Coordinating visualizations of polysemous action: Values added for grounding proportion

We contribute to research on visualization as an epistemic learning tool by inquiring into the didactical potential of having students visualize one phenomenon in accord with two different partial meanings of the same concept. 22 Grade 4-6 students participated in a design study that investigated the emergence of proportional-equivalence notions from mediated perceptuomotor schemas. Working as individuals or pairs in tutorial clinical interviews, students solved non-symbolic interaction problems that utilized remote-sensing technology. Next, they used symbolic artifacts interpolated into the problem space as semiotic means to objectify in mathematical register a variety of both additive and multiplicative solution strategies. Finally, they reflected on tensions between these competing visualizations of the space. Micro-ethnographic analyses of episodes from three paradigmatic case studies suggest that students reconciled semiotic conflicts by generating heuristic logico-mathematical inferences that integrated competing meanings into cohesive conceptual networks. These inferences hinged on revisualizing additive elements multiplicatively. Implications are drawn for rethinking didactical design for proportions. © 2013 FIZ Karlsruhe

Treatment of hilar cholangiocarcinoma (Klatskin tumors) with hepatic resection or transplantation

Background: Because of the rarity of hilar cholangiocarcinoma, its prognostic risk factors have not been sufficiently analyzed. This retrospective study was undertaken to evaluate various pathologic risk factors which influenced survival after curative hepatic resection or transplantation. Methods: Between 1981 and 1996, 72 patients (43 males and 29 females) with hilar cholangiocarcinoma underwent hepatic resection (34 patients) or transplantation (38 patients) with curative intent. Medical records and pathologic specimens were reviewed to examine the various prognostic risk factors. Survival was calculated by the method of Kaplan- Meier using the log rank test with adjustment for the type of operation. Survival statistics were calculated first for each kind of treatment separately, and then combined for the calculation of the final significance value. Results: Survival rates for 1, 3, and 5 years after hepatic resection were 74%, 34%, and 9%, respectively, and those after transplantation were 60%, 32%, and 25%, respectively. Univariate analysis revealed that T-3, positive lymph nodes, positive surgical margins, and pTNM stage III and IV were statistically significant poor prognostic factors. Multivariate analysis revealed that pTNM stage 0, I, and II, negative lymph node, and negative surgical margins were statistically significant good prognostic factors. For the patients in pTNM stage 0-II with negative surgical margins, 1-, 3-, and 5-year survivals were 80%, 73%, and 73%, respectively. For patients in pTNM stage IV-A with negative lymph nodes and surgical margins, 1-, 3-, and 5- year survivals were 66%, 37%, and 37%, respectively. Conclusions: Satisfactory longterm survivals can be obtained by curative surgery for hilar cholangiocarcinoma either with hepatic resection or liver transplantation. Redefining pTNM stage III and IV-A is proposed to better define prognosis

Outcome analysis of 71 clinical intestinal transplantations

Objective: The aim of the study was to determine risk factors associated with graft failure and mortality after transplantation of the intestine alone or as pad of an organ complex. Summary Background Data: Even with modern immunosuppressive therapies, clinical intestinal transplantation remains a difficult and unreliable procedure. Causes for this and solutions are needed. Methods: Between May 1990 and February 1995, 71 intestinal transplantations were performed in 66 patients using tacrolimus and low-dose steroids. The first 63 patients, all but one treated 1 to 5 years ago, received either isolated grafts (n = 22), liver and intestinal grafts (n = 30), or multivisceral grafts (n = 11). Three mere recipients of allografts who recently underwent surgery and one undergoing retransplantation were given unaltered donor bone marrow cells perioperatively as a biologic adjuvant. Results: Of the first 63 recipients, 32 are alive: 28 have functioning primary grafts and 4 have resumed total parenteral nutrition after graft enterectomy. Thirty-five primary grafts were lost to technical and management errors (n = 10), rejection (n = 6), and infection (n = 19). Regression analysis revealed that duration of surgery, positive donor cytomegalovirus (CMV) serology, inclusion of graft colon, OKT3 use, steroid recycle, and high tacrolimus blood levels contributed to graft loss. All four intestine and bone marrow recipients are alive for 2-3 months without evidence of graft- versus-host disease. Conclusion: To improve outcome after intestinal transplantation with previous management protocols, it will be necessary to avoid predictably difficult patients, CMV seropositive donors, and inclusion of the graft colon. Bone marrow transplantation may further improve outcome by ameliorating the biologic barriers of rejection and infection and allowing less restrictive selection criteria

Comparison of various lazaroid compounds for protection against ischemic liver injury

Lazaroids are a group of 21-aminosteroids that lack steroid action but have a potent cytoprotective effect by inhibiting iron-dependent lipid peroxidation. However, there have been conflicting reports on the effectiveness and potency of the various lazaroid compounds. In this study, we compared the effectiveness of three major lazaroids on warm liver ischemia in dogs using a 2-hr hepatic vascular exclusion model. The agents were given to the animals intravenously for 30 min before ischemia. The animals were divided into 5 groups: Control (n=10), no treatment; Group F (n=6), U-74006F (10 mg/kg); Group G (n=6), U-74389G (10 mg/kg); Group A1 (n=6), U-74500A (10 mg/kg); Group A2 (n=6), U-74500A (5 mg/kg). The effect of treatment was evaluated by two-week animal survival, hepatic tissue blood flow, liver function tests, blood and tissue biochemistry, and histological analyses. Animal survival in all treated groups was significantly improved compared with the control (83-100% versus 30%). Elevation of liver enzymes after reperfusion was markedly attenuated in treated groups, except for an early significant increase in Group G. Postreperfusion hepatic tissue blood flow was much higher in all treated animals (50% of the preischemic level vs. 25% in the control). Lazaroids, particularly U-74500A at 5 mg/kg (Group A2), suppressed adenine nucleotide degradation during ischemia and enhanced the resynthesis of high-energy phosphates after reperfusion. Although structural abnormalities in postreperfusion liver tissues were markedly ameliorated in all treated groups, Group A2 showed significantly less neutrophil infiltration. Liver injury from warm ischemia and reperfusion was attenuated with all lazaroid compounds, of which U-74500A at 5 mg/kg exhibited the most significant protective activity

Hepatic resection and transplantation for peripheral cholangiocarcinoma

Background: Recent publications have questioned the role of orthotopic liver transplantation (OLT) in treating advanced or unresectable peripheral cholangiocarcinoma (Ch-Ca). Study Design: We reviewed our experience with Ch- Ca to determine survival rates, recurrence patterns, and risk factors in 54 patients who underwent either hepatic resection or OLT between 1981 and 1994. Liver transplantation was performed in patients with unresectable tumors (n = 12) and in those with advanced cirrhosis (n = 8). There were 33 women (61%) and 21 men (39%), with a mean age of 54.3 years. The median followup period was 6.8 years. Prognostic risk factors were analyzed by univariate and multivariate analyses. Results: Mortality within 30 days was 7.4%. Overall patient and tumor-free survival rates were 64% and 57% at 1 year, 34% and 34% at 3 years, and 26% and 27% at 5 years after operation. Thirty-two patients (59.3%) experienced tumor recurrence. Univariate analysis revealed that multiple tumors, bilobar tumor distribution, regional lymph node involvement, presence of metastasis, positive surgical margins, and advanced pTNM stages were significant negative predictors of both tumor-free and patient survival. Multivariate analysis revealed that positive margins, multiple tumors, and lymph node involvement were independently associated with poor prognosis. When patients with these three negative predictors were excluded, the patient survivals at 1, 3, and 5 years were 74%, 64%, and 62%, respectively. Conclusions: Both hepatic resection and OLT are effective therapies for Ch- Ca when the tumor can be removed with adequate margins, the lesion is singular, and lymph nodes are not involved

Oral yeasts and coliforms in HIV-infected patients in Hong Kong

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Liver resection for hilar and peripheral cholangiocarcinomas: A study of 62 cases

Objective: To analyze a single center's 14-year experience with 62 consecutive patients with hilar (HCCA) and peripheral (PCCA) cholangiocarcinomas. Summary Background Data: Long-term survival after surgical treatment of HCCA and PCCA has been poor. Methods: From March 1981 until December 1994, 62 consecutive patients with HCCA (n = 28) and PCCA (n = 34) underwent surgical treatment. The operations were individualized and included local excision of the tumor and suprapancreatic bile duct, lymph node dissection, vascular reconstruction, and subtotal hepatectomy. Clinical and pathologic risk factors were examined for prognostic influence. Results: Patients were followed for a median of 25 months (12-102 months). Postoperative morbidity and mortality (at 30 days) were 32% and 14%, respectively, for HCCA and 24% and 6% for PCCA. The survival rates for HCCA and PCCA were 79% (±8%) and 67% (±8%) at 1 year; 39% (±10%) and 40% (±9%) at 3 years; and 8% (±7%) and 35% (±10%) at 5 years, respectively. The median survival was 24 (±4) months for HCCA and 19 (±8) months for PCCA. The disease-free survival rates for HCCA and PCCA were 85% (±10%) and 77% (±9%) at 1 year; 18% (±11%) and 41% (±12%) at 3 years; and 18% (±11%) and 41% (±12%) at 5 years, respectively. Nearly 80% of these patients had TNM stage IV tumors. With HCCA, no risk factors were associated with patient survival. For PCCA, multiple tumors (relative risk [RR] = 3.5; 95% confidence interval [CI] = 1.2-10.5) and incomplete resection (RR = 8.3; 95% CI = 2.3- 29.6) were independently associated with a worse prognosis. For HCCA, there was a trend for lower disease-free survival in females (p = 0.056; log rank test). For PCCA, tumor size >5 cm was the only factor associated with disease recurrence (p = 0.024; log rank test). Conclusions: Even though rare, 5-year survival by resection can be achieved in both HCCA and PCCA, but new adjuvant treatments are clearly needed

Analysis of reaction and timing attacks against cryptosystems based on sparse parity-check codes

In this paper we study reaction and timing attacks against cryptosystems based on sparse parity-check codes, which encompass low-density parity-check (LDPC) codes and moderate-density parity-check (MDPC) codes. We show that the feasibility of these attacks is not strictly associated to the quasi-cyclic (QC) structure of the code but is related to the intrinsically probabilistic decoding of any sparse parity-check code. So, these attacks not only work against QC codes, but can be generalized to broader classes of codes. We provide a novel algorithm that, in the case of a QC code, allows recovering a larger amount of information than that retrievable through existing attacks and we use this algorithm to characterize new side-channel information leakages. We devise a theoretical model for the decoder that describes and justifies our results. Numerical simulations are provided that confirm the effectiveness of our approach