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1.
BMC Musculoskelet Disord ; 25(1): 29, 2024 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-38166887

RESUMO

BACKGROUND: To evaluate the outcome of shoulder arthroscopy-assisted implantation of three-dimensional (3D)-printed titanium pads for recurrent shoulder dislocation with glenoid bone defects. METHODS: From June 2019 to May 2020, the clinical efficacy of 3D printed titanium pad implantation assisted by shoulder arthroscopy, for the treatment of recurrent shoulder dislocations with shoulder glenoid defects was retrospectively analyzed. The American Shoulder and Elbow Surgeons (ASES) shoulder, Rowe, and Constant scores were recorded before surgery and at 3 months, 6 months, 1 year, and 2 years after surgery. 3D computed tomography (CT) and magnetic resonance imaging were used to evaluate the location of the glenoid pad, bone ingrowth, joint degeneration, and osteochondral damage. RESULTS: The mean age of the 12 patients was 21.4 (19-24) years and the mean follow-up time was 27.6 (24-35) months. The Visual Analog Scale score significantly improved from 5.67 ± 1.98 preoperatively to 0.83 ± 0.58 postoperatively (p = 0.012). The postoperative ASES score was significantly increased to 87.91 ± 3.47 compared with preoperative ASES score (46.79 ± 6.45) (p < 0.01). Rowe and Constant scores also improved from 22.5 ± 12.34 and 56.58 ± 7.59 preoperatively to 90.83 ± 4.69 and 90.17 ± 1.89 at 2 years postoperatively, respectively. CT performed 2 years after surgery showed that the pad perfectly replenished the bone-defective part of the shoulder glenoid and restored the articular surface curvature of the shoulder glenoid in the anterior-posterior direction, and the bone around the central riser of the pad was tightly united. Magnetic resonance imaging 2 years after surgery showed that the humeral head osteochondral bone was intact, and there was no obvious osteochondral damage. CONCLUSIONS: 3D printed titanium pads are a reliable, safe, and effective surgical procedure for treating recurrent shoulder dislocations with glenoid bone defects.


Assuntos
Instabilidade Articular , Luxação do Ombro , Articulação do Ombro , Humanos , Adulto Jovem , Adulto , Luxação do Ombro/diagnóstico por imagem , Luxação do Ombro/cirurgia , Articulação do Ombro/diagnóstico por imagem , Articulação do Ombro/cirurgia , Titânio , Seguimentos , Estudos Retrospectivos , Instabilidade Articular/cirurgia , Artroscopia/métodos , Impressão Tridimensional , Recidiva
2.
Microb Cell Fact ; 22(1): 230, 2023 Nov 08.
Artigo em Inglês | MEDLINE | ID: mdl-37936187

RESUMO

The physical states and chemical components of bulk sludge determine the occurrence and development of membrane fouling in membrane bioreactors. Thus, regulation of sludge suspensions can provide new strategies for fouling control. In this study, we used "top-down" enrichment to construct a synthetic anti-fouling consortium (SAC) from bio-cake and evaluate its roles in preventing membrane fouling. The SAC was identified as Massilia-dominated and could almost wholly degrade the alginate solution (1,000 mg/L) within 72 h. Two-dimensional Fourier transformation infrared correlation spectroscopy (2D-FTIR-CoS) analysis demonstrated that the SAC induced the breakage of glycosidic bond in alginates. The co-cultivation of sludge with a low dosage of SAC (ranging from 0 to 1%) led to significant fouling mitigation, increased sludge floc size, and decreased unified membrane fouling index value (0.55 ± 0.06 and 0.11 ± 0.05). FTIR spectra and X-ray spectroscopy analyses demonstrated that the addition of SAC decreased the abundance of the O-acetylation of polysaccharides in extracellular polymeric substances. Secondary derivatives analysis of amide I spectra suggested a strong reduction in the α-helix/(ß-sheet + random coil) ratio in the presence of SAC, which was expected to enhance cell aggregation. Additionally, the extracellular secretions of SAC could both inhibit biofilm formation and strongly disperse the existing biofilm strongly during the biofilm incubation tests. In summary, this study illustrates the feasibility and benefits of using SAC for fouling control and provides a new strategy for fouling control.


Assuntos
Incrustação Biológica , Esgotos , Esgotos/química , Incrustação Biológica/prevenção & controle , Membranas Artificiais , Biofilmes , Polissacarídeos , Reatores Biológicos , Alginatos
3.
Front Immunol ; 14: 1113560, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36817486

RESUMO

Kidney transplantation (KT) is an ultimate treatment of end-stage chronic kidney disease, which can meet a lot of complications induced by immune system. With under-controlled immunosuppression, the patient will obtain a good prognosis. Otherwise, allograft disfunction will cause severe organ failure and even immune collapse. Acute or chronic allograft dysfunction after KT is related to Th17, Treg, and Th17/Treg to a certain extent. Elevated Th17 levels may lead to acute rejection or chronic allograft dysfunction. Treg mainly plays a protective role on allografts by regulating immune response. The imbalance of the two may further aggravate the balance of immune response and damage the allograft. Controlling Th17 level, improving Treg function and level, and adjusting Th17/Treg ratio may have positive effects on longer allograft survival and better prognosis of receptors.


Assuntos
Transplante de Rim , Humanos , Linfócitos T Reguladores , Células Th17 , Imunidade , Imunomodulação
4.
Orthop Surg ; 15(2): 648-654, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36519211

RESUMO

OBJECTIVE: Acromioclavicular joint dislocation is one of the most common shoulder injuries in young men. With the advancement of minimally invasive technology, arthroscopy of acromioclavicular joint dislocation has been recognized for its good curative effect. This study aimed to explore the technical details and clinical efficacy of a modified minimally invasive endoscopic treatment for acromioclavicular joint dislocation. METHODS: Clinical data of patients receiving the three-incision endoscopic treatment were retrospectively reviewed between July 2013 and July 2019. A total of 72 patients with acromioclavicular joint dislocation of Rockwood type III (n = 42) and type V (n = 30) were included in this study. Postoperative routine radiography was performed to evaluate acromioclavicular joint reduction and fixation. In addition, functional recovery of the shoulder joint was assessed using the American Shoulder and Elbow Surgeons (ASES) and Constant-Murley scores. Differences between the preoperative and postoperative data were compared using paired t-tests. RESULTS: All patients underwent loop plate elastic fixation under endoscopy during 24 to 48 months of follow-up. Postoperative radiography showed that the acromioclavicular joint achieved anatomical reduction. The ASES score (91.1 ± 4.2) was significantly improved compared to the preoperative ASES score (62.4 ± 3.1) (t = 46.65, P < 0.0001). The Constant-Murley score (93.1 ± 4.6) was also significantly higher than that before the operation (40.7 ± 6.4) (t = 56.41, P < 0.0001). No postoperative complications occurred. During follow-up, four patients had mild acromioclavicular joint degeneration but no obvious pain symptoms. CONCLUSION: The modified three-incision endoscopic technique optimizes the surgical incision, reduces trauma, is minimally invasive, and provides rapid rehabilitation with satisfactory clinical outcomes.


Assuntos
Articulação Acromioclavicular , Luxações Articulares , Luxação do Ombro , Ferida Cirúrgica , Masculino , Humanos , Luxações Articulares/diagnóstico por imagem , Luxações Articulares/cirurgia , Estudos Retrospectivos , Articulação Acromioclavicular/diagnóstico por imagem , Articulação Acromioclavicular/cirurgia , Articulação Acromioclavicular/lesões , Luxação do Ombro/cirurgia , Resultado do Tratamento , Artroscopia/métodos
5.
Clin Immunol ; 245: 109169, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-36332815

RESUMO

BACKGROUND: Sepsis is a life-threatening condition. The incidence of severe sepsis is increasing. Sepsis is often complicated with organ dysfunctions. Cyclic helix B peptide (CHBP) is a peptide derivant of erythropoietin with powerful tissue-protective efficacies. However, the role of CHBP in sepsis-induced injury remains unclear. MATERIAL AND METHODS: Lyso-phosphatidylserine (LPS) was used to induce sepsis in human pulmonary microvascular endothelial cells (HPMECs). Cell growth was detected using Cell Counting Kit-8. Cell permeability was measured using fluorescein isothiocyanate (FITC)-dextran. Cecal ligation and puncture (CLP) method was applied to induce sepsis and CHBP was provided to test its efficacy. Western blot assays were used to evaluate gene expression. RESULTS: Administration of CHBP ameliorated LPS-induced injury in HPMECs dose-dependently. Administration of CHBP decreased the permeability of LPS-treated HPMEC cells in a same way as well. Furthermore, we identified that recombinant CHBP protein (Re-CHBP) ameliorated CLP-induced injury in vivo. Finally, we found that administration of NF-κB activator, TNF-α, abolished the function of Re-CHBP in LPS-treated HPMEC cells. CONCLUSION: CHBP ameliorated sepsis-induced injury dose dependently both in vitro and in vivo through decreasing the permeability of HPMEC cells via suppressing NF-κB signaling and inflammation. Present findings highlight the importance of CHBP/NF-κB signaling in septic injury and provide new insights into therapeutic strategies for sepsis-induced injury.


Assuntos
NF-kappa B , Sepse , Humanos , NF-kappa B/metabolismo , Lipopolissacarídeos , Peptídeos Cíclicos/uso terapêutico , Células Endoteliais , Sepse/complicações , Sepse/tratamento farmacológico , Sepse/metabolismo
6.
Shock ; 58(5): 366-373, 2022 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-36155398

RESUMO

ABSTRACT: Background: Uneven body-surface thermal distribution is a manifestation of hypoperfusion and can be quantified by infrared thermography. Our aim was to investigate whether body-surface thermal inhomogeneity could accurately evaluate the severity of patients at risk of hypoperfusion. Methods: This was a prospective cohort study in which infrared thermography images were taken from unilateral legs of critically ill patients at high risk of hypoperfusion in a cardiac surgical intensive care unit. For each patient, five body-surface thermal inhomogeneity parameters, including standard deviation (SD), kurtosis, skewness, entropy, and low-temperature area rate (LTAR), were calculated. Demographic, clinical, and thermal characteristics of deceased and living patients were compared. The risk of mortality and capillary refill time (CRT) were chosen as the primary outcome and benchmarking parameter for hypoperfusion, respectively. The area under the receiver operating characteristic curve (AUROC) was used to evaluate predictive accuracy. Results: Three hundred seventy-three patients were included, and 55 (14.7%) died during hospital stay. Of inhomogeneity parameters, SD (0.738) and LTAR (0.768) had similar AUROC to CRT (0.757) for assessing mortality risk. Besides, there was a tendency for LTAR (1%-3%-7%) and SD (0.81°C-0.88°C-0.94°C) to increase in normotensive, hypotensive, and shock patients. These thermal parameters are associated with CRT, lactate, and blood pressure. The AUROC of a combined prediction incorporating three thermal inhomogeneity parameters (SD, kurtosis, and entropy) was considerably higher at 0.866. Conclusions: Body-surface thermal inhomogeneity provided a noninvasive and accurate assessment of the severity of critically ill patients at high risk of hypoperfusion.


Assuntos
Estado Terminal , Termografia , Humanos , Termografia/métodos , Estudos Prospectivos , Área Sob a Curva , Unidades de Terapia Intensiva
7.
World J Crit Care Med ; 11(5): 311-316, 2022 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-36160936

RESUMO

In this editorial, we comment on the current development and deployment of data science in intensive care units (ICUs). Data in ICUs can be classified into qualitative and quantitative data with different technologies needed to translate and interpret them. Data science, in the form of artificial intelligence (AI), should find the right interaction between physicians, data and algorithm. For individual patients and physicians, sepsis and mechanical ventilation have been two important aspects where AI has been extensively studied. However, major risks of bias, lack of generalizability and poor clinical values remain. AI deployment in the ICUs should be emphasized more to facilitate AI development. For ICU management, AI has a huge potential in transforming resource allocation. The coronavirus disease 2019 pandemic has given opportunities to establish such systems which should be investigated further. Ethical concerns must be addressed when designing such AI.

8.
Arthrosc Tech ; 11(5): e805-e811, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35646585

RESUMO

The limitations of transferring the coracoid process along with the conjoined tendon are coracoacromial arch damage, technical difficulty, and nerve injury. The long head of the biceps tendon (LHBT) proximal transposition technique has a weaker sling effect and a risk of nerve injury. The arthroscopic subscapularis augmentation technique may have risks of shoulder external rotation restriction and subscapularis transection. Herein, we introduce an arthroscopic technique for the transfer of the LHBT for subscapularis augmentation to address these risks. Indications of this technique were patients younger than 45 years of age who engage in competitive sports, require forceful external rotation and abduction, have a related capsule-ligament insufficiency, and have a glenoid bone loss <25%. The steps include detaching the LHBT at the upper edge of the pectoralis major, transecting and braiding the LHBT, establishing a scapular tunnel, placing a guide suture through the upper third of the subscapular and scapular tunnel, passing the LHBT through the established tunnels, and fixating the LHBT. This technique achieves stability of the anterior shoulder by transecting and transferring the distal end of the LHBT to press on the upper third of the subscapularis muscle.

9.
ESC Heart Fail ; 9(4): 2635-2644, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-35611916

RESUMO

AIMS: Recombinant human brain natriuretic peptide (rh-BNP) is commonly used as a decongestive therapy. This study aimed to investigate the instant effects of rh-BNP on cardiac output and venous return function in post-cardiotomy patients with congestive heart failure (CHF). METHODS AND RESULTS: Twenty-four post-cardiotomy heart failure patients were enrolled and received a standard loading dose of rh-BNP. Haemodynamic monitoring was performed via a pulmonary artery catheter before and after the administration of rh-BNP. The cardiac output and venous return functions were estimated by depicting Frank-Starling and Guyton curves. After rh-BNP infusion, variables reflecting cardiac congestion and venous return function, such as pulmonary artery wedge pressure, mean systemic filling pressure (Pmsf) and venous return resistance index (VRRI), reduced from 15 ± 3 to 13 ± 3 mmHg, from 32 ± 7 to 28 ± 7 mmHg and from 6.7 ± 2.6 to 5.7 ± 1.8 mmHg min m2 /L, respectively. Meanwhile, cardiac index, stroke volume index, and the cardiac output function curve remained unchanged per se. The decline in Pmsf [-13% (-22% to -8%)] and VRRI [-12% (-25% to -5%)] was much greater than that in the systemic vascular resistance index [-7% (-14% to 0%)]. In the subgroup analysis of reduced ejection fraction (<40%) patients, the aforementioned changes were more significant. CONCLUSIONS: rh-BNP might ameliorate venous return rather than cardiac output function in post-cardiotomy CHF patients.


Assuntos
Insuficiência Cardíaca , Peptídeo Natriurético Encefálico , Débito Cardíaco , Coração , Insuficiência Cardíaca/tratamento farmacológico , Humanos , Peptídeo Natriurético Encefálico/uso terapêutico , Volume Sistólico
10.
Front Med (Lausanne) ; 9: 827850, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35602475

RESUMO

Objective: Evaluate the effect of the combination of clindamycin with low-dose trimethoprim-sulfamethoxazole (TMP/SMX) regimen on sever Pneumocystis pneumonia (PCP) after renal transplantation. Method: 20 severe PCP patients after renal transplantation were included in this historical-control, retrospective study. A 10 patients were treated with the standard dose of TMP/SMX (T group), the other 10 patients were treated with the combination of clindamycin and low dose TMP/SMX (CT group). Results: Although there was no significant difference in the hospital survival between the two groups, the CT protocol improved the PaO2/FiO2 ratio more significantly and rapidly after the 6th ICU day (1.51 vs. 0.38, P = 0.014). CT protocol also ameliorated the pulmonary infiltration and the lactate dehydrogenase level more effectively. Moreover, the CT protocol reduced the incidence of pneumomediastinum (0 vs. 50%, P = 0.008), the length of hospital staying (26.5 vs. 39.0 days, P = 0.011) and ICU staying (12.5 vs. 22.5 days, P = 0.008). Furthermore, more thrombocytopenia (9/10 vs. 3/10, P = 0.020) was emerged in the T group than in the CT group. The total adverse reaction rate was much lower in the CT group than in the T group (8/80 vs. 27/80, P < 0.001). Consequently, the dosage of TMP/SMX was reduced in 8 patients, while only 2 patients in the CT group received TMP/SMX decrement (P = 0.023). Conclusion: The current study proposed that clindamycin combined with low-dose TMP/SMX was more effective and safer the than single use of TMP/SMX for severe PCP patients after renal transplantation (NCT04328688).

11.
Int J Surg Case Rep ; 90: 106677, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34952311

RESUMO

INTRODUCTION: Open injury of the medial malleolus is relatively rare, and it can cause instability of the ankle joint and affect the walking function of the lower extremity. We describe an original plan for the reconstruction of medial malleolus defects using the bone sliding technique and report as follows. CASE PRESENTATION: A 48-year-old female presented with an isolated open injury to her right ankle by a traffic accident. The skin of the medial ankle was severely contaminated with mud, and the medial malleolus, part of the Talus's cartilage and soft tissue, were defective. The anterior tibial artery was cut, and the anterior and posterior tibial tendons were ruptured. CONCLUSION: We describe the reconstruction of the medial malleolus using a bone sliding technique. At two years follow-up, she had a good outcome with a nearly painless, stable ankle with functional plantarflexion but restricted dorsiflexion. The original method is a new choice for the reconstruction of the medial malleolus.

12.
Ann Transl Med ; 9(15): 1261, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34532398

RESUMO

OBJECTIVE: To discuss the pathogenesis of severe coronavirus disease 2019 (COVID-19) infection and the pharmacological effects of glucocorticoids (GCs) toward this infection. To review randomized controlled trials (RCTs) using GCs to treat patients with severe COVID-19, and investigate whether GC timing, dosage, or duration affect clinical outcomes. Finally. to discuss the use of biological markers, respiratory parameters, and radiological evidence to select patients for improved GC therapeutic precision. BACKGROUND: COVID-19 has become an unprecedented global challenge. As GCs have been used as key immunomodulators to treat inflammation-related diseases, they may play key roles in limiting disease progression by modulating immune responses, cytokine production, and endothelial function in patients with severe COVID-19, who often experience excessive cytokine production and endothelial and renin-angiotensin system (RAS) dysfunction. Current clinical trials have partially proven this efficacy, but GC timing, dosage, and duration vary greatly, with no unifying consensus, thereby creating confusion. METHODS: Publications through March 2021 were retrieved from the Web of Science and PubMed. Results from cited references in published articles were also included. CONCLUSIONS: GCs play key roles in treating severe COVID-19 infections. Pharmacologically, GCs could modulate immune cells, reduce cytokine and chemokine, and improve endothelial functions in patients with severe COVID-19. Benefits of GCs have been observed in multiple clinical trials, but the timing, dosage and duration vary across studies. Tapering as an option is not widely accepted. However, early initiation of treatment, a tailored dosage with appropriate tapering may be of particular importance, but evidence is inconclusive and more investigations are needed. Biological markers, respiratory parameters, and radiological evidence could also help select patients for specific tailored treatments.

13.
Front Immunol ; 12: 684496, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34149726

RESUMO

Acute kidney injury (AKI) is a common and potential life-threatening disease in patients admitted to hospital, affecting 10%-15% of all hospitalizations and around 50% of patients in the intensive care unit. Severe, recurrent, and uncontrolled AKI may progress to chronic kidney disease or end-stage renal disease. AKI thus requires more efficient, specific therapies, rather than just supportive therapy. Mesenchymal stem cells (MSCs) are considered to be promising cells for cellular therapy because of their ease of harvesting, low immunogenicity, and ability to expand in vitro. Recent research indicated that the main therapeutic effects of MSCs were mediated by MSC-derived extracellular vesicles (MSC-EVs). Furthermore, compared with MSCs, MSC-EVs have lower immunogenicity, easier storage, no tumorigenesis, and the potential to be artificially modified. We reviewed the therapeutic mechanism of MSCs and MSC-EVs in AKI, and considered recent research on how to improve the efficacy of MSC-EVs in AKI. We also summarized and analyzed the potential and limitations of EVs for the treatment of AKI to provide ideas for future clinical trials and the clinical application of MSC-EVs in AKI.


Assuntos
Injúria Renal Aguda/terapia , Vesículas Extracelulares/transplante , Transplante de Células-Tronco Mesenquimais , Células-Tronco Mesenquimais/citologia , Injúria Renal Aguda/metabolismo , Injúria Renal Aguda/patologia , Animais , Citocinas/metabolismo , Vesículas Extracelulares/química , Hospitalização , Humanos , Células-Tronco Mesenquimais/fisiologia
14.
Biomed Pharmacother ; 133: 111089, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33378983

RESUMO

Osteoarthritis is a chronic, systemic and inflammatory disease. However, the pathogenesis and understanding of RA are still limited. Ubiquitin-specific protease 13 (USP13) belongs to the deubiquitinating enzyme (DUB) superfamily, and has been implicated in various cellular events. Nevertheless, its potential on RA progression has little to be investigated. In the present study, we found that USP13 expression was markedly up-regulated in synovial tissue samples from patients with RA, and was down-regulated in human fibroblast-like synoviocytes (H-FLSs) stimulated by interleukin-1ß (IL-1ß), tumor necrosis factor alpha (TNF-α) or lipopolysaccharide (LPS). We then showed that over-expressing USP13 markedly suppressed inflammatory response, oxidative stress and apoptosis in H-FLSs upon IL-1ß or TNF-α challenge, whereas USP13 knockdown exhibited detrimental effects. In addition, USP13-induced protective effects were associated with the improvement of nuclear factor erythroid 2-related factor 2 (Nrf-2) and the repression of Casapse-3. Furthermore, phosphatase and tensin homolog (PTEN) expression was greatly improved by USP13 in H-FLSs upon IL-1ß or TNF-α treatment, whereas phosphorylated AKT expression was diminished. In response to IL-1ß or TNF-α exposure, nuclear transcription factor κB (NF-κB) signaling pathway was activated, whereas being significantly restrained in H-FLSs over-expressing USP13. Mechanistically, USP13 directly interacted with PTEN. Of note, we found that USP13-regulated cellular processes including inflammation, oxidative stress and apoptotic cell death were partly dependent on AKT activation. Furthermore, USP13 over-expression effectively inhibited osteoclastogenesis and osteoclast-associated gene expression. The in vivo experiments finally confirmed that USP13 dramatically repressed synovial hyperplasia, inflammatory cell infiltration, cartilage damage and bone loss in collagen-induced arthritis (CIA) mice via the same molecular mechanisms detected in vitro. Taken together, these findings suggested that targeting USP13 may provide feasible therapies for RA.


Assuntos
Apoptose , Artrite Experimental/prevenção & controle , Remodelação Óssea , Endopeptidases/metabolismo , Articulações/enzimologia , Osteoartrite/prevenção & controle , Estresse Oxidativo , PTEN Fosfo-Hidrolase/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Proteases Específicas de Ubiquitina/metabolismo , Idoso , Animais , Artrite Experimental/enzimologia , Artrite Experimental/genética , Artrite Experimental/patologia , Células Cultivadas , Colágeno Tipo II , Endopeptidases/genética , Humanos , Hiperplasia , Articulações/patologia , Masculino , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos DBA , Pessoa de Meia-Idade , Osteoartrite/enzimologia , Osteoartrite/genética , Osteoartrite/patologia , Osteoclastos/enzimologia , Osteoclastos/patologia , Osteogênese , PTEN Fosfo-Hidrolase/genética , Transdução de Sinais , Sinoviócitos/enzimologia , Sinoviócitos/patologia , Proteases Específicas de Ubiquitina/genética
15.
Sensors (Basel) ; 19(11)2019 May 29.
Artigo em Inglês | MEDLINE | ID: mdl-31146376

RESUMO

Crowdsensing has emerged as an efficient and inexpensive way to perform specialized tasks by leveraging external crowds. In some crowdsensing systems, different tasks may have different requirements, and there may be precedence constraints among them, such as the Unmanned Aerial Vehicle (UAV) crowdsensing systems. Moreover, minimizing the total execution time is a regular target for finishing the crowdsensing tasks with precedence constraints. As far as we know, only a few existing studies consider the precedence constraints among crowdsensing tasks, and none of them can minimize the total execution time simultaneously. To tackle this challenge, an efficient allocation mechanism for tasks with precedence constraints is first proposed, which can minimize the total execution time. Then, a case study is given to show how to fit our mechanism in the UAV crowdsensing system. Finally, the simulation results show that the proposed mechanisms have good approximate optimal ratios under different parameter settings and are efficient for the UAV crowdsensing system as well.

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