3,139 research outputs found

    NETWORK DESIGN FOR THE TEMPORAL AND SPATIAL COLLABORATION WITH SERVICE CLASS IN DELIVERY SERVICES

    Get PDF
    The COVID-19 pandemic has significantly impacted e-commerce and the delivery service sector. As lockdowns and social distancing measures were put in place to slow the spread of the virus, many brick-and-mortar stores were forced to close, leading to an increase in online shopping. This situation led to a surge in demand for delivery services as more people turned to the internet to purchase goods. However, this increase in demand also created several challenges for delivery companies. They experienced delays in delivering packages due to increased volume, limited staff, and disruptions to supply chains. It led to more competition and increased pressure on delivery companies to improve their services and delivery times. To overcome such competition, collaboration among small and medium-sized delivery companies can be a good way to compete with larger delivery companies. By working together, small and medium-sized companies can combine their resources and expertise to offer more extensive coverage and competitive prices than they could individually. This can help them to gain market share and expand their customer base. This study proposes a network design model for collaboration with service class in delivery services considering multi-time horizon. The problem to be considered is deciding which company is dedicated to delivering certain types of items, such as regular or refrigerated items, in designated regions in each time horizon. During the agreed-upon timeframe, the companies operate, using each other's infrastructure (such as vehicles and facilities) and sharing delivery centers for the coalition's benefit to improve efficiency and reduce costs. We also propose a multi-objective, nonlinear programming model that maximizes the incremental profit of participating companies and a linearization methodology to solve it. The max-sum criterion and Shapley value allocation methods are applied to find the best solution and ensure a fair distribution of profits among the collaborating group. The efficiency of the suggested model is shown through a numerical illustration

    Rapid and selective concentration of bacteria, viruses, and proteins using alternating current signal superimposition on two coplanar electrodes

    Get PDF
    Dielectrophoresis (DEP) is usually effective close to the electrode surface. Several techniques have been developed to overcome its drawbacks and to enhance dielectrophoretic particle capture. Here we present a simple technique of superimposing alternating current DEP (high-frequency signals) and electroosmosis (EO; low-frequency signals) between two coplanar electrodes (gap: 25 mu m) using a lab-made voltage adder for rapid and selective concentration of bacteria, viruses, and proteins, where we controlled the voltages and frequencies of DEP and EO separately. This signal superimposition technique enhanced bacterial capture (Escherichia coli K-12 against 1-mu m-diameter polystyrene beads) more selectively (>99%) and rapidly (similar to 30 s) at lower DEP (5 Vpp) and EO (1.2 Vpp) potentials than those used in the conventional DEP capture studies. Nanometer-sized MS2 viruses and troponin I antibody proteins were also concentrated using the superimposed signals, and significantly more MS2 and cTnI-Ab were captured using the superimposed signals than the DEP (10 Vpp) or EO (2 Vpp) signals alone (p < 0.035) between the two coplanar electrodes and at a short exposure time (1 min). This technique has several advantages, such as simplicity and low cost of electrode fabrication, rapid and large collection without electrolysis

    Comparison of the Clinical Outcomes of Open Surgery Versus Arthroscopic Surgery for Chronic Refractory Lateral Epicondylitis of the Elbow

    Get PDF
    Numerous surgical options have been introduced for the treatment of chronic refractory lateral epicondylitis of the elbow, but it remains unclear which option is superior. The clinical outcomes of an open surgery group and an arthroscopic surgery group were evaluated, and the results of the 2 procedures were compared. From among patients with lateral epicondylitis refractory to 6 months of conservative treatment, 68 patients satisfying study criteria were recruited. Open surgery was performed in 34 cases (group 1), and arthroscopic surgery was performed in 34 cases (group 2). Compared with preoperatively, the 2 groups had significantly improved values for grip strength, range of motion, and Disabilities of the Arm, Shoulder and Hand score at 12 months postoperatively. Group 1 had significantly greater improvements in grip strength and visual analog scale pain score compared with group 2 (P=.048 vs P=.006). Group 2 had significantly greater (P=.045) improvement in pronation compared with group 1. Group 2 returned to work sooner than group 1. On the questionnaire regarding satisfaction with surgery 24 months postoperatively, 4 patients (12%) in group 2 reported dissatisfaction compared with no patients in group 1. Open surgery and arthroscopic surgery both yielded good clinical results. Nonetheless, for patients requiring muscle strength or having severe pain at work, open surgery would be more effective

    Bone-added osteotome sinus floor elevation with simultaneous placement of non-submerged sand blasted with large grit and acid etched implants: a 5-year radiographic evaluation

    Get PDF
    PURPOSE: Implant survival rates using a bone-added osteotome sinus floor elevation (BAOSFE) procedure with simultaneous placement of a non-submerged sand blasted with large grit and acid etched (SLA) implant are well documented at sites where native bone height is less than 5 mm. This study evaluated the clinical results of non-submerged SLA Straumann implants placed at the time of the BAOSFE procedure at sites where native bone height was less than 4 mm. Changes in graft height after the BAOSFE procedure were also assessed using radiographs for 5 years after the implant procedure. METHODS: The BAOSFE procedure was performed on 4 patients with atrophic posterior maxillas with simultaneous placement of 7 non-submerged SLA implants. At least 7 standardized radiographs were obtained from each patient as follows: before surgery, immediately after implant placement, 6 months after surgery, every year for the next 3 years, and after more than 5 years had passed. Clinical and radiographic examinations were performed at every visit. Radiographic changes in graft height were calculated with respect to the implant's known length and the original sinus height. RESULTS: All implants were stable functionally, as well as clinically and radiographically, during the follow-up. Most of the radiographic reduction in the grafted bone height occurred in the first 2 years; reduction after 2 years was slight. CONCLUSIONS: The simultaneous placement of non-submerged SLA implants using the BAOSFE procedure is a feasible treatment option for patients with severe atrophic posterior maxillas. However, the grafted bone height is reduced during the healing period, and patients must be selected with care.ope

    Possible link between Arctic Sea ice and January PM10 concentrations in South Korea

    Get PDF
    In this study, we investigated the possible teleconnection between PM10 concentrations in South Korea and Arctic Sea ice concentrations at inter-annual time scales using observed PM10 data from South Korea, NCEP R2 data, and NOAA Sea Ice Concentration (SIC) data from 2001 to 2018. From the empirical orthogonal function (EOF) analysis, we found that the first mode (TC1) was a large-scale mode for PM10 in South Korea and explained about 27.4% of the total variability. Interestingly, the TC1 is more dominantly influenced by the horizontal ventilation effect than the vertical atmospheric stability effect. The pollution potential index (PPI), which is defined by the weighted average of the two ventilation effects, is highly correlated with the TC1 of PM10 at a correlation coefficient of 0.75, indicating that the PPI is a good measure for PM10 in South Korea at inter-annual time scales. Regression maps show that the decrease of SIC over the Barents Sea is significantly correlated with weakening of high pressure over the Ural mountain range region, the anomalous high pressure at 500 hPa over the Korean peninsula, and the weakening of the Siberian High and Aleutian low. Moreover, these patterns are similar to the correlation pattern with the PPI, suggesting that the variability of SIC over the Barents Sea may play an important role in modulating the variability of PM10 in South Korea through teleconnection from the Barents Sea to the Korean peninsula via Eurasia

    Characteristics of injury of the corticospinal tract and corticoreticular pathway in hemiparetic patients with putaminal hemorrhage

    Get PDF
    BACKGROUND: No study on the characteristics of injury of the corticospinal tract (CST) or corticoreticular pathway (CRP) in patients with putaminal hemorrhage has been reported. In this study, using diffusion tensor tractography, we attempted to investigate the characteristics of injury of the CST and CRP in hemiparetic patients with putaminal hemorrhage. METHOD: Fifty seven consecutive patients with putaminal hemorrhage and 57 healthy control subjects were recruited for this study. Diffusion tensor imaging was performed during the early period (8 ~ 30 days) after onset. We defined injury of the CST or CRP in terms of the configuration (discontinuation of a neural tract) or abnormal DTT parameters (the fractional anisotrophy value or fiber number was more than two standard deviations lower than that of normal control subjects). The Motricity Index, the modified Brunnstrom Classification, and the Functional Ambulation Categories were used for evaluation of motor function. RESULTS: Among 57 patients, injury of the CST was found in 41 patients (71.9%) and injury of the CRP was found in 50 patients (87.8%), respectively, and 37 patients (64.9%) had injury of both the CST and CRP. All three motor functions of patients with injury of both the CST and CRP were significantly lower than those of patients with injury of either the CST or CRP (p < 0.05). CONCLUSION: Our results indicate that the putaminal hemorrhage frequently accompanies injury of both the CST and CRP, and the CRP appears to be more vulnerable to putaminal hemorrhage than the CST. These findings suggest the necessity for evaluation of both the CRP and the CST in patients with putaminal hemorrhage

    Solid–liquid interface temperature measurement of evaporating droplet using thermoresponsive polymer aqueous solution

    Get PDF
    The present study aims to measure the solid–liquid interface temperature of an evaporating droplet on a heated surface using a thermoresponsive polymer. Poly(N-isopropylacrylamide) (pNIPAM) was used owing to its sensitive optical and mechanical properties to the temperature. We also measured the refractive index variation of the pNIPAM solution by using the surface plasmon resonance imaging (SPRi). In particular, the present study proposed a new method to measure the solid–liquid interface temperature using the correlation among reflectance, refractive index, and temperature. It was found that the reflectance of a pNIPAM solution decreased after the droplet deposition. The solid–liquid interface temperature, estimated from the reflectance, showed a lower value at the center of the droplet, and it gradually increased along the radial direction. The lowest temperature at the contact line region is present because of the maximum evaporative cooling. Moreover, the solid–liquid interface temperature deviation increased with the surface temperature, which means solid–liquid interface temperature should be considered at high temperature to predict the evaporation flux of the droplet accurately
    corecore