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Transportation Safety and Environment 2020年第2期2卷 120-132页

作者： stephen a.arhin Adam Gatiba Howard University Transportation Research Center 23006th Street NWWashingtonDC 20059United States

The Washington,DC crash statistic report for the period from 2013 to 2015 shows that the city recorded about 41789 crashes at unsignalized intersections,which resulted in 14168 injuries and 51 *** economic cost of these fatalities has been estimated to be in the millions of *** is therefore necessary to investigate the predictability of the occurrence of theses crashes,based on pertinent factors,in order to provide mitigating *** research focused on the development of models to predict the injury severity of crashes using support vector machines(SVMs)and Gaussian naïve Bayes classifiers(GNBCs).The models were developed based on 3307 crashes that occurred from 2008 to *** SVM models and a GNBC model were *** most accurate model was the SVM with a radial basis kernel *** model predicted the severity of an injury sustained in a crash with an accuracy of approximately 83.2%.The GNBC produced the worst-performing model with an accuracy of 48.5%.These models will enable transport officials to identify crash-prone unsignalized intersections to provide the necessary countermeasures beforehand.

关键词： crashes unsignalized intersection support vector machines Gaussian naïve Bayes classifier injury severity

Effectiveness of modified pedestrian crossing signs in an urban area

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Journal of Traffic and Transportation Engineering(English Edition) 2022年第1期9卷 21-32页

作者： stephen a.arhin Adam Gatiba Melissa Anderson Babin Manandhar Melkamsew Ribbisso Ebenezer Acheampong Transportation Research Center Howard UniversityWashington DC 20059USA

The District of Columbia currently uses the standard pedestrian warning signs and diagonal arrow plaques at a substantial number of uncontrolled crosswalks within the ***, the widespread use of these measures appears to be ineffective in curbing the incidence of pedestrian involved crashes or pedestrian-vehicle conflicts. To compensate for the perceived lack of effectiveness of the standard pedestrian warning sign the District Department of Transportation developed a new side-of-street crossing sign to improve driver compliance based on pedestrian right-of-way *** study was aimed at determining the effectiveness(defined as the proportion of drivers approaching a crosswalk who stop or yield the right of way to a pedestrian in the crosswalk) of the experimental side-of-street pedestrian crossing sign compared to the standard sign, with and without rectangular rapid flashing beacons. Effectiveness of the side-of-street pedestrian sign and standard sign were observed at a total of 32 locations in the District over a one-year period using the “control” and “experimental” comparison approach. Video data for each location was obtained from March 2018 through February 2019 during typical weekdays for the morning and afternoon peak periods. The results of the study showed that the experimental signs with RRFBs provided higher driver compliance rates(yielding to pedestrians) compared to the standard signs for both the morning and afternoon peak periods. However, the differences in compliance rates for the experimental and standard signs were not statistically significant at a 95% confidence *** evaluation of the signs is recommended using the “before” and “after” approach in addition to an assessment of crash statistics at the selected locations.

关键词： Transportation engineering Pedestrian signs Crosswalk Compliance Driver yielding behavior District of Columbia

Optimization of transit total bus stop time models

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Journal of Traffic and Transportation Engineering(English Edition) 2016年第2期3卷 146-153页

作者： stephen arhin Errol Noel Melissa F.Anderson Lakeasha Williams Asteway Ribisso Regis Stinson Department of Civil and Environmental Engineering Howard University

Several factors influence bus transit reliability which includes bus stop conditions along the route, traffic conditions, route of travel and time of day. The overall transit bus reli- ability is generally affected by dwell time （DT）, the fare payment method, the bus stop location, and the number of passengers alighting or boarding. A new variable is defined in this study, total bus stop time （TBST）, which is the summation of DT and the time it takes a bus to effectively park at a bus stop and the re-entering the traffic stream. It is suggested that the overall bus transit reliability along routes could be improved if the TBST is mini- mized at bus stops. In this study, TBST models for bus stops located at mid-blocks and near intersections were developed based on multivariate regression analysis using ordinary least squares method. Data collection was conducted at 60 bus stops, 30 of which were near intersections and 30 at mid-blocks, in Washington DC during morning, mid-day and evening peak hours. The variables observed at each bus stop are as follows： number of passengers alighting or boarding, DT, TBST, bus stop type, bus pad, length number of lanes on approach to the bus stop, and permitted parking. Statistical inferences were based on 5% level of significance. From the results, it was inferred that the new variable, TBST, could potentially be used to improve scheduling and transit bus systems planning in a dense urban area.

关键词： Total bus stop time Dwell time Optimization Transit reliability Bus transit

Exciton-polaritons in a 2D hybrid organic-inorganic perovskite microcavity with the presence of optical Stark effect

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Chinese Physics B 2024年第3期33卷 551-555页

作者： Kenneth Coker 郑楚媛 Joseph Roger arhin Kwame Opuni-Boachie Obour Agyekum 张伟利 School of Information and Communication Engineering University of Electronic Science and Technology of ChinaChengdu 611731China Department of Electrical and Electronic Engineering Ho Technical UniversityHo 00233Ghana Telecommunication Engineering Department Kwame Nkrumah University of Science and TechnologyKumasi 00233Ghana

This study investigates the properties of exciton-polaritons in a two-dimensional(2D)hybrid organic-inorganic perovskite microcavity in the presence of optical Stark *** both steady and dynamic state analyses,strong coupling between excitons of perovskite and cavity photons is revealed,indicating the formation of polaritons in the perovskite ***,it is found that an external optical Stark pulse can induce energy shifts of excitons proportional to the pulse intensity,which modifies the dispersion characteristics of the polaritons.

关键词： exciton-polaritons perovskite microcavity optical Stark effect

Enhanced direct gaseous CO_(2) fixation into higher bio-succinic acid production and selectivity

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Journal of Environmental Sciences 2024年第9期143卷 164-175页

作者： Ziyi Yang Wanling Wu Qing Zhao Irini Angelidaki Samuel Gyebi arhin Dongliang Hua Yuxiao Zhao Hangyu Sun Guangqing Liu Wen Wang Biomass Energy and Environmental Engineering Research Center Beijing University of Chemical TechnologyBeijing 100029China College of Chemical Engineering Beijing University of Chemical TechnologyBeijing 100029China Department of Chemical and Biochemical Environmental Engineering Technical University of DenmarkDK-2800Kgs LyngbyDenmark Energy Research Institute Qilu University of Technology(Shandong Academy of Sciences)Shandong Provincial Key Laboratory of Biomass Gasification TechnologyJinan 250014China

Utilizing CO_(2)for bio-succinic acid production is an attractive approach to achieve carbon capture and recycling(CCR)with simultaneous production of a useful platform *** succinogenes and Basfia succiniciproducens were selected and investigated as microbial ***,the type and concentration of inorganic carbon concentration and glucose concentration were evaluated.6 g C/L MgCO_(3)and 24 g C/L glucose were found to be the optimal basic operational conditions,with succinic acid production and carbon yield of over 30 g/L and over 40%,***,for maximum gaseous CO_(2)fixation,carbonate was replaced with CO_(2)at different ***“less carbonate more CO_(2)”condition of the inorganic carbon source was set as carbonate:CO_(2)=1:9(based on the mass of carbon).This condition presented the highest availability of CO_(2)by well-balanced chemical reaction equilibrium and phase equilibrium,showing the best performance with regarding CO_(2)fixation(about 15 mg C/(L·hr)),with suppressed lactic acid *** to key enzymes analysis,the ratio of phosphoenolpyruvate carboxykinase to lactic dehydrogenase was enhanced at high ratios of gaseous CO_(2),which could promote glucose conversion through the succinic acid *** further increase gaseous CO_(2)fixation and succinic acid production and selectivity,stepwise CO_(2)addition was evaluated.50%-65%increase in inorganic carbon utilization was obtained coupled with 20%-30%increase in succinic acid *** was due to the promotion of the succinic acid branch of the glucose metabolism,while suppressing the pyruvate branch,along with the inhibition on the conversion from glucose to lactic acid.

关键词： Succinic acid CO_(2) fixation Actinobacillus succinogenes Basfia succiniciproducens Lactic acid

Improving Mobility on Segments with Closely Spaced Intersections in Urban Areas

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Open Journal of Civil Engineering 2019年第1期9卷 46-56页

作者： stephen A. arhin Adam Gatiba Melissa Anderson Melkamsew Ribbisso Babin Manandhar Howard University Transportation Research Center Washington DC USA

In this research, a strategy to improve mobility and reduce delay on road segments is explored via modeling and simulation. Thirty selected corridors with combination of signalized and unsignalized intersections were identified for this study. Each segment consists of at least one AWSC and two signalized intersections at which field data were obtained (lane configurations, signal timing, traffic volumes, etc.). The selected AWSC intersections on the segments were within 305 m (1000 feet) from the upstream or downstream signalized intersections. Synchro software program was utilized to model the existing condition of the segments based on which the strategy for mobility improvement was explored. The field data were used as input in Synchro software application to model two scenarios: existing or the “before” scenario, and the “after” scenario. The unsignalized intersections were signalized (and optimized) in the “after” scenario. The measures of effectiveness used to assess the efficiency of the strategy were average travel speed, control delay and 95th percentile queue length. The analyses were conducted for both the morning (AM) and evening (PM) peak periods. The results of the analyses showed reductions in control delay and 95th percentile queue lengths that were statistically significant, while the average travel speed of vehicles significantly increased at 5% level of significance. The evaluation determined that the signalization of some unsignalized intersections (which are 305 m or less from existing signalized intersections) may improve mobility despite the fact that these locations do not meet the MUTCD warrants for signalization. These findings would aid transportation engineers and planners to consider and evaluate this option when making decisions on signalization of intersections in urban areas.

关键词： Mobility Throughput Control Delay Average System Travel Speed Level of Service

Patron Survey of Acceptable Wait Times at Transit Bus Stops in the District of Columbia

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Open Journal of Civil Engineering 2019年第4期9卷 268-280页

作者： stephen A. arhin P. E. PTOE Adam Gatiba Melissa Anderson Melkamsew Ribbisso Babin Manandhar Howard University Transportation Research Center NW Washington DC USA

The wait time of bus patrons at bus stops is one of several measures for assessing reliability of transit services, especially in urban areas. The uncertainty associated with waiting affects bus patrons’ perception of quali of the service provided. Studies in this subject area have therefore been of interest to transit service agencies and officials. This paper presents the findings of a study conducted to determine patrons’ maximum acceptable wait times (beyond the scheduled arrival time) at bus stops in an urban area. In all, 3387 bus patrons at 71 selected bus stops were surveyed over a period of 9 months. The results of the survey showed that the least acceptable wait time beyond the scheduled arrival time was 1 minute, while the maximum acceptable wait time was reported to be 20 minutes. Also, only one-third (33%) of the total number of patrons surveyed were willing to wait up to 5 minutes beyond the scheduled arrival time of buses. In addition, patrons are willing to wait longer in warm weather. On average, white patrons were found to have the least maximum acceptable wait times, followed by Hispanics, Asians, and then Blacks.

关键词： Acceptable Wait Time Bus Patrons District of Columbia

Oral Mucosa Graft Glanuloplasty—Ten Years in Retrospect

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Open Journal of Urology 2024年第5期14卷 317-323页

作者： Kwaku Addai arhin Appiah Patrick Opoku Manu Maison George Amoah Department of Surgery School of Medicine and Dentistry Kwame Nkrumah University of Science and Technology Kumasi Ghana Department of Surgery University of Cape Coast Cape Coast Ghana Department of Surgery Komfo Anokye Teaching Hospital Kumasi Ghana

Penile glans amputation is a tragic complication of circumcision. Beyond the psychological trauma parents go through, they have to deal with the lower urinary tract symptoms including acute urine retention their baby boys suffer due to meatal stenosis from the scaring process that ensues. We report on the cosmetic and functional outcomes in two patients ten years after neo-glans reconstruction following total glans amputation as a complication of circumcision and discuss the lessons learned over the period.

关键词： Penile Glans Amputation Circumcision Complication Neo-Glans Reconstruction Meatal Stenosis Urinary Tract Symptoms

The Antihypertensive Effect of Hydro-methanolic Extract of Tulbaghia acutiloba *** L-NAME induced Hypertensive Rats

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Clinical Complementary Medicine and Pharmacology 2023年第3期3卷 50-59页

作者： Isaiah arhin Kogi Moodley Himansu Baijnath Usri H.Ibrahim Irene Mackraj Discipline of Human Physiology School of Laboratory Medicine and Medical SciencesCollege of Health SciencesUniversity of KwaZulu-NatalDurban 4000South Africa Ward Herbarium School of Life SciencesUniversity of KwaZulu-NatalDurban 4000South Africa

Background:Traditional use of Tulbaghia acutiloba(TA)in South Africa includes treating various illnesses,such as infectious diseases and ***,the effect of this indigenous plant on renal and haematological parameters(as indicators of antihypertensive efficacy)has not been investigated ***:This study aimed to evaluate the change of renal and haematological parameters after treatment with the hydro-methanolic extract of the leaf of Tulbaghia acutiloba *** L-NAME-induced hypertensive ***:Male albino Wistar rats received an oral dose of 50 mg·kg^(-1)body weight(bw)of N𝜔-Nitro-L-arginine methyl ester hydrochloride(L-NAME)daily for 5 *** groups(7 animals in each group)were identified to receive different treatments as concurrent daily doses of(40,60 and 80 mg·kg^(-1)bw),ramipril(10 mg·kg^(-1)bw)(positive control)and water(hypertension model).Mean arterial blood pressure was measured weekly using the tail-cuffmethod.A 24-hour urine sample was collected for each rat *** day 36,the rats were euthanized,and blood samples were collected for the determination of renal function and haematological *** mRNA gene expression was performed for NF-kB,Ho1 and ***:The treatment of the hypertensive rats with TA resulted in a significant reduction in the mean arterial blood pressure,with a pronounced effect observed in the 80 mg·kg^(-1)dose of TA compared to the positive *** TA-treated group showed increased creatinine clearance(Ccr),urine volume and a reduction in serum crea-tinine,proteinuria and urine protein-creatinine ratio(UPr/UCr).TA treatment also decreased lipid peroxidation in renal tissues and erythrocytes while increasing SOD,CAT,GSH and NO ***,red cell distribu-tion width(RDW),white blood cells(WBC),neutrophil to lymphocyte ratio(NLR),lymphocyte to monocyte ratio(LMR),platelet and mean platelet volume(MPV)were significantly reduced in the TA and ramipril treated groups with the maxim

关键词： Tulbaghia acutiloba Renal function Haematological parameters Hypertension Antioxidant

Competition Networks as a New Insight into the Determinants of Firm Technological and Market Performance

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Innovation and Development Policy 2022年第2期 105-128页

作者： Gupeng Zhang Shan Lu Sen Du Ishmael arhin Joseph Iesué Dujuan Huang Xiao Wang School of Public Policy and Management University of Chinese Academy of SciencesBeijing 100049China Sino-Danish College University of Chinese Academy of SciencesBeijing 100049China Institute of Tea Science Nanjing Agricultural UniversityNanjingJiangsu 210095China Academy of Future Education National Yang Ming Chiao Tung UniversityTaiwan 11221China School of Business Administration Anhui University of Finance and EconomicsBengbuAnhui 233030China International Business School Suzhou Xi’an Jiaotong-Liverpool UniversitySuzhouJiangsu 215123China

Based on the global patents of 109 mobile phone vendors filed from 1992 to 2016 and sales data from 2002to 2016, this study formulates technological and market competition networks. We find that an increasingly large number of firms joined the market, leading to a competition network of increasingly larger scale and greater density. We also propose indicators to measure competitive intensity, which reflects the extent to which the firms are competing against each other. We examine the role of competitive intensity in mediating firms’ performance. We employ a weighted least squares regression model for the empirical analysis. The empirical results confirm the significant role of competitive intensity in determining firm performance. However, in technological and market competition networks, competitive intensity generates essentially different mediating impacts. For technological competition, competitive intensity positively mediates the impact between the leaders’ and followers’ technological performances. There is an asymmetric mediating effect that enlarges the gap between the technological performances of leading vendors and their followers. Accordingly, competitive intensity may generate different impacts on the technological performance of leaders and followers. In comparison, the competitive intensity embedded in the market competition network has a symmetrical role in mediating the mutual impact between the leaders’ and followers’ market performances, that is, it neither enlarges nor narrows the market performance gap between leaders and followers. Therefore, when creating a development strategy, firm managers need to account for their competitors’ behaviors, carefully analyze the significance of these behaviors, and adjust their strategic arrangements in a timely manner.

关键词： competition network competitive intensity technological performance market performance mobile phone vendor