The technology acceptance model (TAM) is one of the most widely used models of information technology (IT) adoption. According to TAM, IT adoption is influenced by two perceptions: usefulness and ease of use. In this study, we extend TAM to the mobile commerce context. We categorize the tasks performed on wireless handheld devices into three categories: (1) general tasks that do not involve transactions and gaming, (2) gaming tasks, and (3) transactional tasks. We propose a unified conceptual model for wireless technology adoption. In this model, task type moderates the effects of four possible determinants: perceived usefulness, perceived ease of use, perceived playfulness, and perceived security. We postulate that, under the mobile context, user intention to perform general tasks that do not involve transactions and gaming is influenced by perceived usefulness and perceived ease of use, user intention to play games is affected by perceived playfulness, and user intention to 124 FANG, CHAN, BRZEZINSKI, AND XU transact is influenced by perceived usefulness and perceived security. A survey was conducted to collect data about user perception of 12 tasks that could be performed on wireless handheld devices and user intention to use wireless technology. Multiple regression analyses supported the proposed research model. KEY WORDS AND PHRASES: mobile commerce, perceived ease of use, perceived playfulness, perceived security, perceived usefulness, TAM, task performance, task type, user intention, wireless handheld devices.THE CONVERGENCE OF MOBILE INTERNET and wireless communication technology has promised users "anytime, anywhere" access of information for work and personal communication. Such opportunities include mobile services that support mobile commerce transactions and process facilitation for managing personal activities, mobile office, and mobile operations [1]. However, certain factors hinder access, such as small screen display, limited bandwidth, and multiple functionalities of handheld devices.Research suggests that interface developers need to consider the interaction among the interface design of user tasks, form factors, and application objectives [7, 27]. Mobile commerce assumes that users primarily access the Internet or wireless applications away from their home or office while either on the move or stationary. Since mobile users have only limited time and cognitive resources for performing a task, the design of mobile applications is important. Anckar and D'Incau [2] suggest that services that emphasize mobile values (e.g., meeting time-critical and spontaneous needs) are more suitable for wireless devices. In designing mobile commerce applications, it is essential to determine which tasks are suitable for wireless applications [6] and how to implement the tasks.Human-computer interaction (HCI) studies tend to focus primarily on designing easy user interfaces. There has been little research that provides empirical evidence about how task implementation may affect user adoption of mobi...

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Background Percutaneous kyphoplasty (PKP) can effectively treat osteoporotic vertebral compression fractures (OVCFs). Although satisfactory clinical outcomes can be achieved, bone cement leakage remains a primary complication of PKP. Previous studies have found many high risk factors for bone cement leakage into the spinal canal; however, less attention to the posterior wall morphologies of different vertebral bodies may be one reason for the leakage. Here, we investigated the effect of posterior vertebral wall morphology in OVCF patients on bone cement leakage into the spinal canal during PKP. Methods Ninety-eight OVCF patients with plain computed tomography (CT) scans and three-dimensional (3D) reconstruction images from T6 to L5 were enrolled. 3D-CT and multiplanar reconstructions (MPR) were used to measure the concave posterior vertebral wall depth (PVWCD) and the corresponding midsagittal diameter of the nonfractured vertebral body (VBSD), and the PVWCD/VBSD ratio was calculated. All subjects were divided into the thoracic or lumbar groups based on the location of the measured vertebrae to observe the value and differences in the PVWCD between both groups. The differences in PVWCD and PVWCD/VBSD between the thoracic and lumbar groups were compared. Three hundred fifty-seven patients (548 vertebrae) who underwent PKP within the same period were also divided into the thoracic and lumbar groups. The maximal sagittal diameter (BCSD), the area of the bone cement intrusion into the spinal canal (BCA), and the spinal canal encroachment rate (BCA/SCA × 100%) were measured to investigate the effect of the thoracic and lumbar posterior vertebral wall morphologies on bone cement leakage into the spinal canal through the Batson vein during PKP. Results The PVWCDs gradually deepened from T6 to T12 (mean, 4.6 mm); however, the values gradually became shallower from L1 to L5 (mean, 0.6 mm). The PVWCD/VBSD ratio was approximately 16% from T6 to T12 and significantly less at 3% from L1 to L5 (P < 0.05). The rate of bone cement leakage into the spinal canal through the Batson vein was 10.1% in the thoracic group and 3.7% in the lumbar group during PKP. In the thoracic group, the BCSD was 3.1 ± 0.5 mm, the BCA was 30.2 ± 3.8 mm2, and the BCA/SCA ratio was 17.2 ± 2.0%. In the lumbar group, the BCSD was 1.4 ± 0.3 mm, the BCA was 14.8 ± 2.2 mm2, and the BCA/SCA ratio was 7.4 ± 1.0%. The BCSD, BCA and BCA/SCA ratio were significantly higher in the thoracic group than in the lumbar group (P < 0.05). Conclusions The PVWCD in the middle and lower thoracic vertebrae can help reduce bone cement leakage into the spinal canal by enabling avoiding bone cement distribution over the posterior 1/6 of the vertebral body during PKP. The effect of the difference between the thoracic and lumbar posterior vertebral wall morphology on bone cement leakage into the spinal canal through the Batson vein in OVCF patients during PKP is one reason that the rate of bone cement leakage into the thoracic spinal canal is significantly higher than that into the lumbar spinal canal.

Background Infection after vertebral augmentation (VA) often limits the daily activities of patients and even threatens their life. The operation may be one of the effective treatments if the patient suffers from intolerable severe pain, neurological deficits, and damage to spinal stability. This study aimed to investigate the clinical efficacy of the treatment of pyogenic spondylitis after vertebral augmentation (PSVA) with Single posterior debridement, vertebral body resection, and intervertebral bone graft fusion and internal fixation (sPVRIF). Methods The study was performed on 19 patients with PSVA who underwent VA at 4 hospitals in the region between January 2010 and July 2020. Nineteen patients were included. Among them, 16 patients underwent sPVRIF to treat the PSVA. Results A total of 2267 patients underwent VA at 4 hospitals in the region. Of the 19 patients with postoperative PSVA, suppurative spondylitis was misdiagnosed as an osteoporotic vertebral fracture(OVF) in 4 patients and they underwent VA. Besides osteoporosis, 18 patients had other comorbidities. The average interval between the first surgery and the diagnosis of PSVA was 96.4 days. Of the 19 patients, 16 received surgical treatment. The surgical time was 175.0±16.8 min, and the intraoperative blood loss was 465.6±166.0 mL. Pathogenic microorganisms were cultured in 12 patients. Conclusion PSVA is a severe complication that can even threaten the life of the patients. sPVRIF may be one of the effective treatments if the patient suffers from intolerable severe pain, neurological deficits, and damage to spinal stability.

Congenital orbital fibrosis is a non-familial, unilateral, distinct clinical entity, characterised by the presence of a diffusely infiltrating orbital mass and is extremely a rare disease. Congenital orbital fibrosis with combined fibrosis of extraocular muscles have not been reported previously. We treated an 8-year-old boy with the presence of a diffusely infiltrating orbital mass and fibrosis of extraocular muscles with secondary involvement of extraocular muscles. Clinical examination revealed left exotropia, hypotropia and fibrosis of extraocular muscle, an irregular, retrobulbar mass located within the orbit, incorporating the optic nerve, medial, superior, inferior and lateral rectus muscle. The CT, MRI and light microscopic studies confirmed the diagnosis. We performed exploration of the orbit, release and biopsy of scar tissue and strabismus surgery. Unlike other reported cases, our case was a progressive congenital disorder with combined fibrosis of extraocular muscle.

Background Surgeons recognize that using percutaneous kyphoplasty (PKP) under local anesthesia to treat osteoporotic vertebral fracture (OVF) prevents interference with the general situation of elderly patients suffering from multiple organ dysfunction. Surgeons can directly assess whether nerve injury occurs while the patient is awake. However, when patients with multiple osteoporotic vertebral fractures (m-OVFs) receive local anesthesia, fluoroscopy time often has to be increased, the operative time has to be extended, or the operation has to be terminated because of discomfort related to body posture. No relevant study has thus far been conducted on the type of anesthesia to administer to patients undergoing PKP for m-OVFs. This study aimed to determine which of the two types of anesthesia is more suitable for PKP for m-OVFs. Methods A retrospective study was conducted involving 159 patients who underwent PKP for m-OVFs from January 2016 to January 2020; 81 patients underwent PKP under general anesthesia (Group G), and 78 patients underwent PKP under local anesthesia (Group L). Clinical and adverse events were compared between the two groups. Results The intraoperative mean arterial pressure, average heart rate, average fluoroscopy times of each vertebral body, and operative time were less in Group G than in Group L. The visual analog scale (VAS) score was significantly lower after than before the operation. The anterior vertebral height (AVH), middle vertebral height (MVH), and kyphotic angle (KA) were significantly improved in both groups postoperatively. The improvement in VAS score, AVH, MVH, and KA in Group G were higher than those in Group L. No significant difference in the incidence of complications was observed between the two groups. Conclusion PKP under either general anesthesia or local anesthesia was reliable. Compared with PKP under local anesthesia, PKP under general anesthesia could more reliably maintain the stability of vital signs, alleviate preoperative pain in patients, and attain a better orthopedic effect. Moreover, the latter does not increase the complications of patients with m-OVFs. However, the high medical expense of PKP under general anesthesia is a factor to consider when choosing the type of anesthesia.

In recent years, service-oriented and ubiquitous technologies have experienced impressive development. As these services grow rapidly both in scale and type, effective and accurate service discovery methods play an increasingly important role in the search and selection of services that match consumer requirements and preferences. In order to discover the optimum service and enhance the effectiveness of discovered results, a semantic-based service discovery framework, consisting of user model, context model, service model and a service discovery process, was presented in this study. Then the personalized service ontology was introduced to adjust the service search range adaptively on the basis of the service ontology structure and user information. Furthermore, a semantic-based service discovery method was designed in the proposed framework, which enabled names, attributes and relations of services to be more accurately matched and mapped with user preferences. Finally, to evaluate the effectiveness and accuracy of this method, the simulation analysis was conducted based on service ontology, in which information on 102 separate services and 10 scenarios were extracted from actual data. The simulation results show that compared with the keywords-based method, the proposed semantic-based method shows an increase in recall rate, precision and F-measure. The simulation results also reveal that the proposed method improves service discovery efficiency and performs well in accuracy. Therefore, collaborative environments considered in service discovery can provide useful and effective guidance to study the service recommendation.

Primary malignant melanoma of the lacrimal sac is extremely rare. It is usually diagnosed at an advanced stage after excision or biopsy of a tumour. We treated a 59-year-old man with tearing and bloody discharge from the right eye. Clinical examination revealed a firm, localised mass at the inner canthus consistent with a lacrimal sac swelling. Sac washout demonstrated obstruction to entry into the lacrimal sac with a reflux of blood-stained fluid. The pathological findings and the immunohistochemical studies showed a malignant melanoma of the lacrimal sac. We performed radical surgery and radiation therapy. Follow-up 4 months after surgery revealed no evidence of recurrence. Because this tumour often presents with symptoms similar to dacryocystitis and may masquerade as a chronic dacryocystitis, ophthalmologists should be aware of this disease entity when encountered with patients with epiphora and mass in the medial canthal area.