A matrix factorization framework for jointly analyzing multiple nonnegative data

Nonnegative matrix factorization based methods provide one of the simplest and most effective approaches to text mining. However, their applicability is mainly limited to analyzing a single data source. In this paper, we propose a novel joint matrix factorization framework which can jointly analyze multiple data sources by exploiting their shared and individual structures. The proposed framework is flexible to handle any arbitrary sharing configurations encountered in real world data. We derive an efficient algorithm for learning the factorization and show that its convergence is theoretically guaranteed. We demonstrate the utility and effectiveness of the proposed framework in two real-world applications–improving social media retrieval using auxiliary sources and cross-social media retrieval. Representing each social media source using their textual tags, for both applications, we show that retrieval performance exceeds the existing state-of-the-art techniques. The proposed solution provides a generic framework and can be applicable to a wider context in data mining wherever one needs to exploit mutual and individual knowledge present across multiple data sources

Retrospective observational study on the incidence of incisional hernias after colorectal carcinoma resection with follow-up CT scan

Incisional hernia (IH) is the most frequent complication after colorectal carcinoma (CRC) resection. The incidence depends on the method of follow-up, where ultrasound yields a significant number of additional hernias compared to clinical examination alone. Not many studies have evaluated the value of computed tomography (CT) to diagnose IH. The CorreCT study is a retrospective cohort study of IH after CRC surgery by clinical examination and by CT, as reported in the medical files. Additional independent reviewing of all CTs by two radiologists was performed. From the oncological database (2004-2008) of the hospital, 598 patients with CRC were identified. The data of 448 consecutive patients who underwent surgery were analyzed. Tumors were resected by laparotomy in 366 patients (81.7 %), by laparoscopy in 76 patients (17.0 %) and by laparotomy after conversion in 6 patients (1.3 %). A clinical follow-up by the surgeon in 282 patients (62.9 %) with a mean duration of 33 months, yielded 49 patients with IH (17.4 %). The mean time of IH diagnosis (T1) was 19 months. Only 16 patients (33 %) underwent a hernia repair. For 363 patients (81.0 %), CT follow-up was available for a mean period of 30 months. In 84 patients (23.1 %), an IH was diagnosed with a mean T1 of 21 months. The review of all CTs by two independent radiologists yielded additional IH in 19 and 21 patients, respectively, increasing the IH rate to 29.1 and 29.7 %, respectively, and with a decrease in mean T1 to 14 months. The inter-observer agreement between the radiologists had a Kappa-statistic of 0.73 (95 % CI 0.65-0.81). For those patients with disagreement between the radiologists, a final agreement was made during an additional reviewing session of both radiologists, increasing the IH rate to 35.0 %. Comparing clinical follow-up, routine CT follow-up, and reassessed CT follow-up we found a statistically significant difference between the three methods of IH detection (p < 0.0001). CT follow-up can identify significantly more IH than clinical examination alone, in particular if the radiologist focuses on IH development. Furthermore, we showed that focused CT evaluation diagnosed IH 7 months earlier than routine CT and 5 months earlier than clinical follow-up alone

Retrospective observational study on the incidence of incisional hernias after reversal of a temporary diverting ileostomy following rectal carcinoma resection with follow-up CT scans

Wounds resulting from the closure of temporary stomas have a high risk of developing an incisional hernia (IH) with incidences around 30 % in studies designed to investigate this outcome. A temporary diverting ileostomy (TDI) is often used in patients after low anterior resection (LAR) for rectal cancer. The OSTRICH study is a retrospective cohort study of rectal cancer patients who had a LAR with a reversed TDI and at least one CT scan during follow-up. Two radiologists independently evaluated all abdominal CT scans to diagnose IH at the ileostomy wound and additionally, IH at the laparotomy site. From the oncological database of rectal cancer patients treated from 2003 till 2012 (n = 317) a cohort of 153 patients that fulfilled the inclusion criteria was identified. Rectal cancer resection was performed by laparoscopy in 53 patients (34.6 %) and by laparotomy in 100 patients (65.4 %). A total of 17 IH (11.1 %) was diagnosed at the former stoma site after a mean follow-up of 2.6 years. Of these, 8 IH were in patients who had a laparoscopic LAR (15.1 %) and 9 IH in patients who had an open LAR (9.0 %) (Fisher's exact test; p = 0.28). IH on the other abdominal wall incisions was reported in 69 patients (45.1 %). Of these, 10 patients underwent laparoscopic rectal surgery (18.9 %) and in 59 patients had open rectal surgery (59.0 %) (Fisher's exact test; p < 0.0001). We found a lower number of incisional hernias (11.1 %) after reversal of ileostomies than expected from the literature. In contrast to the findings at the ileostomy site, a very high frequency of IH (59.0 %) after LAR by laparotomy was found, which was significantly higher than after laparoscopic LAR