Calibration tests in multi-class classification: A unifying framework

In safety-critical applications a probabilistic model is usually required to be calibrated, i.e., to capture the uncertainty of its predictions accurately. In multi-class classification, calibration of the most confident predictions only is often not sufficient. We propose and study calibration measures for multi-class classification that generalize existing measures such as the expected calibration error, the maximum calibration error, and the maximum mean calibration error. We propose and evaluate empirically different consistent and unbiased estimators for a specific class of measures based on matrix-valued kernels. Importantly, these estimators can be interpreted as test statistics associated with well-defined bounds and approximations of the p-value under the null hypothesis that the model is calibrated, significantly improving the interpretability of calibration measures, which otherwise lack any meaningful unit or scale.Comment: Corrected version that 1) fixes the ECE evaluation with bins of uniform size (does not affect our conclusions and discussions) and 2) contains additional experimental results in the supplementary materia

GAP-independent functions of DLC1 in metastasis

Metastases are responsible for most cancer-related deaths. One of the hallmarks of metastatic cells is increased motility and migration through extracellular matrixes. These processes rely on specific small GTPases, in particular those of the Rho family. Deleted in liver cancer-1 (DLC1) is a tumor suppressor that bears a RhoGAP activity. This protein is lost in most cancers, allowing malignant cells to proliferate and disseminate in a Rho-dependent manner. However, DLC1 is also a scaffold protein involved in alternative pathways leading to tumor and metastasis suppressor activities. Recently, substantial information has been gathered on these mechanisms and this review is aiming at describing the potential and known alternative GAP-independent mechanisms allowing DLC1 to impair migration, invasion, and metastasis formation

Effect of RasGAP N2 Fragment-Derived Peptide on Tumor Growth in Mice

Peptides that interfere with the natural resistance of cancer cells to genotoxin-induced apoptosis may improve the efficacy of anticancer regimens. We have previously reported that a cell-permeable RasGAP-derived peptide (TAT-RasGAP317-326) specifically sensitizes tumor cells to genotoxin-induced apoptosis in vitro. Here, we examined the in vivo stability of a protease-resistant D-form of the peptide, RI·TAT-RasGAP317-326, and its effect on tumor growth in nude mice bearing subcutaneous human colon cancer HCT116 xenograft tumors. After intraperitoneal injection, RI·TAT-RasGAP317-326 persisted in the blood of nude mice for more than 1 hour and was detectable in various tissues and subcutaneous tumors. Tumor-bearing mice treated daily for 7 days with RI·TAT-RasGAP317-326 (1.65 mg/kg body weight) and cisplatin (0.5 mg/kg body weight) or doxorubicin (0.25 mg/kg body weight) displayed reduced tumor growth compared with those treated with either genotoxin alone (n = 5-7 mice per group; P = .004 and P = .005, respectively; repeated measures analysis of variance [ANOVA, two-sided]). This ability of the RI·TAT-RasGAP317-326 peptide to enhance the tumor growth inhibitory effect of cisplatin was still observed at peptide doses that were at least 150-fold lower than the dose lethal to 50% of mice. These findings provide the proof of principle that RI·TAT-RasGAP317-326 may be useful for improving the efficacy of chemotherapy in patient

RasGTPase-activating protein is a target of caspases in spontaneous apoptosis of lung carcinoma cells and in response to etoposide

p120 RasGTPase-activating protein (RasGAP), the main regulator of Ras GTPase family members, is cleaved at low caspase activity into an N-terminal fragment that triggers potent anti-apoptotic signals via activation of the Ras/PI-3 kinase/Akt pathway. When caspase activity is increased, RasGAP fragment N is further processed into two fragments that effectively potentiate apoptosis. Expression of RasGAP protein and its cleavage was assessed in human lung cancer cells with different histology and responsiveness to anticancer drug-induced apoptosis. Here we show that therapy-sensitive small lung carcinoma cell (SCLC) lines have lower RasGAP expression levels and higher spontaneous cleavage with formation of fragment N compared to therapy-resistant non-small cell lung carcinoma cell (NSCLC) lines. The first RasGAP cleavage event strongly correlated with the increased level of spontaneous apoptosis in SCLC. However, generation of protective RasGAP fragment N also related to the potency of SCLC to develop secondary therapy-resistance. In response to etoposide (ET), RasGAP fragment N was further cleaved in direct dependence on caspase-3 activity, which was more pronounced in NSCLC cells. Caspase inhibition, while effectively preventing the second cleavage of RasGAP, barely affected the first cleavage of RasGAP into fragment N that was always detectable in NSCLC and SCLC cells. These findings suggest that different levels of RasGAP and fragment N might play a significant role in the biology and different clinical course of both subtypes of lung neoplasms. Furthermore, constitutive formation of RasGAP fragment N can potentially contribute to primary resistance of NSCLC to anticancer therapy by ET but also to secondary therapy-resistance in SCL

Learning Design through the Lens of Service: A Qualitative Study

Twenty-four senior-level capstone engineering design projects were completed at a large, public, primarily undergraduate university involving 85 students (70 male and 15 female). All projects involved the design of equipment to facilitate physical activity for people with disabilities. The effects on: i) learning design, ii) attitude towards people with disabilities, iii) motivation to complete team design projects and iv) interdisciplinary collaboration were analyzed through 24 one-hour focus groups. We explored the student experience using a constructivist approach and grounded theory. Four major themes (with associated sub-themes) emerged from our data analysis: learning design (project management, iterative design process, and user-centered design), motivation to complete design (engineering, disabilities, user), perceptions of people with disabilities (previous experience, changed attitudes and beliefs), and multidisciplinary collaboration (etiquette presentation, communication between disciplines, defining roles and expectations). Students completing these projects were shown to appreciate user-centered design, exhibit greater motivation when able to meet and develop a relationship with their client in person, discuss altruistic factors regarding their capstone experience, and were able to develop strong multidisciplinary skills

Perforation in a patient with stercoral colitis and diverticulosis: who did it?

Stercoral colitis with perforation of the colon is an uncommon, yet life-threatening cause of the acute abdomen. No one defining symptom exists for stercoral colitis; it may present asymptomatically or with vague symptoms. Diagnostic delay may result in perforation of the colon resulting in complications, even death. Moreover, stercoral perforation of the colon can also present with localized left lower quadrant abdominal pain masquerading as diverticulitis. Diverticular diseases and stercoral colitis share similar pathophysiology; furthermore, they may coexist, further complicating the diagnostic dilemma. The ability to decide the cause of perforation in a patient with both stercoral colitis and diverticulosis has not been discussed. We, therefore, report this case of stercoral perforation in a patient with diverticulosis and include a discussion of the epidemiology, clinical presentation, and a review of helpful diagnostic clues for a rapid differentiation to allow for accurate diagnosis and treatment

Development of a GEM-TPC prototype

The use of GEM foils for the amplification stage of a TPC instead of a con- ventional MWPC allows one to bypass the necessity of gating, as the backdrift is suppressed thanks to the asymmetric field configuration. This way, a novel continuously running TPC, which represents one option for the PANDA central tracker, can be realized. A medium sized prototype with a diameter of 300 mm and a length of 600 mm will be tested inside the FOPI spectrometer at GSI using a carbon or lithium beam at intermediate energies (E = 1-3AGeV). This detector test under realistic experimental conditions should allow us to verify the spatial resolution for single tracks and the reconstruction capability for displaced vertexes. A series of physics measurement implying pion beams is scheduled with the FOPI spectrometer together with the GEM-TPC as well.Comment: 5 pages, 4 figures, Proceedings for 11th ICATTP conference in como (italy