The Performance Evaluation of the Listed Security Companies in China Based on the DEA Model

Abstract With the continuous development of domestic stock market, the listed security companies have stepped into a stable growth period, the study of their performance becomes also deeper. This paper firstly introduces the methods of evaluating the performance of the listed security companies, and discusses the DEA method in detail. Then we evaluate the corporate performance of 16 domestic security companies by the DEA method. Finally we analyses the empirical results from three aspects, which are technical efficiency, pure technical efficiency and scale efficiency. This paper evaluates the performance of the listed security companies with a more scientific method

Evaluating team-based, lecture-based, and hybrid learning methods for neurology clerkship in China: a method-comparison study

BACKGROUND: Neurology is complex, abstract, and difficult for students to learn. However, a good learning method for neurology clerkship training is required to help students quickly develop strong clinical thinking as well as problem-solving skills. Both the traditional lecture-based learning (LBL) and the relatively new team-based learning (TBL) methods have inherent strengths and weaknesses when applied to neurology clerkship education. However, the strengths of each method may complement the weaknesses of the other. Combining TBL with LBL may produce better learning outcomes than TBL or LBL alone. We propose a hybrid method (TBL + LBL) and designed an experiment to compare the learning outcomes with those of pure LBL and pure TBL. METHODS: One hundred twenty-seven fourth-year medical students attended a two-week neurology clerkship program organized by the Department of Neurology, Sun Yat-Sen Memorial Hospital. All of the students were from Grade 2007, Department of Clinical Medicine, Zhongshan School of Medicine, Sun Yat-Sen University. These students were assigned to one of three groups randomly: Group A (TBL + LBL, with 41 students), Group B (LBL, with 43 students), and Group C (TBL, with 43 students). The learning outcomes were evaluated by a questionnaire and two tests covering basic knowledge of neurology and clinical practice. RESULTS: The practice test scores of Group A were similar to those of Group B, but significantly higher than those of Group C. The theoretical test scores and the total scores of Group A were significantly higher than those of Groups B and C. In addition, 100% of the students in Group A were satisfied with the combination of TBL + LBL. CONCLUSIONS: Our results support our proposal that the combination of TBL + LBL is acceptable to students and produces better learning outcomes than either method alone in neurology clerkships. In addition, the proposed hybrid method may also be suited for other medical clerkships that require students to absorb a large amount of abstract and complex course materials in a short period, such as pediatrics and internal medicine clerkships

Therapeutic Strategies Targeting Cancer Stem Cells and Their Microenvironment

Cancer stem cells (CSCs) have been demonstrated in a variety of tumors and are thought to act as a clonogenic core for the genesis of new tumor growth. This small subpopulation of cancer cells has been proposed to help drive tumorigenesis, metastasis, recurrence and conventional therapy resistance. CSCs show self-renewal and flexible clonogenic properties and help define specific tumor microenvironments (TME). The interaction between CSCs and TME is thought to function as a dynamic support system that fosters the generation and maintenance of CSCs. Investigation of the interaction between CSCs and the TME is shedding light on the biologic mechanisms underlying the process of tumor malignancy, metastasis, and therapy resistance. We summarize recent advances in CSC biology and their environment, and discuss the challenges and future strategies for targeting this biology as a new therapeutic approach

A U-shaped association of tracheostomy timing with all-cause mortality in mechanically ventilated patients admitted to the intensive care unit: A retrospective cohort study

ObjectivesTo evaluate the association of tracheostomy timing with all-cause mortality in patients with mechanical ventilation (MV).MethodIt’s a retrospective cohort study. Adult patients undergoing invasive MV who received tracheostomy during the same hospitalization based on the Medical Information Mart for Intensive Care-III (MIMIC-III) database, were selected. The primary outcome was the relationship between tracheostomy timing and 90-day all-cause mortality. A restricted cubic spline was used to analyze the potential non-linear correlation between tracheostomy timing and 90-day all-cause mortality. The secondary outcomes included free days of MV, incidence of ventilator-associated pneumonia (VAP), free days of analgesia/sedation in the intensive care unit (ICU), length of stay (LOS) in the ICU, LOS in hospital, in-ICU mortality, and 30-day all-cause mortality.ResultsA total of 1,209 patients were included in this study, of these, 163 (13.5%) patients underwent tracheostomy within 4 days after intubation, while 647 (53.5%) patients underwent tracheostomy more than 11 days after intubation. The tracheotomy timing showed a U-shaped relationship with all-cause mortality, patients who underwent tracheostomy between 5 and 10 days had the lowest 90-day mortality rate compared with patients who underwent tracheostomy within 4 days and after 11 days [84 (21.1%) vs. 40 (24.5%) and 206 (31.8%), P < 0.001].ConclusionThe tracheotomy timing showed a U-shaped relationship with all-cause mortality, and the risk of mortality was lowest on day 8, but a causal relationship has not been demonstrated

Size-resolved and bulk activation properties of aerosols in the North China Plain

Size-resolved and bulk activation properties of aerosols were measured at a regional/suburban site in the North China Plain (NCP), which is occasionally heavily polluted by anthropogenic aerosol particles and gases. A Cloud Condensation Nuclei (CCN) closure study is conducted with bulk CCN number concentration (NCCN) and calculated CCN number concentration based on the aerosol number size distribution and size-resolved activation properties. The observed CCN number concentration (NCCN-obs) are higher than those observed in other locations than China, with average NCCN-obs of roughly 2000, 3000, 6000, 10 000 and 13 000 cm−3 at supersaturations of 0.056, 0.083, 0.17, 0.35 and 0.70%, respectively. An inferred critical dry diameter (Dm) is calculated based on the NCCN-obs and aerosol number size distribution assuming homogeneous chemical composition. The inferred cut-off diameters are in the ranges of 190–280, 160–260, 95–180, 65–120 and 50–100 nm at supersaturations of 0.056, 0.083, 0.17, 0.35 and 0.7%, with their mean values 230.1, 198.4, 128.4, 86.4 and 69.2 nm, respectively. Size-resolved activation measurements show that most of the 300 nm particles are activated at the investigated supersaturations, while almost no particles of 30 nm are activated even at the highest supersaturation of 0.72%. The activation ratio increases with increasing supersaturation and particle size. The slopes of the activation curves for ambient aerosols are not as steep as those observed in calibrations with ammonium sulfate suggesting that the observed aerosols is an external mixture of more hygroscopic and hydrophobic particles. The calculated CCN number concentrations (NCCN-calc) based on the size-resolved activation ratio and aerosol number size distribution correlate well with the NCCN-obs, and show an average overestimation of 19%. Sensitivity studies of the CCN closure show that the NCCN at each supersaturation is well predicted with the campaign average of size-resolved activation curves. These results indicate that the aerosol number size distribution is critical in the prediction of possible CCN. The CCN number concentration can be reliably estimated using time-averaged, size-resolved activation efficiencies without accounting for the temporal variations

Decreased Netrin-1 and Correlated Th17/Tregs Balance Disorder in Aβ1–42 Induced Alzheimer’s Disease Model Rats

There is increasing evidence indicating that inflammation represents a key pathological component of Alzheimer’s disease (AD). A possible factor that may contribute to this process is netrin-1, a neuronal guidance molecule. This molecule has been shown to exert an unexpected immunomodulatory function. However, the potential changes and correlations of netrin-1 with T helper 17/regulatory T cells (Th17/Tregs) as related to inflammation in AD has yet to be examined. In this study, netrin-1 and Th17/Tregs balance were investigated, and the relationship among netrin-1, Th17/Tregs and cognitive function were analyzed in a rat model of AD. In this model, a bilateral intracerebroventricular administration of Amyloid β1-42 (Aβ1–42) was used to produce spatial learning and memory deficits, as well as increased neuronal apoptosis, which were detected 7 days after injection for AD7d group and 14 days for AD14d group. Netrin-1 concentrations were significantly down regulated in both serum and cerebrospinal fluid (CSF) of these AD rats, effects which were strongly correlated with cognitive deficits. Increased levels of interleukin (IL)-17 and deceased IL-10 were observed in both the circulation and CSF and were also correlated with the percent of time spent in the target quadrant of AD in these rats. These changes resulted in netrin-1 concentrations being negatively correlated with IL-17 but positively correlated with IL-10 concentrations in the serum and CSF. We also found that the Th17/Tregs balance was disrupted in these AD rats. Collectively, these findings reveal that the reduction in netrin-1 and the correlated disruption of Th17/Tregs balance in AD rats may diminish the immunosuppressive effect of netrin-1 on Th17/Tregs in AD pathogenesis

Prevalence of Stroke and Hypoperfusion in Patients With Isolated Vertigo and Vascular Risk Factors

Background and Purpose: The aim of this study was to determine the prevalence and associated factors of stroke and hypoperfusion among patients with isolated vertigo and vascular risk factors.Methods: We studied 157 patients with isolated vertigo who had undergone multimodal magnetic resonance imaging. Magnetic resonance angiography (MRA) was used to measure the diameters of vertebrobasilar arteries and to evaluate morphologic changes to vessels. Measurements obtained included length of the basilar artery and curvature index for the vertebral artery (VA). Perfusion-weighted imaging (PWI) was performed to determine relative cerebral blood flow, relative cerebral blood volume (rCBV), time to peak (TTP), and mean transit time for two mirror regions of interest (ROIs) in each map. Regional hypoperfusion of the cerebellum was considered significant when TTP and mean transit time (MTT) were present in ≥2 adjacent slices.Results: The prevalence of stroke in patients with isolated vertigo and vascular risk factors was 24.8% (n = 39). Visual assessment revealed cerebellar hypoperfusion in 57.6% (68/118) of non-stroke patients. Multivariate logistic regression indicated that diabetes mellitus (P = 0.049, OR = 2.758), VA stenosis or hypoplasia (P = 0.023, OR = 3.486), and relative TTP of cerebellum (P = 0.002, OR = 3.197) were independent risk factors for stroke and LVA curvature index (P = 0.026, OR = 2.049), VA stenosis and hypoplasia (P = 0.009, OR = 2.977) were independent risk factors for hypoperfusion.Conclusions: The prevalence of stroke and hypoperfusion is higher in patients with isolated vertigo and vascular risk factors, compared with matched controls. Potential risk factors include diabetes mellitus, VA stenosis or hypoplasia, and enlarged VA curvature index