Modeling Blood Flow in Veins of Uniform Properties (Giraffe Jugular Vein)

This paper models the giraffe’s jugular veins as a uniform collapsible tube from a rigid skull. The equations governing one-dimensional steady flow through such a tube for various conditions have been developed. The effects of inertial and inclination angles that have not been discussed previously have been included. It has been shown that different flows for a uniform tube (vein) are possible. However, this flow matches that of a jugular vein which is supercritical, and the steady solution has been given by the balance between the driving forces of gravity and the viscous resistance to the flow at the right atrium of the heart must be sub-critical for a fixed right-atrium pressure which means that an elastic jump is required to return the flow to sub-critical from the supercritical flow upstream this type of relationship gives rise to flow limitation at the same time given any right atrium fixed pressure there exists a maximum flow rate which when exceeded the boundary conditions of the flow do not hold boundary conditions at the right atrium are not satisfied hence making the steady flow impossible this mechanism of flow limitation is slightly different from the other one in that causes airways through forced expiration from the observation made it is clearly shown that there is an intravascular pressure difference with a change in height.

Probing the Progenitor of High-z Short-duration GRB 201221D and its Possible Bulk Acceleration in Prompt Emission

The growing observed evidence shows that the long-and short-duration gamma-ray bursts(GRBs) originate from massive star core-collapse and the merger of compact stars,respectively.GRB 201221 D is a short-duration GRB lasting~0.1 s without extended emission at high redshift z=1.046.By analyzing data observed with the Swift/BAT and Fermi/GBM,we find that a cutoff power-law model can adequately fit the spectrum with a soft E=113keV,and isotropic energy E=1.36× 10erg.In order to reveal the possible physical origin of GRB 201221 D,we adopted multi-wavelength criteria(e.g.,Amati relation,ε-parameter,amplitude parameter,local event rate density,luminosity function,and properties of the host galaxy),and find that most of the observations of GRB 201221 D favor a compact star merger origin.Moreover,we find that α is larger than 2+βin the prompt emission phase which suggests that the emission region is possibly undergoing acceleration during the prompt emission phase with a Poynting-flux-dominated jet.

Numerical Simulation of Water Waves’ Modulational Instability under the Effects of Wind’s Stress and Gravity Force Relaxation

The waves driven by the wind do not move on the water as ordinarily done by sailboats. Indeed, the movement of the waves driven by the wind is more complex than the sailboats’ translation movement that we know. The movement of the wave in our particular case results from the chain-job done by wind’s stress and gravity forces: material is collected upstream (erosion phenomenon) and then deposited on the wave’s summit by the wind. This material deposited on the summit of the wave by the wind is then removed and dispatched on the downstream side of the wave by gravity forces. As always happens in any chain-job: if the wind works faster than gravity forces, great accumulation of material will occur at the summit of the wave that will lead to an increase in its (the wave in this case) height. If conversely the wind works more slowly, a deficit in material delivery will occur and gravity force goes directly to remove material on the wave’s summit and lead to a decrease in its height. In terms of Mechanics, we know that the main obstacle that can seriously disturb the work of the wind is the unavailability of water or so its viscosity. Given the complexity of the process to be studied, it seemed necessary for us to make a use of modulational instability theories such as the standard NLSE in order to better understand the contribution of wind and water viscosity to modulations of driven waves’ amplitudes (or phases): modulations which sometimes can accidentally trigger unpredictable rogue waves.

Curvature, Hybridization and Contamination of Carbon Nanostructures Analysis Using Electron Microscopy and XANES Spectroscopy

The ability to control the nanoscale shape of carbon nanostructures during wide-scale synthesis process is an essential goal in research for Nanotechnology applications. This paper reports a significant progress toward that goal. Variant CVD has been used for the synthesis of the samples studied. Curvature, hybridization and contamination are analyzed using Electron Microscopies and XANES spectroscopy. The investigations of the results show that four types of samples are obtained. They are carbon nanotubes (CNTs), carbon nanofibers (CNFs), carbon nanowalls (CNWs) and carbon nanoparticles (CNPs). Almost all of them have catalyst nanoparticles (metal) on top in top growth model or on base in base growth model and encapsulated or adsorbed in sidewalls. The orientation of tubular carbon nanomaterials depends on operating parameters. They are classified in three groups: the poorly oriented, the medium oriented and the highly oriented. Their contamination (radicals, atoms and molecules) and hybridization are intrinsically related to the curvature of their graphene layers. XANES spectroscopy allows quantitative characterization of nanomaterials.

Construction of Non-Symmetric Balanced Incomplete Block Design through Combination of Symmetric Disjoint Balanced Incomplete Block Designs

The existence of several non-symmetric balanced incomplete block designs (BIBDs) is still unknown. This is because the non-existence property for non-symmetric BIBDs is still not known and also the existing construction methods have not been able to construct these designs despite their design parameters satisfying the necessary conditions for the existence of BIBD. The study aimed to bridge this gap by introducing a new class of non-symmetric BIBDs. The proposed class of BIBDs is constructed through the combination of disjoint symmetric BIBDs. The study was able to determine that the total number of disjoint symmetric BIBDs (n) with parameters (v = b, r = k, λ) that can be obtained from an un-reduced BIBD with parameters (v, k) is given by n = r - λ. When the n symmetric disjoint BIBDs are combined, then a new class of symmetric BIBDs is formed with parameters v* = v, b* = nb, r* = nr, k* = k, λ* = λ, where 2≤ n ≤ r - λ. The study established that the non-existence property of this class of BIBD was that when is not a perfect square then v should be even and when v* is odd then the equation should not have a solution in integers x, y, z which are not all simultaneously zero. In conclusion, the study showed that this construction technique can be used to construct some non-symmetric BIBDs. However, one must first construct the disjoint symmetric BIBDs before one can construct the non-symmetric BIBD. Thus, the disjoint symmetric BIBDs must exist first before the non-symmetric BIBDs exist.

Development of the N-Doped Cu-Carbon Composite as a Novel Catalyst for the Removal Reactive Black 5

In this study, two Cu-based catalysts with and without N doped carbon matrix, named N-Cu/CuO/C and Cu/CuO were synthesized via calcination of melamine-cupper acetate complex and cupper acetate at 500°C under an inert atmosphere. The catalysts were characterized by X-ray powder diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM), and CHNS elemental analyzer. The catalytic activity of both catalysts was evaluated through the NaBH4 associated reduction of commercial textile dye named reactive black 5 (RB5). The kinetics of the reduction of reactive black 5 was also described by the pseudo-first-order kinetic equation. For the studied reduction, N-Cu/CuO/C exhibited enhanced catalytic activity both in conversion and kinetics (97% conv. in 315 sec) compared to that of by Cu/CuO/C (25% conv. in 1500 sec). Besides, N-Cu/CuO/C also demonstrated good reusability up to four consecutive cycles.

Theoretical Analysis of Rayleigh Backscattering Noise in Fiber Raman Amplifiers

In this paper, a new theoretical model for Rayleigh backscattering (RB) analysis of fiber Raman amplifiers is proposed. The model includes all the interactions among the pumps, signals, and all orders of RB. The results show that the higher order RB has a negligible influence on the performance of the amplifier. The co-propagating and counterpropagating RB power of the signal grow quadratically with the net-gain of the amplifier. The signal to double Rayleigh backscattering noise ratio (OSNRDRB ) of backward-pumped FRAs is better than that of the forward-pumped ones at high net-gain level (＞ 13 dB), while at low net-gain level the OSNRDrb of the forward-pumped FRAs is slightly better than that of the backward-pumped ones.

Removal of Carbonyl-Containing Effluents by Photodegradation Using β-Carotene Embedded onto Zinc Oxide Particles

Environmental pollution especially in the form of effluent wastewater from industries has been a major challenge. Carbonyl-containing organic standards and sewage sample were effectively photo degraded. ZnO nanoparticles were prepared by emulsification of zinc-carbamate solution using 1 N NaOH and grafted chemically by Molecular Layer Doping method at 180 °C with β-carotene extracted using methanol by refluxing at 50 °C at varying concentrations. Intrinsic and grafted β-carotene ZnO were characterized using FTIR (Fourier transform infrared spectroscopy) and their spectra differed in an additional peak at around 1,435 nm corresponding to the organ metallic bond Zn-C. UV-Vis spectra of the two composites indicated a blue shift in the grafted samples. This translated to a reduced band gap from 3.5 eV to 3.4 eV. Comparison in the rates of photodegradation of pure organic compounds, organic effluents and color change of dyes was in the order 1% grafted, 0.5% grafted, intrinsic ZnO and blank sample. When 10.0 mL of sewerage water was photo degraded using both sunlight and UV-Lamp for 40 minutes, the amount of carbonyls present decreased by 28.5% for β-carotene grafted ZnO, 24.5% for intrinsic ZnO and 0.6% for a blank sample.

Theoretical Investigation of X-Ray Absorption near Edge Spectroscopy (XANES) Angular Dependence of Aligned Carbon Nanotubes Grown by DC HF CVD Process

Carbon nanotubes (CNTs) grown on plain substrates SiO2/Si(100) by a direct current and hot filaments catalytic chemical vapor deposition process have been studied by synchrotron X-ray absorption near edge spectroscopy (XANES) technique to theoretically investigate the angular-dependence of carbone (C) K-edge π* and σ* transitions. Experimental XANES spectra show that π* resonance increases with the incidence angle from normal to grazing incidence angle while σ* resonance decreases. This has been explained by the sine-square and cosine-square dependencies of π* and σ* intensities, respectively. These results were confirmed by theoretical XANES curves of highly oriented pyrolytic graphite (HOPG) and CNTs plotted versus incidence angle. It has been shown that π* and σ* transitions strongly depend on the nature of polarized light (linearly or circularly). At the linear polarized light, π* resonance is a preference as well as at right-circular polarized. At the left-circular polarized light, σ* resonance is a preference. The π* intensities are high at parallel orientation and the σ* intensities are low at normal orientation. The smallest π* intensity is noticed at normal orientation, where the π* orbitals are supposed to be lying parallel to the surface plane for perfectly aligned HOPG or CNTs. This explains the incomplete extinction of π* intensity. We noticed at parallel orientation a region where any π* and σ* transitions did not expect because of the lack of polarization light.

Effect of Head Position Angles on the Blood Flow in the Jugular Vein of Giraffes

The study investigated the effect of the angular position of the head on the blood flow in the jugular vein of giraffes. The vein considered is elastic and collapsible such that its cross-sectional area is not uniform. Transmural pressure causes the blood to move along the vein. Mathematical equations describing the flow were developed, and the vein was considered to be inclined at an angle φ to the horizontal. A finite-difference scheme was used to solve the equations of motion for the flow. The results are presented via relevant tables and plots. Our findings show that a change in the position of the head causes variation in the external pressure, which in turn causes variation in the cross-sectional area of the vein. Moreover, a drop (or increase) in the inertial pressure of the blood may cause the vein to collapse (or distend), which again triggers a change in the pressure.

Catalytic Reduction of Textile Dyes by N-Doped Ti-Melamine Capped Ag2S Nano Composites

Waste water expulsion containing toxic and hazardous ingredients from textile industry is one of the biggest concerns in this modern age. N-doped nano composites as an efficient catalyst are playing a significant role in reducing the toxicity of that textile effluent. N-doped Ti-Mel capped Ag2S NCs (N-Ti-C/Ag2S NCs) and N-doped TiO2 capped Ag2S NCs (TiO2/Ag2S NCs) were synthesized via calcinations at 700°C, whereas Ag2S NCs was prepared by simple hydrothermal treatment process at 120°C and confirmed by FTIR and SEM (EDX). N-Ti-C/Ag2S NCs were applied in presence of reducing agent NaBH4 with a green method to decolorize the textile dyes Levafix Amber RR (LA) and Remazol Blue RR (RB). Moreover, Ag2S NCs, TiO2/Ag2S NCs, NaBH4 and TiO2 were also investigated. Using UV-visible spectroscopy the progress time was measured to decolorize textile dye RB and completed within 3.15 mins, 12.15 mins, 12.15 mins for N-Ti-C/Ag2S NCs, Ag2S NCs and TiO2/Ag2S NCs respectively, while for LA the catalytic reduction taken for the same NCs was 8.15 mins, 12.15 mins and 30.15 mins respectively. N-Ti-C/Ag2S NCs based catalyst afforded excellent catalytic reduction activity in both cases. Interestingly the effect of NaBH4 itself and TiO2 in presence of NaBH4 was less than 5% after 30 mins. Finally, the reusability for Ti-Mel capped Ag2S NCs evaluated up to four cycles.

Alignment of Vertically Grown Carbon Nanostructures Studied by X-Ray Absorption Spectroscopy

X-Ray Absorption Spectroscopy (XAS) on the carbon K edge of carbon nanostructures (nanotubes, nanofibers, nanowalls) is reported here. They are grown on plain SiO2 (8 nm thick)/Si(100) substrates by a Plasma and Hot Filaments-enhanced Catalytic Chemical Vapor Deposition (PE HF CCVD) process. The morphology and the nature of these carbon nanostructures are characterized by SEM, TEM and Raman spectroscopy. According to conditions of catalyst preparation and DC HF CCVD process, carbon nanotubes (CNTs), carbon nanofibers (CNFs), carbon nanowalls (CNWs), carbon nanoparticles (CNPs) with different orientation of the graphene plans or shells can be prepared. From the angular dependence of the incident light and geometrical morphology of the nanostructures, wide variations of the C K-edge intensity of the transitions to the empty π* and σ* states occur. A full lineshape analysis of the XAS spectra has been carried out using a home-made software, allowing estimating the relative proportion of π* and σ* transitions. A geometrical model of the angular dependence with the incidence angle of the light and the morphology of the carbon nanostructures is derived. With normalization to the HOPG (Highly Oriented Pyrolytic Graphite graphite) reference case, a degree of alignment can be extracted which is representative of the localized orientation of the graphitic carbon π bonds, accounting not only for the overall orientation, but also for local defects like impurities incorporation, structural defects ... This degree of alignment shows good agreement with SEM observations. Thus CNTs films display degrees of alignment around 50%, depending on the occurrence of defects in the course of the growth, whereas no special alignment can be detected with CNFs and CNPs, and a weak one (about 20%) is detected on CNWs.

A compartmental model to investigate the dynamics of the COVID-19 pandemic:A case study in five countries

Coronavirus Disease 2019(COVID-19),caused by severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)infections,was declared a pandemic by the WHO on March 12,2020.By April 10,2020,it has spread to almost 215 UN Territories,affected more than 1,600,000 people,and become fatal to more than 100,000 people.We propose a compartmental model to investigate the dynamics of the COVID-19 pandemic and analyze the effects of governments and health officials’intervention strategies,using data in the USA,Italy,Spain,Germany,and France.These are the countries with the most confirmed cases of the COVID-19 as of April 11,2020.We perform parameter estimations,sensitivity,and predictive analysis and compare the COVID-19 trend in these understudy countries.Based on the model,we compute the basic reproduction number of the pandemic in these countries.The results indicate that the most sensitive parameters are the contact rate and degree of intervention;these parameters have high value in containing the pandemic.The basic reproduction number in each of the countries under study is more than unity.Based on our findings,the COVID-19 pandemic will continue to spread;but higher compliance with the intervention strategies will help minimize the disease’s spread.

A COVID-19 mathematical model of at-risk populations with non-pharmaceutical preventive measures:The case of Brazil and South Africa

This work examines a mathematical model of COVID-19 among two subgroups:low-risk and high-risk populations with two preventive measures;non-pharmaceutical interventions including wearing masks,maintaining social distance,and washing hands regularly by the low-risk group.In addition to the interventions mentioned above,highrisk individuals must take extra precaution measures,including telework,avoiding social gathering or public places,etc.to reduce the transmission.Those with underlying chronic diseases and the elderly(ages 60 and above)were classified as high-risk individuals and the rest as low-risk individuals.The parameter values used in this study were estimated using the available data from the Johns Hopkins University on COVID-19 for Brazil and South Africa.We evaluated the effective reproduction number for the two countries and observed how the various parameters affected the effective reproduction number.We also performed numerical simulations and analysis of the model.Susceptible and infectious populations for both low-risk and high-risk individuals were studied in detail.Results were displayed in both graphical and table forms to show the dynamics of each country being studied.We observed that non-pharmaceutical interventions by highrisk individuals significantly reduce infections among only high-risk individuals.In contrast,non-pharmaceutical interventions by low-risk individuals have a significant reduction in infections in both subgroups.Therefore,low-risk individuals’preventive actions have a considerable effect on reducing infections,even among high-risk individuals.

The impact of implementing HIV prevention policies therapy and control strategy among HIV and AIDS incidence cases in Malaysia

Malaysia is faced with a high HIV/AIDS burden that poses a public health threat.We constructed and applied a compartmental model to understand the spread and control of HIV/AIDS in Malaysia.A simple model for HIV and AIDS disease that incorporates condom and uncontaminated needle-syringes interventions and addresses the relative impact of given treatment therapy for infected HIV newborns on reducing HIV and AIDS incidence is presented.We demonstrated how treatment therapy for new-born babies and the use of condoms or uncontaminated needle-syringes impact the dynamics of HIV in Malaysia.The model was calibrated to HIV and AIDS incidence data from Malaysia from 1986 to 2011.The epidemiological parameters are estimated using Bayesian inference via Markov chain Monte Carlo simulation method.The reproduction number optimal for control of the HIV/AIDS disease obtained suggests that the disease-free equilibrium was unstable during the 25 years.However,the results indicated that the use of condoms and uncontaminated needle-syringes are pivotal intervention control strategies;a comprehensive adoption of the intervention may help stop the spread of HIV disease.Treatment therapy for newborn babies is also of high value;it reduces the epidemic peak.The combined effect of condom use or uncontaminated needle-syringe is more pronounced in controlling the spread of HIV/AIDS.

The Effect of the Width of the Incident Pulse to the Dielectric Transition Layer in the Scattering of an Electromagnetic Pulse–a Qubit Lattice Algorithm Simulation

The effect of the thickness of the dielectric boundary layer that connects amaterial of refractive index n1 to another of index n2 is considered for the propagation of an electromagnetic pulse.A qubit lattice algorithm(QLA),which consists of a specially chosen non-commuting sequence of collision and streaming operators acting on a basis set of qubits,is theoretically determined that recovers theMaxwell equations to second-order in a small parameterǫ.For very thin but continuous boundary layer the scattering properties of the pulse mimics that found from the Fresnel discontinuous jump conditions for a plane wave-except that the transmission to incident amplitudes are augmented by a factor of√n2/n1.As the boundary layer becomes thicker one finds deviations away from the discontinuous Fresnel conditions and eventually one approaches the expectedWKB limit.However there is found a small but unusual dip in part of the transmitted pulse that persists in time.Computationally,the QLA simulations still recover the solutions to Maxwell equations even when this parameterǫ→1.On examining the pulse propagation in medium n1,ǫcorresponds to the dimensionless speed of the pulse(in lattice units).

COVID-19 intervention models: An initial aggressive treatment strategy for controlling the infection

The novel coronavirus(COVID-19)outbreak emerged in December 2019.The disease has caused loss of many lives and has become an unprecedented threat to public health worldwide.We develop simple COVID-19 epidemic models to study treatment strategies to control the pandemic.The results show that eradication of the disease is possible if the efficacy of treatment is perfect.We also investigate the existence of a dual-rate effect.Conditions under which the effect occurs are derived.When the effect is present,a tactic to control the infection might be to initially treat infected individuals aggressively at a relatively high rate to drive the prevalence to a lower region that can be maintained in the long run at a relatively moderate rate and cost.

Anisotropic stars in modified gravity:An extended gravitational decoupling approach

In this study,we conduct an investigation on decoupling gravitational sources under the framework of f(R,T)gravity.Basically,the complete geometric deformation technique is employed,which facilitates finding the exact solutions to the anisotropic astrophysical system smoothly without imposing any particular ansatz for the deformation function.In addition,we used 5-dimensional Euclidean spacetime in order to describe the embedding Class Ⅰ spacetime in order to obtain a solvable spherical physical system.The resulting solutions are both physically interesting and viable with new possibilities for investigation.Notably,the present investigation demonstrates that the mixture of f(R,T)+CGD translates to a scenario beyond the pure GR realm and helps to enhance the features of the interior astrophysical aspects of compact stellar objects.To determine the physical acceptability and stability of the stellar system based on the obtained solutions,we conducted a series of physical tests that satisfied all stability criteria,including the nonsingular nature of density and pressure.