19,560 research outputs found
Influence of the C/O ratio on titanium and vanadium oxides in protoplanetary disks
Context. The observation of carbon-rich disks have motivated several studies
questioning the influence of the C/O ratio on their gas phase composition in
order to establish the connection between the metallicity of hot-Jupiters and
that of their parent stars.
Aims. We to propose a method that allows the characterization of the adopted
C/O ratio in protoplanetary disks independently from the determination of the
host star composition. Titanium and vanadium chemistries are investigated
because they are strong optical absorbers and also because their oxides are
known to be sensitive to the C/O ratio in some exoplanet atmospheres.
Methods. We use a commercial package based on the Gibbs energy minimization
technique to compute the titanium and vanadium equilibrium chemistries in
protoplanetary disks for C/O ratios ranging from 0.05 to 10. Our calculations
are performed for pressures ranging from 1e-6 to 1e-2 bar, and for temperatures
ranging from 50 to 2000 K.
Results. We find that the vanadium nitride/vanadium oxide and titanium
hydride/titanium oxide gas phase ratios strongly depend on the C/O ratio in the
hot parts of disks (T > 1000 K). Our calculations suggest that, in these
regions, these ratios can be used as tracers of the C/O value in protoplanetary
disks.Comment: Accepted for publication in A&
Analysis of thermal response and electrical characterisation of triple-junction solar cells based on variable solar spectral irradiance and air mass
Measuring the Awareness of University Students Towards Environmental Pollution: A Case Study of Khorfakkan University Students
The study aimed to measure the towards the environment pollution among university students, and in this a measure was prepared that contains students knowledge of environmental pollution and its effects, and students participation in facing environmental problems. The study relied on the sample social survey method by designing a sample representative of the study community consisting of 300 students at the University of Khorfakkan. A scale was designed to measure students awareness of the environment. To design the scale, a guiding program was relied upon to determine measurement criteria in modifying students behavior towards the environment. This program is composed of reinforcement strategies for self-motivation, education, change and support of positive attitudes, participation, persuasion and knowledge building. The study achieved several results, including a high rate of knowledge among university students, and students awareness of the effects of environmental pollution. On the other hand, there is a decrease in the rate of awareness of environmental issues and the rate of students participation in facing environmental problems
Improving Tenderness of Spent Layer Hens Meat Using Papaya Leaves (Carica papaya)
Two experiments were performed to study the use of papaya leaves as a meat tenderizer. The first experiment was to evaluate the effect of papaya dry leaves added to hen’s diet before slaughter. Spent hens (n=48) were used, half of them were fed a concentrate ration containing10% dried papaya leaves powder (DPLP) while others received layer ration (Control), for 10 days. The second experiment involved a comparison between papaya leaves juice (PLJ), fresh papaya leaves (FPL) and vinegar solution (VS) as marinades applied to meat for one or two hours before cooking. Spent layer hens (n=42) were used for tenderness evaluation method. After slaughtering and preparing the chickens two methods of cooking were used (oven and moist cooking). The cooked parts (breast, thigh and drumstick) were subjected to a panel test evaluation according to a designed questionnaire. Addition of dried papaya leaves powder to spent layer hens ration significantly (P≤0.05) increased the level of meat tenderness. Moist cooking had significantly (P≤0.05) improved meat tenderization compared to oven cooking. Meat treated with fresh papaya leaves had significantly (P≤0.05) improved tenderness. It was concluded that wrapping the tough meat of spent layer hens with fresh papaya leaves for one hour and moist cooking improve tenderness of meat
An Internet of Things based bed-egress alerting paradigm using wearable sensors in elderly care environment
The lack of healthcare staff and increasing proportions of elderly population is alarming. The traditional means to look after elderly has resulted in 255,000 reported falls (only within UK). This not only resulted in extensive aftercare needs and surgeries (summing up to £4.4 billion) but also in added suffering and increased mortality. In such circumstances, the technology can greatly assist by offering automated solutions for the problem at hand. The proposed work offers an Internet of things (IoT) based patient bed-exit monitoring system in clinical settings, capable of generating a timely response to alert the healthcare workers and elderly by analyzing the wireless data streams, acquired through wearable sensors. This work analyzes two different datasets obtained from divergent families of sensing technologies, i.e., smartphone-based accelerometer and radio frequency identification (RFID) based accelerometer. The findings of the proposed system show good efficacy in monitoring the bed-exit and discriminate other ambulating activities. Furthermore, the proposed work manages to keep the average end-to-end system delay (i.e., communications of sensed data to Data Sink (DS)/Control Center (CC) + machine-based feature extraction and class identification + feedback communications to a relevant healthcare worker/elderly) below 1 10 th of a second
An Upper Bound on the Higgs Boson Mass from a Positivity Condition on the Mass Matrix
We impose the condition that the eigenvalues of the mass matrix in the
shifted Lagrangian density be positive at \phi=\phi_{0}, the vacuum expectation
value of the scalar field. Using the one-loop effective potential of the
standard model, this condition leads to an upper bound on the Higgs boson mass
m_{H}: m_{H}<230GeV, for a top quark mass of 175GeV.Comment: LaTex, 5 page
Experimental investigation of modified solar still productivity under variable climatic conditions
Conversion of untreated water into drinking water using solar distillation technology can be considered as the most viable methods in the dry climate regions and remote areas. The productivity of solar stills influences by various conditions such as design, operational and environmental conditions. The current paper includes a practical investigation of the effects the climatic conditions on the fresh water production from modified single-slope solar still in Russia. Results analysis showed that the mechanism of heat transfer and mass transfer within the solar still depend on environmental parameters. The heat transfer coefficients have been gradually increased from the early morning after 08:00 am and reached the highest value at the noon then decrease gradually afternoon to reach the lowest value at 20:00 pm. The maximum value of coefficient of heat transfer by evaporation found to be 12.1 W/m2. K at 17:00 pm on 19.06.2019, then 9.9 W/m2. K at 17:00 pm on 18.06.2019, and 2 W/m2. K at 18:00 pm on 17.06.2019. Therefore, a noticeable improvement in the fresh water productivity from solar still has been observed with increasing solar radiation intensity, ambient temperature and decreasing relative humidity. The amount of production during a cloudy day was 287 ml/m2, 620 ml/m2 for a partial cloudy day and 950 ml/m2 during a sunny day. © 2020 WITPress. All rights reserved
On the truncation of the harmonic oscillator wavepacket
We present an interesting result regarding the implication of truncating the
wavepacket of the harmonic oscillator. We show that disregarding the
non-significant tails of a function which is the superposition of
eigenfunctions of the harmonic oscillator has a remarkable consequence: namely,
there exist infinitely many different superpositions giving rise to the same
function on the interval. Uniqueness, in the case of a wavepacket, is restored
by a postulate of quantum mechanics
The irreducible unitary representations of the extended Poincare group in (1+1) dimensions
We prove that the extended Poincare group in (1+1) dimensions is
non-nilpotent solvable exponential, and therefore that it belongs to type I. We
determine its first and second cohomology groups in order to work out a
classification of the two-dimensional relativistic elementary systems.
Moreover, all irreducible unitary representations of the extended Poincare
group are constructed by the orbit method. The most physically interesting
class of irreducible representations corresponds to the anomaly-free
relativistic particle in (1+1) dimensions, which cannot be fully quantized.
However, we show that the corresponding coadjoint orbit of the extended
Poincare group determines a covariant maximal polynomial quantization by
unbounded operators, which is enough to ensure that the associated quantum
dynamical problem can be consistently solved, thus providing a physical
interpretation for this particular class of representations.Comment: 12 pages, Revtex 4, letter paper; Revised version of paper published
in J. Math. Phys. 45, 1156 (2004
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