of discussion in the healthcare industry. Exploring the quality of nursing care from the patientsâ perspectives is a vital element of quality evaluation. The purpose of this study was to explore the patientsâ perspectives regarding quality nursing care.
Methodology: A qualitative descriptive exploratory design was used. A total of twelve participants were recruited from one medical and one surgical unit at a tertiary care hospital in Karachi, Pakistan. Purposive sampling was used to select the participants. Data was collected through semi-structured interviews. A thematic analysis approach was used for data analysis.
Results: Data analysis generated three main themes: (1) meaning of QNC, (2) characteristics of nurses, and (3) participantsâ recommendations.
Conclusion: Nursing care continues to be the foundation of healthcare and QNC could have a great effect on patientsâ positive outcome of recovery and well- being. The study also provided vital implications for nursing administrators, practicing nurses, nursing, education, and research
The Effects of Equine-Assisted Therapy on Gait in Adults with Parkinsonâs Disease: A Preliminary Analysis
Parkinsonâs disease (PD) is a chronic, progressive, neurological disorder caused by the destruction of dopamine-producing neurons in the substantia nigra of the brain. To treat motor symptoms of PD, individuals may choose alternative modes of exercise, such as equine-assisted therapy (EAT), to improve physiological health. PURPOSE: To determine changes in gait following 8 weeks of Equine Assisted Therapy (EAT) in older men with PD. METHODS: Six older adults (age = 68.0 ± 8.6 yrs; height = 178.6 ± 8.3 cm; weight = 93.4 ± 16.3 kg; Hoehn and Yahr classification = 2.8 ± 0.4; time since diagnosis = 7.3 ± 5.0 yrs) performed two, 60-minute riding sessions weekly for 8 weeks. Before, midway, immediately after, and at two points following the EAT program (at 8 weeks and 16 weeks), spatiotemporal parameters of gait were measured using motion capture with infrared markers strategically placed on lower-body anatomical landmarks. Participants walked at a self-selected speed without the use of an assistive device in the capture space for 15 consecutive strides, turned around, and walked back across the space. Gait velocity, step length, time spent in stance phase, time spent in swing phase, toe clearance were collected. Data were analyzed using a repeated-measures analysis-of-variance and a Bonferroni correction with a significance level of 0.05. RESULTS: Gait velocity (101.8 ± 29.1 vs. 109.2 ± 34.9 vs. 116.3 ± 32.8 vs. 105.7 ± 26.2 vs. 108.0 ± 25.4 cm/s for pre-EAT, midway through EAT, immediately post-EAT, 8 weeks after EAT concluded, and 16 weeks after EAT concluded, respectively) was significant across all time points (p = 0.03). All other variables were statistically similar (p \u3e 0.05) across all time points. CONCLUSION: There is an observable trend towards significance in each gait variable immediately after 8 weeks of EAT. The study is ongoing and will further explore these differences
Remarks on flavor-neutrino propagators and oscillation formulae
We examine the general structure of the formulae of neutrino oscillations
proposed by Blasone and Vitiello(BV). Reconstructing their formulae with the
retarded propagators of the flavor neutrino fields for the case of many
flavors, we can get easily the formulae which satisfy the suitable boundary
conditions and are independent of arbitrary mass parameters ,
as is obtained by BV for the case of two flavors. In this two flavor case, our
formulae reduce to those obtained by BV under -invariance condition.
Furthermore, the reconstructed probabilities are shown to coincide with those
derived with recourse to the mass Hilbert space which is
unitarily inequivalent to the flavor Hilbert space . Such a
situation is not found in the corresponding construction a la BV. Then the new
factors in the BV's formulae, which modify the usual oscill ation formulae, are
not the trace of the flavor Hilbert space construction, but come from
Bogolyubov transformation among the operators of spin-1/2 ne utrino with
different masses.Comment: revtex, 16 page
A laboratory investigation of the ice nucleation efficiency of three types of mineral and soil dust
Surface-collected dust from three different locations around the world was
examined with respect to its ice nucleation activity (INA) with the ETH
Portable Ice Nucleation Chamber (PINC). Ice nucleation experiments were conducted with particles of 200
and 400 nm in diameter in the temperature range of 233â243 K in both the
deposition nucleation and condensation freezing regimes. Several treatments
were performed in order to investigate the effect of mineralogical
composition, as well as the presence of biological and proteinaceous, organic
and soluble compounds on the INA of mineral and soil dust. The INA of
untreated dust particles correlated well with the total feldspar and
K-feldspar content, corroborating previously published results. The removal
of heat-sensitive proteinaceous and organic components from the particle
surface with heat decreased the INA of dusts. However, the decrease in the
INA was not proportional to the amount of these organic components,
indicating that different proteinaceous and organic species have different
ice nucleation activities, and the exact speciation is required in order to
determine why dusts respond differently to the heating process. The INA of
certain dusts increased after the removal of soluble material from the
particle surface, demonstrating the low INA of the soluble compounds and/or
the exposition of the underlying active sites. Similar to the proteinaceous
organic compounds, soluble compounds seem to have different effects on the
INA of surface-collected dusts, and a general conclusion about how the
presence of soluble material on the particle surface affects its INA is not
possible. The investigation of the heated and washed dusts revealed that
mineralogy alone is not able to fully explain the observed INA of
surface-collected dusts at the examined temperature and relative humidity
conditions. The results showed that it is not possible to predict the INA of
surface-collected soil dust based on the presence and amount of certain
minerals or any particular class of compounds, such as soluble or
proteinaceous/organic compounds. Instead, at temperatures of 238â243 K the
INA of the untreated, surface-collected soil dust in the condensation
freezing mode can be roughly approximated by one of the existing surrogates
for atmospheric mineral dust, such as illite NX. Uncertainties associated
with mechanical damage and possible changes to the mineralogy during
treatments, as well as with the BET surface area and its immediate impact on
the number of active sites (ns,âBET), are addressed.</p
Heterogeneous ice nucleation properties of natural desert dust particles coated with a surrogate of secondary organic aerosol
Ice nucleation abilities of surface collected mineral dust particles from the
Sahara (SD) and Asia (AD) are investigated for the temperature (T) range
253â233 K and for supersaturated relative humidity (RH) conditions in the
immersion freezing regime. The dust particles were also coated with a proxy
of secondary organic aerosol (SOA) from the dark ozonolysis of
α-pinene to better understand the influence of atmospheric coatings on
the immersion freezing ability of mineral dust particles. The measurements
are conducted on polydisperse particles in the size range
0.01â3 ”m with three different ice nucleation chambers. Two of the
chambers follow the continuous flow diffusion chamber (CFDC) principle
(Portable Ice Nucleation Chamber, PINC) and the Colorado State University
CFDC (CSU-CFDC), whereas the third was the Aerosol Interactions and Dynamics
in the Atmosphere (AIDA) cloud expansion chamber. From observed activated
fractions (AFs) and ice nucleation active site (INAS)
densities, it is concluded within experimental uncertainties that
there is no significant difference between the ice nucleation ability of the
particular SD and AD samples examined. A small bias towards higher
INAS densities for uncoated versus SOA-coated dusts is found but
this is well within the 1Ï (66 % prediction bands) region of the
average fit to the data, which captures 75 % of the INAS densities observed in this study. Furthermore, no systematic differences are
observed between SOA-coated and uncoated dusts in both SD and AD cases,
regardless of coating thickness (3â60 nm). The results suggest that any
differences observed are within the uncertainty of the measurements or
differences in cloud chamber parameters such as size fraction of particles
sampled, and residence time, as well as assumptions in using INAS densities to compare polydisperse aerosol measurements which may show
variable composition with particle size. Coatings with similar properties to
that of the SOA in this work and with coating thickness up to 60 nm are not
expected to impede or enhance the immersion mode ice nucleation ability of
mineral dust particles.</p
Advancing Team Cohesion: Using an Escape Room as a Novel Approach
Objective: An escape room was used to study teamwork and its determinants, which have been found to relate to the quality and safety of patient care delivery. This pilot study aimed to explore the value of an escape room as a mechanism for improving cohesion among interdisciplinary healthcare teams. Methods: This research was conducted at a nonprofit medical center in Southern California. All participants who work on a team were invited to participate. Authors employed an interrupted within-subjects design, with two pre- and post- escape room questionnaires related to two facets of group cohesion: (belonging â (PGC-B) and morale (PGC-M)). Participants rated their perceptions of group cohesion before, after, and one-month after the escape room. The main outcome measures included PGC-B/M. Results: Sixty-two teams participated (n 280 participants) of which 31 teams (50%) successfully âescapedâ in the allotted 45 minutes. There was a statistically significant difference in PGC between the three time periods, F(4, 254) 24.10, p \u3c .001; Wilksâ K .725; partial g2 .275. Results indicated significantly higher scores for PGC immediately after the escape room and at the one-month follow-up compared to baseline. Conclusions: This work offers insights into the utility of using an escape room as a team building intervention in interprofessional healthcare teams. Considering the modifiability of escape rooms, they may function as valuable team building mechanisms in healthcare. More work is needed to determine how escape rooms compare to more traditional team building curriculums
Energetic outer radiation belt electron precipitation during recurrent solar activity
Transmissions from three U.S. VLF (very low frequency) transmitters were received at Churchill, Canada, during an event study in May to November, 2007. This period spans four cycles of recurrent geomagnetic activity spaced similar to 27 days apart, with daily Sigma Kp reaching similar to 30 at the peaks of the disturbances. The difference in the amplitude of the signals received during the day and during the night varied systematically with geomagnetic activity, and was used here as a proxy for ionization changes caused by energetic electron precipitation. For the most intense of the recurrent geomagnetic storms there was evidence of electron precipitation from 3 300 keV and similar to 1 MeV trapped electrons, and also consistent with the daily average ULF (ultralow frequency) Pc1-2 power (L = 3.9) from Lucky Lake, Canada, which was elevated during the similar to 1 MeV electron precipitation period. This suggests that Pc1-2 waves may play a role in outer radiation belt loss processes during this interval. We show that the > 300 keV trapped electron flux from POES is a reasonable proxy for electron precipitation during recurrent high-speed solar wind streams, although it did not describe all of the variability that occurred. While energetic electron precipitation can be described through a proxy such as Kp or Dst, careful incorporation of time delays for different electron energies must be included. Dst was found to be the most accurate proxy for electron precipitation during the weak recurrent-activity period studied
Kinetika Adsorpsi pada Penjerapan Ion Timbal Pb2+ Terlarut dalam Air Menggunakan Partikel Tricalcium Phosphate
One of the heavy metals can pollute the water is metal ion of Pb2+. Concentration of ions Pb2+ can be removed by adsorption method. The purposes of tihis research are to observe the effect of temperature and adsorbent dosage on the adsorption of metal ion Pb2+ using tricalcium phosphate (TCP) adsorben and determine a suitable adsorption kinetic model. Five hundred mililiter Pb2+ solution with of 3mg/L were added 0,5 gr, 1 gr and 1,5 gr of TCP in a glass beaker and stirred with rate of 300 rpm at a temperature of 30 oC. Pb solution was taken at a certain time, the solution centrifuged and supernatant analyzed by AAS. The result Showed that rate of adsorption increased with temperature and adsorbent dosage. Minimum constant value of adsorption kinetic of adsorption kinetic was 1,720 g/mg.min obtained at temperature 30oC and adsorbent dosage 0,5 gr. Where as maximun value adsorption kinetic constant 8,479 g/mg.min obtained at temperature 30oC adsorbent dosage 1,5 gr. The appropiate model for kinetic followed pseudo second order
The analytic hierarchy process to support decision-making processes in infrastructure projects with social impact
There is an increasing awareness among all kinds of organisations (in business,government and civil society) about the beneïŹts of jointly working with stakeholders
to satisfy both their goals and the social demands placed upon them. This is particularly the case within corporate social responsibility (CSR) frameworks. In this regard, multi-criteria tools for decision-making like the analytic hierarchy process (AHP) described in the paper can be useful for the building relationships with stakeholders. Since these tools can reveal decision-makerâs preferences, the
integration of opinions from various stakeholders in the decision-making process may result in better and more innovative solutions with signiïŹcant shared value.
This paper is based on ongoing research to assess the feasibility of an AHP-based model to support CSR decisions in large infrastructure projects carried out by Red
Electrica de España, the sole transmission agent and operator of the Spanishelectricity system
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