Non-Simply-Connected Gauge Groups and Rational Points on Elliptic Curves

We consider the F-theory description of non-simply-connected gauge groups appearing in the E8 x E8 heterotic string. The analysis is closely tied to the arithmetic of torsion points on an elliptic curve. The general form of the corresponding elliptic fibration is given for all finite subgroups of E8 which are applicable in this context. We also study the closely-related question of point-like instantons on a K3 surface whose holonomy is a finite group. As an example we consider the case of the heterotic string on a K3 surface having the E8 gauge symmetry broken to (E6 x SU(3))/Z3 or SU(9)/Z3 by point-like instantons with Z3 holonomy.Comment: 15 pages, 2 embedded figures, some spurious U(1)'s remove

Cancers of unknown primary diagnosed during hospitalization: a population-based study

Background: Cancers of Unknown Primary (CUP) are the 3-4th most common causes of cancer death and recent clinical guidelines recommend that patients should be directed to a team dedicated to their care. Our aim was to inform the care of patients diagnosed with CUP during hospital admission. Methods: Descriptive study using hospital admissions (Scottish Morbidity Record 01) linked to cancer registrations (ICD-10 C77-80) and death records from 1998 to 2011 in West of Scotland, UK (population 2.4 m). Cox proportional hazards models were used to assess effects of baseline variables on survival. Results: Seven thousand five hundred ninety nine patients were diagnosed with CUP over the study period, 54.4% female, 67.4% aged ≥ 70 years, 36.7% from the most deprived socio-economic quintile. 71% of all diagnoses were made during a hospital admission, among which 88.6% were emergency presentations and the majority (56.3%) were admitted to general medicine. Median length of stay was 15 days and median survival after admission 33 days. Non-specific morphology, emergency admission, age over 60 years, male sex and admission to geriatric medicine were all associated with poorer survival in adjusted analysis. Conclusions: Patients with a diagnosis of CUP are usually diagnosed during unplanned hospital admissions and have very poor survival. To ensure that patients with CUP are quickly identified and directed to optimal care, increased surveillance and rapid referral pathways will be required

Validation of a modified clinical risk score to predict cancer-specific survival for stage II colon cancer

Many patients with stage II colon cancer will die of their disease despite curative surgery. Therefore, identification of patients at high risk of poor outcome after surgery for stage II colon cancer is desirable. This study aims to validate a clinical risk score to predict cancer-specific survival in patients undergoing surgery for stage II colon cancer. Patients undergoing surgery for stage II colon cancer in 16 hospitals in the West of Scotland between 2001 and 2004 were identified from a prospectively maintained regional clinical audit database. Overall and cancer-specific survival rates up to 5 years were calculated. A total of 871 patients were included. At 5 years, cancer-specific survival was 81.9% and overall survival was 65.6%. On multivariate analysis, age ≥75 years (hazard ratio (HR) 2.11, 95% confidence intervals (CI) 1.57–2.85; P<0.001) and emergency presentation (HR 1.97, 95% CI 1.43–2.70; P<0.001) were independently associated with cancer-specific survival. Age and mode of presentation HRs were added to form a clinical risk score of 0–2. The cancer-specific survival at 5 years for patients with a cumulative score 0 was 88.7%, 1 was 78.2% and 2 was 65.9%. These results validate a modified simple clinical risk score for patients undergoing surgery for stage II colon cancer. The combination of these two universally documented clinical factors provides a solid foundation for the examination of the impact of additional clinicopathological and treatment factors on overall and cancer-specific survival

Design improvement of a pump wear ring labyrinth seal

The investigation was successful in obtaining two improved designs for the impeller wear ring seal of the liquid hydrogen turbopump of interest. A finite difference computer code was extensively used in a parametric computational study in determining a cavity configuration with high flow resistance due to turbulence dissipation. These two designs, along with that currently used, were fabricated and tested. The improved designs were denoted Type O and Type S. The measurements showed that Type O and Type S given 67 and 30 percent reduction in leakage over the current design, respectively. It was found that the number of cavities, the step height and the presence of a small stator groove are quite important design features. Also, the tooth thickness is of some significance. Finally, the tooth height and an additional large cavity cut out from the stator (upstream of the step) are of negligible importance

Risk of critical illness among patients with solid cancers: a population-based observational study of 118,541 adults

Importance: Critical illness may be a potential determinant of cancer outcomes and geographic variations, but its role has not been described before. Objective: To determine the incidence of admission to intensive care units (ICUs) within 2 years following cancer diagnosis. Design, Setting, and Participants: This was a retrospective observational study using cancer registry data in 4 datasets from 2000 to 2009 with linked ICU admission data from 2000 to 2011, in the West of Scotland region of the United Kingdom (population, 2.4 million; all 16 ICUs within the region). All 118 541 patients (≥16 years) diagnosed as having solid (nonhematological) cancers. Their median age was 69 years, and 52.0% were women. Main Outcomes and Measures: Demographic and clinical variables associated with admission to an ICU and death in an ICU. Results: A total of 118 541 patients met the study criteria. Overall, 6116 patients (5.2% [95% CI, 5.0%-5.3%]) developed a critical illness and were admitted to an ICU within 2 years. Risk of critical illness was highest at ages 60 to 69 years and higher in men. The cumulative incidence of critical illness was greatest for small intestinal (17.2% [95% CI, 13.3%-21.8%]) and colorectal cancers (16.5% [95% CI, 15.9%-17.1%]). The risk following breast cancer was low (0.8% [95% CI, 0.7%-1.0%]). The percentage who died in ICUs was 14.1% (95% CI, 13.3%-15.0%), and during the hospital stay, 24.6% (95% CI, 23.5%-25.7%). Mortality was greatest among emergency medical admissions and lowest among elective surgical patients. The risk of critical illness did not vary by socioeconomic circumstances, but mortality was higher among patients from deprived areas. Conclusions and Relevance: In this study, about 1 in 20 patients experienced a critical illness resulting in ICU admission within 2 years of cancer diagnosis. The associated high mortality rate may make a significant contribution to overall cancer outcomes