The Impact of E-Commerce on the Performance of Logistic Service Providers in Ghana

Since the introduction of information technology in the late 90’s, e-commerce and logistics have gained weight throughout the world. Ghana has experienced the arithmetic growth of e-commerce since the 21st century. Although, majority of Third-Party Logistic companies are from Europe and USA (FedEx, DHL, UPS, etc), there have been the introduction and development of some local 3PL (OMA Ghana Ltd, McDan Shipping, etc.). The research’s had the main objectives were to: (1) explore the inventory management model practiced by the e-commerce companies in Ghana; and (2) assess the impact of e-commerce on the performance of logistic service providers in Ghana. The study concluded that: Almost 85% of e-commerce companies in Ghana preferred Jointly Managed Model. Also, there was positive correlation between e-commerce and the performance of logistic service providers in Ghana.  The study further recommended that; the Government of Ghana should help in providing credible housing addressing system to enhance local home-to-home delivery of goods and services; and the e-commerce companies should work hand in hand to enable online payment system on their platform by providing SSL securities and Data Protection services. Keywords: E-commerce, Logistics service providers, E-commerce in Ghana. DOI: 10.7176/JESD/11-10-04 Publication date:May 31st 202

Narrowly-Banded Spectra with Peak Frequency Around 1 GHz of FRB 20201124A: Implications for Energy Function and Radiation Physics

The radiation physics of fast radio bursts (FRBs) remains an open question. Current observations have discovered that narrowly-banded bursts of FRB 20201124A are active in 0.4-2 GHz and their spectral peak frequency ($\nu^{\rm obs}_{p}$) are mostly toward $\sim 1$ GHz. Utilizing a sample of 1268 bursts of FRB 20201124A detected with the FAST telescope, we show that the $1\sigma$ spectral regime of 71.4\% events (in-band bursts) is within the FAST bandpass. Their intrinsic burst energies ($E^{\rm obs}_{\rm BWe}$) and spectral widths ($\sigma_s^{\rm obs}$) are well measured by fitting the spectral profile with a Gaussian function. The derived $E^{\rm obs}_{\rm BWe}$ and $\sigma_s^{\rm obs}$ distributions are log-normal and centering at $\log E^{\rm obs}_{\rm BWe}/{\rm erg}=37.2~ (\sigma=0.76)$ and $\log \sigma_s^{\rm obs}/{\rm GHz}=-1.16~ (\sigma=0.17)$. Our Monte Carlo simulation analysis infers its intrinsic $\nu_p$ distribution as a normal function centered at $\nu_{p,c}=1.16$ GHz ($\sigma=0.22$) and its intrinsic energy function as $\Phi(E)\propto E^{-0.60}e^{-E/E_c}$ with $E_c=9.49 \times 10^{37}$ erg. We compare these results with that of typical repeating FRBs 20121102A and 20190520B that are active over a broad frequency range at several specific frequencies and discuss possible observational biases on the estimation of the event rate and energy function. Based on these results, we argue that FRB 20201124A likely occurs in a fine-tuned plasma for maser radiations at a narrow frequency range, while FRB 20121102A and FRB 20190520B could involve clumpy plasma conditions that make maser emission around several specific frequencies in a broad range.Comment: 21 pages, 9 figures. Accepted for publication in The Astrophysical Journa

SDSS J163459.82+204936.0: A Ringed Infrared-Luminous Quasar with Outflows in both Absorption and Emission Lines

SDSS J1634+2049 is a local (z = 0.1293) infrared-luminous quasar with LIR= 10^11.91 Lsun. We present a detailed multiwavelength study of both the host galaxy and the nucleus. The host galaxy demonstrates violent, obscured star formation activities with SFR ~ 140 Msun yr^-1, estimated from either the PAH emission or IR luminosity. The optical to NIR spectra exhibit a blueshifted narrow cuspy component in Hb, HeI5876,10830 and other emission lines consistently with an offset velocity of ~900 km/s, as well as additional blueshifting phenomena in high-ionization lines , while there exist blueshifted broad absorption lines (BALs) in NaID and HeI*3889,10830, indicative of the AGN outflows producing BALs and emission lines. Constrained mutually by the several BALs with CLOUDY, the physical properties of the absorption-line outflow are derived as follows: 10^4 < n_H <= 10^5 cm^-3, 10^-1.3 <= U <= 10^-0.7 and 10^22.5<= N_H <= 10^22.9 cm^-2 , similar to those derived for the emission-line outflows. The similarity suggests a common origin. Taking advantages of both the absorption lines and outflowing emission lines, we find that the outflow gas is located at a distance of 48 - 65 pc from the nucleus, and that the kinetic luminosity of the outflow is 10^44-10^46 erg s^-1. J1634+2049 has a off-centered galactic ring on the scale of ~ 30 kpc that is proved to be formed by a recent head-on collision by a nearby galaxy. Thus this quasar is a valuable object in the transitional phase emerging out of dust enshrouding as depicted by the co-evolution scenario.Comment: 13 figures, 6 tables; accepted for publication in Ap

A Channel to Form Fast-spinning Black Hole-Neutron Star Binary Mergers as Multimessenger Sources. II. Accretion-induced Spin-up

In this work, we investigate an alternative channel for the formation of fast-spinning black hole-neutron star (BHNS) binaries, in which super-Eddington accretion is expected to occur in accreting BHs during the stable mass transfer phase within BH-stripped helium (BH--He-rich) star binary systems. We evolve intensive \texttt{MESA} grids of close-orbit BH--He-rich star systems to systematically explore the projected aligned spins of BHs in BHNS binaries, as well as the impact of different accretion limits on the tidal disruption probability and electromagnetic (EM) signature of BHNS mergers. Most of the BHs in BHNS mergers cannot be effectively spun up through accretion, if the accretion rate is limited to $\lesssim10\,\dot{M}_{\rm Edd}$, where $\dot{M}_{\rm Edd}$ is the standard Eddington accretion limit. In order to reach high spins (e.g., $\chi_{\rm BH} \gtrsim 0.5$), the BHs are required to be born less massive (e.g., $\lesssim3.0\,M_\odot$) in binary systems with initial periods of $\lesssim0.2-0.3\,{\rm days}$ and accrete material at $\sim100\,\dot{M}_{\rm Edd}$. However, even under this high accretion limit, $\gtrsim6\,M_\odot$ BHs are typically challenging to significantly spin up and generate detectable associated EM signals. Our population simulations suggest that different accretion limits have a slight impact on the ratio of tidal disruption events. However, as the accretion limit increases, the EM counterparts from the cosmological BHNS population can become bright overall.Comment: 18 pages, 9 figures, 1 table, accepted for publication in Ap

Occurrence of multi-mycotoxin in paddy rice in Guangdong Province

Objective To understand the contamination pattern of mycotoxin in paddy rice in the main rice-growing regions of Guangdong Province, and analyze the distribution difference of mycotoxin in different areas, so as to provide basis for the implementation of precise prevention and control measures. Methods A total of 120 paddy rice samples were collected from eight cities in the Pearl River Delta, northern, eastern and western Guangdong during 2018 and 2019, and were analyzed for 16 mycotoxins by multiple reaction monitoring mode of ultra performance liquid chromatography-tandem mass spectrometer. Results Among the 120 paddy rice samples, 19.17% (23/120) were positive for mycotoxins, and the main polluants were aflatoxins and fumonisins. FB1 were detected in 9.17% (11/120) of the samples, followed by 8.33% (10/120) for AFB1. Two samples had the AFB1 concentrations above the tolerance limit of 10 μg/kg. The detection values were 73.90 and 18.80 μg/kg, respectively. Among 6 trichothecene mycotoxins, only deoxynivalenol (1.67%, 2/120) and its acetyl derivatives[0.83% (1/120) for 3-Ac-DON and 0.83% (1/120) for 15-Ac-DON] were found. ZEN was found in 3.33% (4/120) of the samples. Additionally, 1.67% (2/120) of the paddy rice samples were positive for sterigmatocystin. The ochratoxin A, nivalenol, T-2 and HT-2 mycotoxins were not found in the paddy rice samples. The co-occurrence of two or more mycotoxins was confirmed in 8.33% (10/120) of the paddy rice samples, mainly combination was AFB1 and other mycotoxins. The contamination patterns were different in the eight cities. The paddy rice samples from Zhanjiang was mainly contaminated by FB1, FB2, DON and 3-Ac-DON. Samples from Heyuan were mainly contaminated by AFB1, AFB2, sterigmatocystin, FB1 and FB2. The concentration levels of ZEN, DON and 3-Ac-DON were relatively higher in samples from Shaoguan. Conclusion The paddy rice samples from Guangdong Province were contaminated by multiple mycotoxins, and the pollution patterns were different in different areas. In terms of the co-occurence of mycotoxins, some measures should be conducted to assess the exposure risk, reduce the damage, and protect the consumers food safety

Development of a prediction model to identify undiagnosed chronic obstructive pulmonary disease patients in primary care settings in China

Background: At present, a large number of chronic obstructive pulmonary disease (COPD) patients are undiagnosed in China. Thus, this study aimed to develop a simple prediction model as a screening tool to identify patients at risk for COPD. Methods: The study was based on the data of 22,943 subjects aged 30 to 79 years and enrolled in the second resurvey of China Kadoorie Biobank during 2012 and 2013 in China. We stepwisely selected the predictors using logistic regression model. Then we tested the model validity through P–P graph, area under the receiver operating characteristic curve (AUROC), ten-fold cross validation and an external validation in a sample of 3492 individuals from the Enjoying Breathing Program in China. Results: The final prediction model involved 14 independent variables, including age, sex, location (urban/rural), region, educational background, smoking status, smoking amount (pack-years), years of exposure to air pollution by cooking fuel, family history of COPD, history of tuberculosis, body mass index, shortness of breath, sputum and wheeze. The model showed an area under curve (AUC) of 0.72 (95% confidence interval [CI]: 0.72–0.73) for detecting undiagnosed COPD patients, with the cutoff of predicted probability of COPD=0.22, presenting a sensitivity of 70.13% and a specificity of 62.25%. The AUROC value for screening undiagnosed patients with clinically significant COPD was 0.68 (95% CI: 0.66–0.69). Moreover, the ten-fold cross validation reported an AUC of 0.72 (95% CI: 0.71–0.73), and the external validation presented an AUC of 0.69 (95% CI: 0.68–0.71). Conclusion: This prediction model can serve as a first-stage screening tool for undiagnosed COPD patients in primary care settings

Risk Factors for HIV-1 seroconversion among Taiwanese men visiting gay saunas who have sex with men

<p>Abstract</p> <p>Background</p> <p>Men having sex with men (MSM) accounts for 33.6% of all reported cases of HIV-1 infection in Taiwan. The aim of this study was to investigate the epidemiology of HIV-1 infection among MSM in gay saunas in Taiwan.</p> <p>Methods</p> <p>Patrons of 5 gay saunas were recruited for a weekly volunteer counseling and testing program from 2001 to 2005. Questionnaires were collected for a risk factor analysis. HIV-1 subtypes were determined using DNA sequencing and phylogenetic analyses.</p> <p>Results</p> <p>HIV-1 prevalence rates among MSM in gay saunas in 2001 through 2005 were 3.4%, 5.1%, 8.9%, 8.5%, and 8.3%, respectively. In total, 81 of 1, 093 (7.4%) MSM had HIV-1 infection. Fifty-two HIV-1 strains were genotyped, and all of them were subtype B. HIV-seropositive men were significantly younger than the seronegatives. Only 37.1% used condoms every time during sexual intercourse. A multivariate logistic regression analysis showed that the risk factors for HIV-1 were being uncircumcised (odds ratio (OR) = 2.19; 95% confidence interval (CI), 1.08~4.45); having sexual intercourse with at least 2 partners during each sauna visit (≥ 2 vs. ≤ 1, OR = 1.71; 95% CI, 1.02~2.89); and the role played during anal intercourse (versatile vs. an exclusively insertive role, OR = 2.76; 95% CI, 1.42~5.36).</p> <p>Conclusions</p> <p>Overall, 7.4% Taiwanese MSM participating in this study had HIV-1 subtype B infection. Uncircumcised, being versatile role during anal intercourse, and having sex with more than one person during each sauna visit were main risk factors for HIV-1 infection.</p

Deciphering the Preference and Predicting the Viability of Circular Permutations in Proteins

Circular permutation (CP) refers to situations in which the termini of a protein are relocated to other positions in the structure. CP occurs naturally and has been artificially created to study protein function, stability and folding. Recently CP is increasingly applied to engineer enzyme structure and function, and to create bifunctional fusion proteins unachievable by tandem fusion. CP is a complicated and expensive technique. An intrinsic difficulty in its application lies in the fact that not every position in a protein is amenable for creating a viable permutant. To examine the preferences of CP and develop CP viability prediction methods, we carried out comprehensive analyses of the sequence, structural, and dynamical properties of known CP sites using a variety of statistics and simulation methods, such as the bootstrap aggregating, permutation test and molecular dynamics simulations. CP particularly favors Gly, Pro, Asp and Asn. Positions preferred by CP lie within coils, loops, turns, and at residues that are exposed to solvent, weakly hydrogen-bonded, environmentally unpacked, or flexible. Disfavored positions include Cys, bulky hydrophobic residues, and residues located within helices or near the protein's core. These results fostered the development of an effective viable CP site prediction system, which combined four machine learning methods, e.g., artificial neural networks, the support vector machine, a random forest, and a hierarchical feature integration procedure developed in this work. As assessed by using the hydrofolate reductase dataset as the independent evaluation dataset, this prediction system achieved an AUC of 0.9. Large-scale predictions have been performed for nine thousand representative protein structures; several new potential applications of CP were thus identified. Many unreported preferences of CP are revealed in this study. The developed system is the best CP viability prediction method currently available. This work will facilitate the application of CP in research and biotechnology