bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultrasound tomography reconstruction algorithm using two opposite rotatable linear arrays for breast cancer diagnosis
Authors: Cheng Yijun , Liu Chang , Xue Chenyang , Zhang Binzhen
Published: May 2021

This article presents a new ultrasound transmission tomography reconstruction algorithm based on a isometric fan-shaped beam along the straight trajectory for an original breast ultrasound imaging system with the cylindrical motion of opposite linear arrays. The ultrasound computed tomography system and measurement scheme are described in detail. The reconstruction algorithm is derived. The numerical breast phantom model is built, including eight structures representing the adipose tissue, glandular tissue, cysts, fibroadenomas, cancer, and calcifications. Using one array as a transmitter and the other one as a receiver, the attenuation distribution in a medium interposed between them is reconstructed. However, limited angle tomography is usually plagued by artifacts along the depth of the image that cause shape distortion to be ellipses, which had an impact on the accurate judgment of the size and shape. B-mode ultrasound images are used as prior information to aid in improving the image quality of limited aperture reconstructions. Simulation results show that the number, location, size, and shape of cancer, cyst, fibroadenoma, and calcification in the numerical breast phantom are reconstructed. Moreover, the quantitative analysis of reconstructed images demonstrates that the reconstruction performance of the region of interest has been greatly improved, which verifies the feasibility of the algorithm using two opposite linear arrays. The reconstruction images are produced by the designed ultrasound tomography reconstruction algorithm, allowing the assessment of the morphology, orientation, internal structure, and margins of lesions in the breast tissue. The ability to create good attenuation images using the cylindrical motion of opposite linear arrays allows reconstructing the three-dimensional image for breast cancer detection and characterization studies.
Enhanced pyroelectric response at morphotropic and field-induced phase transitions in ferroelectric hafnium oxide thin films
Authors: Mart Clemens , Kämpfe Thomas , Kühnel Kati , Czernohorsky Malte , Kolodinski Sabine , Wiatr Maciej , Weinreich Wenke , Eng Lukas M.
Published: May 2021

The hafnium oxide material class is characterized by the coexistence of several polymorphs between which phase transitions are induced by means of composition and external electric fields. Pyroelectric materials, which convert heat into electrical energy, exhibit the largest response at such morphotropic or field-induced phase transitions. The hafnium oxide material system is of special interest for pyroelectric applications since it allows for scalable and semiconductor-compatible fabrication. Here, we report large pyroelectric coefficients at the morphotropic transition from the ferroelectric orthorhombic to the centrosymmetric tetragonal phase. The electric field-induced transition between these two phases in doped HfO2 is found to yield large pyroelectric coefficients of up to −142 µCm−2 K−1, a value that is 20 times larger compared to AlN.
Electron beam probing of non-equilibrium carrier dynamics in 18 MeV alpha particle- and 10 MeV proton-irradiated Si-doped
β
-Ga2O3 Schottky rectifiers
Authors: Modak Sushrut , Chernyak Leonid , Schulte Alfons , Xian Minghan , Ren Fan , Pearton Stephen J. , Lubomirsky Igor , Ruzin Arie , Kosolobov Sergey S. , Drachev Vladimir P.
Published: May 2021

Minority hole diffusion length and lifetime were measured in independent experiments by electron beam-induced current and time-resolved cathodoluminescence in Si-doped β-Ga2O3 Schottky rectifiers irradiated with 18 MeV alpha particles and 10 MeV protons. Both diffusion length and lifetime exhibited a decrease with increasing temperature. The non-equilibrium minority hole mobility was calculated from the independently measured diffusion length and lifetime, indicating that the so-called hole self-trapping is most likely irrelevant in the 77–295 K temperature range.
Experimental estimation of electron–hole pair creation energy in
β
-Ga2O3
Authors: Yakimov E. B. , Polyakov A. Y. , Shchemerov I. V. , Smirnov N. B. , Vasilev A. A. , Vergeles P. S. , Yakimov E. E. , Chernykh A. V. , Ren F. , Pearton S. J.
Published: May 2021

The applicability of using Electron Beam Induced Current (EBIC) measurements on Schottky barriers to obtain the mean electron–hole pair creation energy in β-Ga2O3 is reported. It is shown that, when combined with Monte Carlo simulation, this approach yields for Si, GaN, and 4H–SiC a data set consistent with empirical expressions proposed earlier in the literature for many different semiconductors. The method is then applied to β-Ga2O3, where complications related to hole trapping in the material give rise to a strong gain in EBIC and have to be carefully treated and taken into account. When this is done, the mean electron–hole pair energy formation is found to be 15.6 eV, in reasonable agreement with the values predicted by empirical expressions.
Identification of localized radiation damage in power MOSFETs using EBIC imaging
Authors: Ashby David S. , Garland Diana , Esposito Madeline G. , Vizkelethy Gyorgy , Marinella Matthew J. , McLain Michael , Llinás J. P. , Talin A. Alec
Published: May 2021

The rapidly increasing use of electronics in high-radiation environments and the continued evolution in transistor architectures and materials demand improved methods to characterize the potential damaging effects of radiation on device performance. Here, electron-beam-induced current is used to map hot-carrier transport in model metal-oxide semiconductor field-effect transistors irradiated with a 300 KeV focused He+ beam as a localized line spanning across the gate and bulk Si. By correlating the damage to the electronic properties and combining these results with simulations, the contribution of spatially localized radiation damage on the device characteristics is obtained. This identified damage, caused by the He+ beam, is attributed to localized interfacial Pb centers and delocalized positive fixed-charges, as surmised from simulations. Comprehension of the long-term interaction and mobility of radiation-induced damage are key for future design of rad-hard devices.
Deposition of silver on the surface of microparticles of zirconium and molybdenum oxides during their synthesis by laser ablation in liquid
Authors: Malikov M.M. , Val’yano G.E. , Borodina T.I.
Published: May 2021

The deposition of silver on the surfaces of micro- and nanoparticles of zirconium, molybdenum, and their oxides, obtained by laser ablation of pure metals in aqueous solutions of silver nitrate, is investigated experimentally. Different irradiation regimes and reagent concentrations are approved. The experimental results indicate a possibility of continuous or partial coating (decorating) with silver the surfaces of nanostructures of oxides of the aforementioned metals; using such systems as substrates, one can increase the Raman scattering amplitude. Silver-coated zirconium and molybdenum oxides can be applied in the diagnostic techniques based on the phenomenon of surface-enhanced Raman scattering.
X-ray production and charged-particle acceleration in the irradiation of micro- and nanorod arrays by high-power femtosecond laser pulses
Authors: Ivanov K.A. , Mordvintsev I.M. , Kargina Yu.V. , Shulyapov S.A. , Tsymbalov I.N. , Bozhev I.V. , Volkov R.V. , Timoshenko V.Yu. , Savel’ev A.B.
Published: May 2021

The effect of the size of the rods at the structured silicon target surface on the parameters of the plasma produced when the target is exposed to a high-contrast femtosecond laser pulse with an intensity of 2 × 1018 W cm−2 is investigated. It is shown that irradiation of a target with subwavelength rods (∼ 100 nm in diameter) provides a significant (up to 250 keV) increase in the temperature of hot plasma electrons and their number in comparison with those obtained in the case of a plane target. It was found that in this case the yield of hard X-ray radiation increases several-fold. The observed effect can be attributed to increased absorption and particle motion in a complex field near plasma nonuniformities. It is shown that the presence of rods with a characteristic size of ∼ 1 μm promotes an increase in the production efficiency of multiply charged silicon ions. The result obtained is apparently associated with the radiation penetration between the rods and with collisional ionisation of particles as they fly into vacuum from deeper target layers.
Optical frequency standard with a single 171Yb+ ion
Authors: Chepurov S.V. , Pavlov N.A. , Lugovoy A.A. , Bagayev S.N. , Taichenachev A.A.
Published: May 2021

We report recent results on the development of an optical frequency standard based on the quadrupole transition in a single 171Yb+ ion. The probe laser frequency is simultaneously stabilised to the transmission peak of a Fabry – Perot reference cavity and the central resonance of the quadrupole transition of the ion with a linewidth of 30 Hz. With the experimentally obtained spectral characteristics of the probe laser and optical reference, a daily frequency stability on the order of 10−17 is demonstrated for the 171Yb+ standard.
Loss of atoms from a near-resonance hollow dipole trap
Authors: Vinogradov V.A. , Karpov K.A. , Turlapov A.V.
Published: May 2021

The lifetime of a gas of 6Li atoms in a large hollow optical dipole trap formed by radiation with a frequency detuned by 4 or 2 GHz upward from resonance is measured. The trap has the shape of a thin-walled cylinder with flat bases and a volume of ∼1 mm3. The main mechanism responsible for the loss of atoms is heating due to Rayleigh scattering. The influence of collisions of atoms with the background gas and with each other on the measured lifetime is negligible.
Generalised Ramsey methods for suppressing light shifts in atomic clocks based on the coherent population trapping effect
Authors: Kovalenko D.V. , Basalaev M.Yu. , Yudin V.I. , Zanon-Willette T. , Taichenachev A.V.
Published: May 2021

We study the possibility of suppressing light shifts in Ramsey spectroscopy of coherent population trapping (CPT) using generalised autobalanced Ramsey spectroscopy (GABRS) and combined error signal in Ramsey spectroscopy (CESRS). We consider CPT resonances excited by a coherent bichromatic field in an open Λ-system with a ‘trap’ state. Using a rigorous mathematical proof and numerical calculations, these methods are shown to lead to complete suppression of the light shift and its fluctuations. Implementation of GABRS and CESRS in CPT clocks can markedly improve accuracy and long-term stability of these devices. These methods can also be applied in atomic CPT magnetometers and interferometers.
Attractiveness, profile-picture face visibility and unprotected receptive anal intercourse in young men who have sex with men using online dating applications
Authors: Wongsomboon Val , Sietins Emils , Webster Gregory D.
Published: May 2021

Abstract Background We examined links among face visibility on dating-profile pictures, self-perceived attractiveness, condom use self-efficacy, and unprotected receptive anal intercourse (URAI) in 223 young men who have sex with men (YMSM; ages 18–24 years) using online dating applications (e.g. Grindr). Methods: Participants reported their face visibility on their main dating-profile picture, attractiveness, condom use self-efficacy, and frequency of URAI in the past 3 months. Number of casual sex partners and pre-exposure prophylaxis (PrEP) use were statistically controlled in all analyses. Results: Using a mediated moderation model, we found that a significant attractiveness-by-face-visibility interaction for URAI was fully mediated by condom use self-efficacy. Specifically, lower face visibility on profile pictures related to lower condom use self-efficacy, which in turn related to higher URAI, but only among highly attractive YMSM. Conclusions: Our findings suggest that attractive YMSM who show less-visible faces on their dating profiles could be at particularly high risk for sexually transmissible infections. This study has potentially important clinical implications because dating applications have become one of the most common ways for YMSM to find sexual partners.
Impact of an alpha helix and a cysteine–cysteine disulfide bond on the resistance of bacterial adhesion pili to stress
Authors: Baker Joseph L. , Dahlberg Tobias , Bullitt Esther , Andersson Magnus
Published: May 2021

Significance

Adhesion pili are often essential virulence factors for attachment of pathogenic bacteria in specific environmental niches. We provide mechanistic details of structural differences impacting the biophysical properties of pili found on bacteria in the urinary and intestinal tracts. First, we see that P pili from urinary tract bacteria withstand higher forces than CFA/I pili expressed on enterotoxigenic bacteria, due to a disulfide bond that limits subunit unraveling. Second, the greater elasticity of P pili is due to an

α

-helical motif that can unfold, absorbing force that could otherwise lead to bacteria detachment. Our work provides insight into the central role of pilus structural and biophysical properties for the sustained bacterial adherence necessary to initiate disease.
Associations of Alcohol, Marijuana, and Polysubstance use with Non-Adherence to COVID-19 Public Health Guidelines in a US Sample
Authors: Fendrich Michael , Becker Jessica , Park Crystal , Russell Beth , Finkelstein-Fox Lucy , Hutchison Morica
Published: May 2021

Background

We sought to understand the association between heavy alcohol and frequent drug use and non-adherence to recommended social distancing and personal hygiene guidelines for preventing the spread of COVID-19 early in the US pandemic.

Methods

A survey was offered on the crowdsourcing platform, Amazon Mechanical Turk (MTurk) during April 2020 (the early days of strict, social distancing restrictions). The study included 1,521 adults ages 18 years and older who resided in the US and were enrolled as MTurk workers, i.e., workers who are qualified by Amazon to complete a range of human interaction tasks, including surveys through the MTurk worker platform. Main predictors included measures of heavy drinking, marijuana, and polysubstance use. The dependent measures were measures of social distancing and personal hygiene, based on guidelines recommended at the time of the survey by the US Centers for Disease Control to prevent the spread of COVID-19.

Results

We found consistent negative associations between heavy drinking and drug use and adherence to social distancing and personal hygiene. Additionally, three control variables, age, gender, and race/ethnicity, were significant correlates of adherence to these measures.

Conclusions

The findings here are consistent with previous research exploring links between substance use and other adverse health behaviors. Further, the negative association between heavy drinking (five or more drinks in one sitting) and adherence underscore the public health risks entailed with the unrestricted reopening of public drinking establishments.
Exploring governance tensions of disruptive technologies: the case of care robots in Australia and New Zealand
Authors: Dickinson Helen , Smith Catherine , Carey Nicole , Carey Gemma
Published: May 2021

Robots are increasingly appearing as a potential answer to the ‘care crisis’ facing a number of countries. Although it is anticipated that many positives will flow from the application of these technologies, they are also likely to generate unexpected consequences and risks. This paper explores the use of robots within disability and aged care settings in the Australian and New Zealand contexts. Informed by thirty-five semi-structured interviews with a range of stakeholders, the paper explores why this area is so difficult to govern examining areas identified as generating tensions around the use of robots in care settings. In each of these areas some respondents saw the introduction of robots to be relatively straightforward applications that do not require extensive structures of governance. Others, however, viewed these applications as having potentially greater implications and the need to govern for these over the longer term. The three areas of tension that we explore in this paper relate to independence and surveillance, the re-shaping of human interaction and who can care. These tensions illustrate some of the problems involved in governing robots in a care service context and some of the potentially difficult issues that governments will need to resolve if these technologies are to be effective. We conclude the paper arguing what is needed is a responsive regulation approach to help resolve some of the complexities and tensions in overseeing these technologies.
Physical training considerations for optimizing performance in essential military tasks
Authors: Vaara Jani P. , Groeller Herbert , Drain Jace , Kyröläinen Heikki , Pihlainen Kai , Ojanen Tommi , Connaboy Chris , Santtila Matti , Agostinelli Philip , Nindl Brad C.
Published: May 2021

Physically demanding essential military tasks include load carriage, manual material handling and casualty evacuation. This narrative review characterizes the main physical attributes related to performance of these occupational tasks and reviews physical training intervention studies in military settings to improve performance in these military tasks. Load carriage performance requires both aerobic and neuromuscular fitness with greater emphasis on maximal strength and absolute maximal oxygen uptake, especially when carrying heavier loads. In manual material handling, maximal strength and power are strongly associated with discrete lifting, while muscular strength, muscular endurance and aerobic fitness are also associated with repetitive lifting performance. Maximal strength including grip strength, muscular endurance, absolute maximal oxygen uptake and anaerobic capacity are associated with casualty evacuation performance. The results of the present review particularly emphasize the role of muscular fitness in successful performance of the reviewed military occupational tasks. Training intervention studies indicate that load carriage performance can be effectively improved by combining strength, aerobic and specific load carriage training. Improvement in maximal lifting capacity can be achieved by strength training or combined strength and aerobic training, while strength and aerobic training alone, or their combination are effective in improving repetitive lifting, and carry tasks. Only a few studies are available for casualty evacuation and the results are inconclusive but may indicate benefits of strength or combined training. Moreover, emphasis on lower volume but higher intensity in combined training may be a feasible and effective mode to improve military occupational performance in recruits and active‐duty soldiers.
Quantification of urban greenery using hemisphere-view panoramas with a green cover index
Authors: Zhang Yonglin , Li Shanlin , Fu Xiao , Dong Rencai
Published: May 2021

Urban greenery has positive impacts on the well-being of residents and provides vital ecosystem services. A quantitative evaluation of full-view green coverage at the human scale can guide green space planning and management. We developed a still camera to collect hemisphere-view panoramas (HVPs) to obtain in situ heterogeneous scenes and established a panoramic green cover index (PGCI) model to measure human-scale green coverage. A case study was conducted in Xicheng District, Beijing, to analyze the quantitative relationships of PGCI with the normalized difference vegetation index (NDVI) and land surface temperature (LST) in different land use scenarios. The results show that the HVP is a useful quantization tool: (1) the method adaptively distinguishes the green cover characteristics of the four functional areas, and the PGCI values are ranked as follows: recreational area (29.6) > residential area (19.0) > traffic area (15.9) > commercial area (12.5); (2) PGCI strongly explains NDVI and LST, and for each unit (1%) increase in PGCI, NDVI tends to increase by 0.007, and (3) LST tends to decrease by 0.21 degrees Celsius. This research provides government managers and urban planners with tools to evaluate green coverage in complex urban environments and assistance in optimizing human-scale greenery and microclimate.
Discovery of superconductivity in AlB2-type hexagonal YGa2
Authors: Tran V H , Sahakyan M , Bukowski Z
Published: May 2021

A crystalline sample YGa2 with the AlB2-type hexagonal structure has been synthesized using the self-flux method. We measured electrical resistivity and specific heat down to 0.4 K and in fields up to 200 mT. The obtained data reveal type-II superconductivity. Unusual behaviour of the temperature dependence of upper critical field H

c2(T
c) was attributed to the crystal twinning of two phases possessing close lattice parameters. We determined thermodynamic parameters in the superconducting and normal states of YGa2. DFT calculations indicated a large change in the Fermi velocity of carriers nearby cylinder-like structured Fermi surface along the Γ − A line.
A novel deep neural network based on an unsupervised feature learning method for rotating machinery fault diagnosis
Authors: Cheng Chun , Liu Wenyi , Wang Weiping , Pecht Michael
Published: May 2021

As a simple and unsupervised feature learning method, sparse filtering has shown potential in rotating machinery fault diagnosis. However, sparse filtering has the following deficiencies: (a) the optimal sparsity of the learned features cannot be determined. (b) As a shallow network, sparse filtering has a limited capability of learning discriminative features under varying loads. (c) The diagnostic accuracy and robustness are insufficient. To overcome these deficiencies, variant sparse filtering (VSF), which can determine the optimal sparsity, is developed. Then, a deep variant sparse filtering network (DVSFN) is constructed by using stacked VSF to enhance the capability of learning discriminative features. Finally, a novel fault diagnosis method using the DVSFN is presented and verified by using rolling bearing and planetary gearbox datasets. The optimal sparsity of the learned features is determined by parametric analysis. The experimental results show that the DVSFN can adaptively learn discriminative features, irrespective of the varying loads, and the developed diagnostic method can achieve higher testing accuracy and stronger robustness in comparison to classic data-driven methods.
Possibility evaluation of the optical imaging of proton mini-beams
Authors: Yamamoto Seiichi , Yabe Takuya , Akagi Takashi
Published: May 2021

Proton therapy using mini-beams is a promising method to reduce radiation damage to normal tissue. However, distribution measurements of mini-beams are difficult due to their small structures. Since optical imaging is a possible method to measure high-resolution two-dimensional dose distribution, we conducted optical imaging of an acrylic block during the irradiation of mini-beams of protons. Mini-beams were made from a proton pencil beam irradiated to 1 mm slits made of tungsten plate. During irradiation of the mini-beams to the acrylic block, we measured the luminescence of the acrylic block using a charge-coupled device camera. With the measurements, we could obtain slit beam images that have slit shapes in the shallow area while they were uniform in their Bragg peaks, which was similar to the case of simulated optical images by Monte Carlo simulations. We confirmed that high-resolution optical imaging of mini-beams is possible and provides a promising method for efficient quality assessment of mini-beams as well as research on mini-beam therapy.
Strong coupling effects in quantum thermal transport with the reaction coordinate method
Authors: Anto-Sztrikacs Nicholas , Segal Dvira
Published: May 2021

We present a semi-analytical approach for studying quantum thermal energy transport at the nanoscale. Our method, which is based on the reaction coordinate method, reveals the role of strong system-bath coupling effects in quantum energy transport. Considering as a case study the nonequilibrium spin-boson model, a collective coordinate is extracted from each thermal environment and added into the system to construct an enlarged system (ES). After performing additional Hamiltonian’s truncation and transformation, we obtain an effective two-level system with renormalized parameters, resulting from the strong system-bath coupling. The ES is weakly coupled to its environments, thus can be simulated using a perturbative Markovian quantum master equation approach. We compare the heat current characteristics of the effective two-state model to other techniques, and demonstrate that we properly capture strong system-bath signatures such as the turnover behavior of the heat current as a function of system-bath coupling strength. We further investigate the thermal diode effect and demonstrate that strong couplings moderately improve the rectification ratio relative to the weak coupling limit. The effective Hamiltonian method that we developed here offers fundamental insight into the strong coupling behavior, and is computationally economic. Applications of the method toward studying multi-level quantum thermal machines are anticipated.
Comment on Solvable model of bound states in the continuum (BIC) in on dimension (2019, 94, 105214)
Authors: Jones H F
Published: May 2021

We elucidate the status of the special scattering states found in this paper and explore further the relationships between scattering states and bound states of different non-analytic segments (depending on ∣x∣) of the exponential potential.
Relativistic quantum dynamics of scalar particles in the rainbow formalism of gravity
Authors: Kangal E E , Salti M , Aydogdu O , Sogut K
Published: May 2021

In the present article, we investigate the Klein–Gordon equation (KGE) in a topologically trivial Gödel-type space-time in the context of rainbow gravity (RG). Exact solutions and energy spectrum of scalar particles are obtained for the considered model. Also, the same systems are studied with the existence of the Klein–Gordon oscillator (KGO) potential. Results are evaluated by considering two different rainbow functions and they are analyzed graphically. We observe that the energy spectrum of scalar particles is modified by rainbow functions compared to the solutions obtained via the ordinary general relativity (GR) theory.
Prospects of future CMB anisotropy probes for primordial black holes
Authors: Cang Junsong , Gao Yu , Ma Yin-Zhe
Published: May 2021

Cascade of particles injected as Hawking Radiation from Primordial Black Holes (PBH) can potentially change the cosmic recombination history by ionizing and heating the intergalactic medium, which results in altering the anisotropy spectra of the Cosmic Microwave Background (CMB). In this paper, we study the expected sensitivity of several future CMB experiments in constraining the abundance of PBHs distributed in 1015∼1017 g mass window according to four mass functions: the monochromatic, log-normal, power-law and critical collapse models. Our result shows that future experiments, such as CMB-S4 and PICO, can improve the current Planck bounds by about two orders of magnitude. Most regions in PBH parameter space that are allowed by current CMB data, including monochromatically distributed PBHs with mass heavier than 3.8 × 1016 g, can be tested by upcoming missions with high significance.
The Lyα forest flux correlation function: a perturbation theory perspective
Authors: Chen Shi-Fan , Vlah Zvonimir , White Martin
Published: May 2021

The Lyα forest provides one of the best means of mapping large-scale structure at high redshift, including our tightest constraint on the distance-redshift relation before cosmic noon. We describe how the large-scale correlations in the Lyα forest can be understood as an expansion in cumulants of the optical depth field, which itself can be related to the density field by a bias expansion. This provides a direct connection between the observable and the statistics of the matter fluctuations which can be computed in a systematic manner. We discuss the way in which complex, small-scale physics enters the predictions, the origin of the much-discussed velocity bias and the `renormalization' of the large-scale bias coefficients. Our calculations are within the context of perturbation theory, but we also make contact with earlier work using the peak-background split. Using the structure of the equations of motion we demonstrate, to all orders in perturbation theory, that the large-scale flux power spectrum becomes the linear spectrum times the square of a quadratic in the cosine of the angle to the line of sight. Unlike the case of galaxies, both the isotropic and anisotropic pieces receive contributions from small-scale physics.
CMB birefringence from ultralight-axion string networks
Authors: Jain Mudit , Long Andrew J. , Amin Mustafa A.
Published: May 2021

The polarization of Cosmic Microwave Background (CMB) photons is rotated as they pass through (ultralight-) axion string loops. Studying this birefringence can reveal valuable information about the axion-photon coupling and the structure of the string network. We develop an approximate analytic formalism and identify a kernel function that can be used to calculate the two-point correlation function for CMB birefringence induced by an arbitrary axion string network. Using this formalism, we evaluate the birefringence signal for some simple loop distributions (including scaling and network collapse). We find that the angular correlation function has a characteristic angular scale set by θmin, which corresponds to the angular extent of the loops at the time of recombination. This results in a peak in the birefringence power spectrum around ℓp ∼ 1/θmin. An additional scale, controlled by the axion's mass, is introduced if the network collapses before today.
Clear evidence of a clusters in the ground state of heavy nuclei
Authors: Tanaka Junki , Yang Zaihong , Typel Stefan
Published: May 2021

We obtained clear evidence of α clustering at the surface of heavy nuclei by measuring the cross sections for quasi-free α-knockout reactions along the tin isotopic chain. The α-cluster appearance at the nuclear surface could not only be a natural explanation for the α-preformation in the α-decay theory, but also provides the modification to the relation between neutron-skin thicknesses Δτηρ and a slope parameter L in the nuclear equation of state.
Study on the relative collection efficiency of large area PMTs
Authors: Ma L. , Xia J. , Qian S. , Gao F. , Huang G. , Wu Q. , Sun J. , Ren L. , Si S. , Zhu Y. , Wang Z.
Published: May 2021

The relative collection efficiency (CE) of 20-inch
Photomultiplier Tubes (PMTs) cannot be measured directly, but it can
be obtained by the quantum efficiency (QE) of the photocathode and
the relative detection efficiency (DE) of the PMTs. The measurements
of relative CE and its spherical uniformity of the 20-inch PMTs have
been introduced in this manuscript, and the difference in
performance between Microchannel-Plate PMT (MCP-PMT) and Dynode-PMT
were shown. The CE performance for 20-inch PMTs are given and the
batch test results of CE for MCP-PMTs and Dynode-PMTs are compared
at the end of this manuscript.
Sharing the seas: a review and analysis of ocean sector interactions
Authors: Crona Beatrice , Wassénius Emmy , Lillepold Kate , Watson Reg A , Selig Elizabeth R , Hicks Christina , Österblom Henrik , Folke Carl , Jouffray Jean-Baptiste , Blasiak Robert
Published: May 2021

Ocean activities are rapidly expanding as Blue Economy discussions gain traction, creating new potential synergies and conflicts between sectors. To better manage ocean sectors and their development, we need to understand how they interact and the respective outcomes of these interactions. To provide a first comprehensive picture of the situation, we review 3187 articles to map and analyze interactions between economically important ocean sectors and find 93 unique direct and 61 indirect interactions, often mediated via the ocean ecosystem. Analysis of interaction outcomes reveals that some sectors coexist synergistically (e.g. renewable energy, tourism), but many interactions are antagonistic, and negative effects on other sectors are often incurred via degradation of marine ecosystems. The analysis also shows that ocean ecosystems are fundamental for supporting many ocean sectors, yet 13 out of 14 ocean sectors have interactions resulting in unidirectional negative ecosystem impact. Fishing, drilling, and shipping are hubs in the network of ocean sector interactions, and are involved in many of the antagonistic interactions. Antagonistic interactions signal trade-offs between sectors. Qualitative analysis of the literature shows that these tradeoffs relate to the cumulative nature of many ecosystem impacts incurred by some sectors, and the differential power of ocean sectors to exert their rights or demands in the development of the ocean domain. There are also often time lags in how impacts manifest. The ocean governance landscape is not currently well-equipped to deal with the full range of trade-offs, and opportunities, likely to arise in the pursuit of a Blue Economy in a rapidly changing ocean context. Based on our analysis, we therefore propose a set principles that can begin to guide strategic decision-making, by identifying both tradeoffs and opportunities for sustainable and equitable development of ocean sectors.
Unlocking the Future of Bioenergy in Nigeria Using Genetic Modification Framework (GMF) of Switchgrass
Authors: Onovo J C , Dashe E S , Onwualu A P , Ezealigo U S , George R
Published: May 2021

The use of biofuel is gradually becoming more attractive universally as convenient substitute for fossil fuels due to the current increase in the demand for clean and renewable energy. This is because of its contribution towards lowering the dependence on crude oil, in view of the current global decline of fuel reserves. Switchgrass (Panicumvirgatum L.) has been developed into a herbaceous bioenergy crop. The processing of non-edible switchgrass biomass for fuel production will impact on rural and national development without negatively affecting food security. One of the main challenges of the production of biofuel from plant biomass is the technological impediment of breaking down plant biomass (lignin and cellulose in plant cell walls) that can be converted into biofuel. This research work will employ the use of genomic and transgenic aspects of biotechnology, such as callus induction and culture media optimization of native switchgrass, genes and constructs, cloning and sequencing, transformation and characterization analyses to invent a genetic modification framework (GMF) technology that will result in genetically modified switchgrass capable of coproducing cellulase which will culminate to drastic reduction in the cost of production of biofuel and thereby encourage its commercialization.
Politics of Energy Sustainability and Adoption of Modern Day Best Practices: Nigeria in View
Authors: Ugwu N A , Nweke C C , Eze K K , Ugwuoke N J
Published: May 2021

The study examines the problems of electricity generation; challenges encountered and proffer solutions to the epileptic electricity supply in Nigeria. The study was a descriptive survey. Three research questions and two hypotheses guided the study. The population comprised 1870 EEDC staff. A sample size of 532 was used for the study. Data were collected through questionnaires, key informant interview (KII) and analyzed using thematic analysis, mean and ANOVA. The results showed that systemic corruption, etc. were behind insufficient power generation. The study found out that policies implemented to reform power sector is faced with emerging challenges stretching from inadequate infrastructure, inconsistent government policies and huge metering gap. The study also discovered that the solutions to the erratic power supply lies strongly on the decentralization of power sector, building capacity for local manufacturing and repairs of renewable power systems. The paper recommends that government demonstrate some degree of political willingness by formulating and implementing consistent policies, reforms to attract more local and foreign investors into the power sector.
Optimization of NaOH Treatment Conditions of Baobab Pod Fibres Using Box-Behnken Method
Authors: Isah A I , Dim P E
Published: May 2021

Natural fibres are suitable materials that represent an opportunity to partially minimize on the environmental impacts by integrating them in place of synthetic fibres because of their low cost, biodegradability, low density and renewability. This work is aimed at studying the effect of chemical treatment conditions on the Mechanical properties of baobab fibres. The tensile strength and young modulus of baobab fibres were investigated. Design expert V10 software was used to analyze the experimental data. Results were processed using analysis of variance (ANOVA) technique, namely the Box-Behnken method. The effect of NaOH treatment on functional group, surface morphology and crystallinity of fibres were also investigated. The results indicated that within the limits of treatment conditions used in this study, the proposed models adequately predicted the fibre Tensile Strength and Young Modulus.
The Effect of Elaeis Guineensis Residue on CO2 and SO2 Emissions from Coal Pellets Combustion
Authors: Onochie U P , Onoroh F , Onwurah C , Ofomatah A C
Published: May 2021

The increase in emission of greenhouse gases generated by fossil fuels such as coal has informed the need for cleaner and renewable sources of energy. Therefore, in other to mitigate the negative effect of continued coal combustion, it is essential to identify more carbon neutral fuels such as biomass. Cofiring of coal with biomass is a viable option when considering the reduction of greenhouse gas emissions during the combustion of coal in coal-fired boilers. Consequently, this study was carried out to determine the effect of elaeis guineensis residue on CO2 and SO2 emissions from coal pellets during combustion. Samples of coal and elaeis guineensis residue (i.e. palm kernel shell, PKS) were collected and pulverized. Pellets were produced mechanically using optimized mixing ratios (i.e. 90%C:10%R, 80%C:20%R,70%C:30%R, 60%C:40%R and 50%C:50%R). 100%C pellet was also produced. The pellets were thereafter characterized (i.e. proximate and ultimate analyses) in accordance to ASTM Standards. From the results, quantitative analysis of optimized pellets showed that elaeis guineensis palm kernel shell has potential tendency of reducing percentage combustion CO2 and SO2 emissions from the 100%C pellets. The least optimized pellet (i.e. 90%C:10%R) has a percentage reduction of 3.01% CO2 and 42.86% SO2 on dry basis.
Modeling and Performance Assessment of 6mw Net-Metered Grid Tied Photovoltaic System for Owerri Metropolis
Authors: Okwe Gerald I , Akwukwaegbu I.O , Anyaehie M. U , Okebaram P. N , Onu P. T
Published: May 2021

The Nigerian Electricity grid is highly dominated by conventional power plants with a total installed capacity of 12,522MW. Presently, 5420.30 MW of power is being transmitted to the grid which is grossly insufficient for a country that requires about 180,000 MW to stabilize her power sector. Due to this energy crisis, the manufacturing industries are folding up, while others are relocating their production plants to more friendly havens because of the high cost of doing business in Nigeria. This constitutes a serious clog in the wheel of the economic and industrial progress of the country. This paper presents an effective alternative for the energy supply problem by adopting an unconventional PV system which operates in grid-connected mode incorporated with Net-meter to take charge of energy transaction. The system also contains a battery bank to compensate for seasonal variations. The simulation was carried out using PVsol premium software. The results obtained showed that Owerri has a good solar radiation to build PV system in large quantities, with annual yield factor of 1,098 kWh/kWp and performance ratio of 76.1% respectively. The process also stands the chance of saving about 11,688 kg/year of CO2 which would have been emitted to atmosphere by conventional power plants.
Social Media: An Adult Education Approach for Improving the Environmental Awareness of Timber Merchants in Udenu, Enugu State
Authors: Nwachukwu R U , Agboeze M U , Ugwunnadi C M , Ugwueze M O
Published: May 2021

Environmental awareness is very important for resolving the challenges facing the environment. This study assessed the extent to which social media as an adult education approach could improve the environmental awareness of timber merchants. Descriptive survey design was used for the study. The respondents of the study consist of 357 registered timber merchants in the study area. The data collected for the study was analyzed using percentage rating and mean score. A structured questionnaire was used to collect data for the study. The instrument was validated by three experts. Reliability co-efficient of 0.85 was obtained for the instrument. The findings, among others, were that, 85% of the timber merchants in Udenu, Enugu State made use of social media sites especially Facebook and Whatsapp; hence, social media provides opportunity for timber merchants to share ideas on environmental issues through online group discussions. The study concluded that social media could be used to promote environmental awareness on the dangers of negative environmental practices such as deforestation and improper dumping of wastes. These enable members of the society to conveniently participate and respond to information posted in relation to environmental issues.
Development of a Steam Powered Incubator with Solar Supported System
Authors: Rafiu Ogunyemi , Olugboji Oluwafemi , Adedipe Oyewole , Okoro Uzoma
Published: May 2021

This research work deals with the development of incubator powered by steam generated from boiled water in which the inner components and micro – controller are powered by solar system. The eggs incubator is designed to be powered by steam source of energy. The materials selected for the fabrication of the incubator were, plywood, Aluminum foil, Gas cylinder and aluminum condenser pipe. The wood was coated with aluminum foil inside in order to prevent heat loss, the six electric bulbs were introduced to complement the heat when the major source was down and three (3) D.C fans of 1.3A rating each for uniform distribution and circulating of heat. All these components were controlled by an integrated micro-controller circuit by sensing and processing the data (Temperature and Humidity). The Temperature, Humidity and egg turning mechanism were controlled and regulated by configuring micro-controller based on the operating conditions of the incubator. The performance evaluation of the designed incubating machine was tested for the period of 18-28 days. The incubating temperature range of (37-39°C) was maintained throughout the incubating period, and the relative humidity ranged from 45% to 60% was also maintained.
Lifelong Learning for Sustainable Community Development: Implication for Renewable Energy Education in Enugu State, Nigeria
Authors: Ugwuoke N J , Ozurumba I G , Obiozor E E , Osagie A O , Oyigbo D N , Okoye O E , Ugwu N A
Published: May 2021

The study investigated lifelong learning for sustainable community development: Implication for renewable energy education in Enugu State, Nigeria. Specifically, three research questions and two hypotheses guided the study. The study used descriptive survey research design. The population is made up of 3,960 respondents, comprising of 3,391 adult learners, 552 facilitators and 17 traditional rulers in Enugu State. A sample size of 607 consisting of 358 adult learners, 232 facilitators and 17 traditional rulers were used for the study. Simple random sampling was used to select adult learners and facilitators, while 17 traditional rulers were purposively selected. A structured questionnaire designed by the researchers was the instrument used for data collection. A reliability coefficient of 0.88 was established using Cronbach Alpha. Data collected were analyzed using mean and standard deviation for research questions while ANOVA was used for testing the null hypotheses at 0.05 level of significance. Results showed among others that lifelong learning gave more community members the opportunity to acquire and update themselves with the necessary skills. Analysis of variance of the responses of respondents indicated no significant difference at P > 0.05. The paper recommends among others that Government established departments, ministries, agencies and non-governmental organizations should collaborate and make provision for sufficient fund through adult and non-formal education to make learning more flexible and friendly to people who cannot fit-in into the formal system of education due to one problem or the other.
Reducing the Challenges of Environmental Sustainability through Adult Education Programmes in Udenu, Enugu State
Authors: Agboeze Matthias U , Nwachukwu Ruphina U. , Ugwueze Michael O. , Agboeze Maryrose N.
Published: May 2021

Environmental sustainability is an important component of sustainable development. This paper assessed the extent adult education programmes could help in reducing the challenges of environmental sustainability. The study is descriptive survey. Respondents for the study consist of 92 adult learners and 5 adult education facilitators in the study area. The data collected from the research objectives were analyzed using mean score. A 13 item questionnaire was used to collect data for the study. The instrument was validated by three experts. Cronbach Alpha technique was used to establish the reliability before administrating the instrument to the respondents. Reliability co-efficient of 0.81 was obtained. The findings, among others, were that, adult education programmes emphasize the need to balance development with conservation of environmental resources such as forests. Conclusively, it is evident that adult education programmes such as environmental education enhance environmental sustainability as it equips individuals in the society to effectively conserve their environmental resources for the present and future generation.
Mesh Sensitivity Assessment on 2D and 3D Elastic Finite Element Analysis on a Compact Tension Specimen Geometry Using Abaqus/CAE Software
Authors: Abdulsalam H.
Published: May 2021

Finite element analysis has been a tool mostly employed by engineers to conduct stress and strain analysis of a given specimen geometry, after which the numerical and analytical results are compared for validation. The validated results can then be used to predict the stress/strain and fracture mechanics behavior of more complicated structures/components. In this study, Abaqus/CAE software was employed to conduct 2- and 3-dimensionals (2D and 3D) elastic finite element analysis on compact tension C(T) specimen geometry, given a specimen width of 50mm, thickness of 25mm, initial crack length of 25mm and total applied load of 1000N. Comparisons of the predicted stress distributions along both X and Y directions (S11 and S22) from the 3D model and those of 2D plane stress/strain obtained from mesh sensitivity results were made. The highest maximum stress values along X and Y directions for 2D plane stress/strain were found to be 297.144Pa and 413.51Pa respectively, while the lowest maximum stress values of 121.681Pa and 166.614Pa for 2D plane stress, 118.121Pa and 165.049Pa for 2D plane strain in the X and Y directions respectively were recorded. Similarly, the highest and lowest maximum stress values for 3D plane stress along X and Y directions were 333.8588Pa and 474.417Pa, and 124.458Pa and 173.422Pa respectively. The stress values were found to increase as the mesh get finer, and also convergence start to initiate as the mesh refinement continued.