On the consistency of multiclass classification methods

Binary classification is a well studied special case of the classification problem. Statistical properties of binary classifiers, such as consistency, have been investigated in a variety of settings. Binary classification methods can be generalized in many ways to handle multiple classes. It turns out that one can lose consistency in generalizing a binary classification method to deal with multiple classes. We study a rich family of multiclass methods and provide a necessary and sufficient condition for their consistency. We illustrate our approach by applying it to some multiclass methods proposed in the literature.

Self-management of cancer treatment-related fatigue, nausea, vomiting and oral mucositis in Chinese cancer patients

Background: Treatment-related symptoms continue to place a significant burden on many cancer patients. Many side effects require patients to engage in a range of self-management actions. While some studies have explored self-management of treatment-related side effects in Western settings, very few studies were identified that described the self-management practices of cancer patients in China. Objective: The purposes of this study are to: (1) Investigate Chinese cancer patients. self-management behaviours in dealing with the fatigue, nausea/vomiting and oral mucositis that result from treatment, as well as the perceived effectiveness of these behaviours and related self-efficacy in performing them. (2) Explore factors influencing symptom self-management behaviours using the Cancer Symptom Self-management Framework based on Grey, Knafl and McCorkle.s (2006) self-management framework as a guide. Methods: This study was divided into two phases. Phase One consisted of the translation and modification of two instruments. The adaptation of these instruments to ensure applicability in the Chinese context was achieved through semi-structured interviews with six cancer patients, and content evaluation with eight experienced oncology nurses. A pilot study was conducted with nine cancer patients to trial the questionnaire set in the Chinese context. Based on the results of Phase One, Phase Two involved a cross-sectional survey of Chinese cancer patients undergoing cancer treatment using these instruments. A total of 277 chemotherapy patients with fatigue and/or nausea and vomiting, and 100 radiotherapy patients with oral mucositis were surveyed. Results: Participants in this study reported a variety of self-management behaviours to cope with fatigue, nausea, vomiting and oral mucositis. There are some consistencies as well disparities between strategies that are frequently used and those rated as effective. For fatigue self-management, participants were more likely to use strategies related to rest and sleep, while activity enhancement strategies were rated as achieving higher relief. For nausea and vomiting self-management, dietary modification and taking medication were most frequently used and rated as moderately effective. Psychological strategies were used by more than a third of participants and were rated as mildly effective. Some other infrequently used strategies, such as distraction by keeping busy and acupressure, were rated as moderately effective. For oral mucositis self-management, having soft, bland food and keeping the mouth moisturised were most frequently reported and they were rated as achieving moderate relief. A prescribed mouthwash was used by most but not all participants and brought moderate relief. In general, patients had low-to-moderate self-efficacy in nausea and vomiting self-management behaviours, moderate self-efficacy in fatigue self-management behaviours, and low-to-moderate self-efficacy in oral mucositis self-management behaviours. In terms of the factors influencing symptom self-management, different predictors were identified affecting engagement in fatigue, nausea/vomiting and oral mucositis self-management behaviours. Self-efficacy scores of different behaviours were consistently found to be a positive predictor of the relief level from corresponding behaviours, after controlling for other variables. Perceived social support from health care professionals was identified as an important factor influencing nausea and vomiting self-management behaviours, while neighbourhood support was important for fatigue self-management. In addition, symptom distress was identified as an important factor influencing nausea and vomiting self-management. Conclusion: Similar to reports from overseas, Chinese cancer patients initiate a wide range of self-management behaviours in response to treatment-related side effects. While some behaviours were reported to provide relief, many did not. Given these results, this study has a number of practical implications for health care professionals, particularly in relation to developing tailored self-management programs for fatigue, nausea, vomiting and oral mucositis. Additionally, this study suggests a number of theoretical implications and directions for future research. It is envisaged that these recommendations may pave the way for further studies understanding and promoting cancer symptom self-management in Chinese people affected by cancer.

Numerical methods for second-order stochastic differential equations

We seek numerical methods for second‐order stochastic differential equations that reproduce the stationary density accurately for all values of damping. A complete analysis is possible for scalar linear second‐order equations (damped harmonic oscillators with additive noise), where the statistics are Gaussian and can be calculated exactly in the continuous‐time and discrete‐time cases. A matrix equation is given for the stationary variances and correlation for methods using one Gaussian random variable per timestep. The only Runge–Kutta method with a nonsingular tableau matrix that gives the exact steady state density for all values of damping is the implicit midpoint rule. Numerical experiments, comparing the implicit midpoint rule with Heun and leapfrog methods on nonlinear equations with additive or multiplicative noise, produce behavior similar to the linear case.

Broadening of transgenic adenocarcinoma of the mouse prostate (TRAMP) model to represent late stage androgen depletion independent cancer

BACKGROUND The transgenic adenocarcinoma of the mouse prostate (TRAMP) model closely mimics PC-progression as it occurs in humans. However, the timing of disease incidence and progression (especially late stage) makes it logistically difficult to conduct experiments synchronously and economically. The development and characterization of androgen depletion independent (ADI) TRAMP sublines are reported. METHODS Sublines were derived from androgen-sensitive TRAMP-C1 and TRAMP-C2 cell lines by androgen deprivation in vitro and in vivo. Epithelial origin (cytokeratin) and expression of late stage biomarkers (E-cadherin and KAI-1) were evaluated using immunohistochemistry. Androgen receptor (AR) status was assessed through quantitative real time PCR, Western blotting, and immunohistochemistry. Coexpression of AR and E-cadherin was also evaluated. Clonogenicity and invasive potential were measured by soft agar and matrigel invasion assays. Proliferation/survival of sublines in response to androgen was assessed by WST-1 assay. In vivo growth of subcutaneous tumors was assessed in castrated and sham-castrated C57BL/6 mice. RESULTS The sublines were epithelial and displayed ADI in vitro and in vivo. Compared to the parental lines, these showed (1) significantly faster growth rates in vitro and in vivo independent of androgen depletion, (2) greater tumorigenic, and invasive potential in vitro. All showed substantial downregulation in expression levels of tumor suppressor, E-cadherin, and metastatis suppressor, KAI-1. Interestingly, the percentage of cells expressing AR with downregulated E-cadherin was higher in ADI cells, suggesting a possible interaction between the two pathways. CONCLUSIONS The TRAMP model now encompasses ADI sublines potentially representing different phenotypes with increased tumorigenicity and invasiveness.