432 research outputs found
Specht modules and semisimplicity criteria for Brauer and Birman--Murakami--Wenzl Algebras
A construction of bases for cell modules of the Birman--Murakami--Wenzl (or
B--M--W) algebra by lifting bases for cell modules of
is given. By iterating this procedure, we produce cellular bases for B--M--W
algebras on which a large abelian subalgebra, generated by elements which
generalise the Jucys--Murphy elements from the representation theory of the
Iwahori--Hecke algebra of the symmetric group, acts triangularly. The
triangular action of this abelian subalgebra is used to provide explicit
criteria, in terms of the defining parameters and , for B--M--W algebras
to be semisimple. The aforementioned constructions provide generalisations, to
the algebras under consideration here, of certain results from the Specht
module theory of the Iwahori--Hecke algebra of the symmetric group
Young-Onset Colorectal Cancer: Earlier Diagnoses or Increasing Disease Burden?
Colorectal cancer (CRC) incidence and mortality in the United States have changed strikingly in recent decades. Overall, CRC incidence decreased by >30% from 1975 (59.5 per 100,000) to 2013 (37.9 per 100,000). CRC mortality similarly declined from 28.1 per 100,000 in 1975 to 14.5 per 100,000 in 2013—nearly a 50% decrease.1 Screen-eligible populations, particularly those over age 65, have experienced the largest declines in incidence and mortality
Hecke algebras of finite type are cellular
Let \cH be the one-parameter Hecke algebra associated to a finite Weyl
group , defined over a ground ring in which ``bad'' primes for are
invertible. Using deep properties of the Kazhdan--Lusztig basis of \cH and
Lusztig's \ba-function, we show that \cH has a natural cellular structure
in the sense of Graham and Lehrer. Thus, we obtain a general theory of ``Specht
modules'' for Hecke algebras of finite type. Previously, a general cellular
structure was only known to exist in types and .Comment: 14 pages; added reference
Racial Disparities in Incidence of Young-Onset Colorectal Cancer and Patient Survival
Background & Aims: Increasing rates of young-onset colorectal cancer (CRC) have attracted substantial research and media attention, but we know little about racial disparities among younger adults with CRC. We examined racial disparities in young-onset CRC by comparing CRC incidence and relative survival among younger (<50-year-old) adults in 2 time periods. Methods: Using data from the Surveillance, Epidemiology, and End Results program of cancer registries, we estimated CRC incidence rates (per 100,000 persons 20–49 years old) from 1992 through 2014 for different periods (1992–1996 vs 2010–2014) and races (white vs black). Relative survival was calculated as the ratio of observed survival to expected survival in a comparable cancer-free population. Results: From 1992–1996 to 2010–2014, CRC incidence increased from 7.5 to 11.0 per 100,000 in white individuals and from 11.7 to 12.7 per 100,000 in black individuals. The increase in rectal cancer was larger in whites (from 2.7 to 4.5 per 100,000) than in blacks (from 3.4 to 4.0 per 100,000); in the 2010–2014 period, blacks and whites had similar rates of rectal cancer. Compared with whites, blacks had smaller increases in relative survival with proximal colon cancer but larger increases in survival with rectal cancer (from 55.3% to 70.8%). Conclusion: In an analysis of the Surveillance, Epidemiology, and End Results database, we found racial disparities in incidence of young-onset CRC and patient survival for cancer of the colon but minimal difference for rectal cancer. Well-documented and recent increases in young-onset CRC have largely been due to increases in rectal cancer, especially in whites
Decrease in Incidence of Young-Onset Colorectal Cancer Before Recent Increase
The increasing incidence of colorectal cancer in younger adults (aged <50 years) has been widely reported. Using data from the Surveillance, Epidemiology, and End Results Program, we found young-onset colorectal cancer incidence rates decreased from 1975 through about 1990. Decreases were more prominent in the colon, a contrast with more recent increases in rectal cancer. Incidence rates subsequently increased, differing by time period and 5-year age group. This inflection point is consistent with a birth cohort effect and points to early life exposures—accumulated throughout the life course—that may increase cancer risk. Studying early life exposures among persons born after 1960 may advance our understanding of colorectal cancer in younger adults
The Point of Origin of the Radio Radiation from the Unresolved Cores of Radio-Loud Quasars
Locating the exact point of origin of the core radiation in active galactic
nuclei (AGN) would represent important progress in our understanding of
physical processes in the central engine of these objects. However, due to our
inability to resolve the region containing both the central compact object and
the jet base, this has so far been difficult. Here, using an analysis in which
the lack of resolution does not play a significant role, we demonstrate that it
may be impossible even in most radio loud sources for more than a small
percentage of the core radiation at radio wavelengths to come from the jet
base. We find for 3C279 that percent of the core flux at 15 GHz must
come from a separate, reasonably stable, region that is not part of the jet
base, and that then likely radiates at least quasi-isotropically and is
centered on the black hole. The long-term stability of this component also
suggests that it may originate in a region that extends over many Schwarzschild
radii.Comment: 7 pages with 3 figures, accepted for publication in Astrophysics and
Space Scienc
Patterns of Sociodemographic and Clinicopathologic Characteristics of Stages II and III Colorectal Cancer Patients by Age: Examining Potential Mechanisms of Young-Onset Disease
Background and Aims. As a first step toward understanding the increasing incidence of colorectal cancer (CRC) in younger (age < 50) populations, we examined demographic, clinicopathologic, and socioeconomic characteristics and treatment receipt in a population-based sample of patients newly diagnosed with stages II and III CRC. Methods. Patients were sampled from the National Cancer Institute's Patterns of Care studies in 1990/91, 1995, 2000, 2005, and 2010 (n=6,862). Tumor characteristics and treatment data were obtained through medical record review and physician verification. We compared sociodemographic and clinicopathologic characteristics and treatment patterns of younger (age < 50) and older (age 50-69, age ≥ 70) CRC patients. Results. Younger patients were more likely to be black (13%) and Hispanic (15%) than patients aged 50-69 years (11% and 10%, resp.) and ≥70 years (7% each). A larger proportion of young white (41%) and Hispanic (33%) patients had rectal tumors, whereas tumors in the right colon were the most common in young black patients (39%). The majority of younger patients received chemotherapy and radiation therapy, although receipt of microsatellite instability testing was suboptimal (27%). Conclusion. Characteristics of patients diagnosed with young-onset CRC differ considerably by race/ethnicity, with a higher proportion of black and Hispanic patients diagnosed at the age of < 50 years
Learning Behavioural Context
The original publication is available at www.springerlink.co
A preliminary study of human amniotic membrane as a potential chondrocyte carrier
Purpose: To investigate the feasibility of using processed human amniotic membrane (HAM) to support the attachment and proliferation of chondrocytes in vitro which in turn can be utilised as a cell delivery vehicle in tissue engineering applications. Methods: Fresh HAM obtained from patients undergoing routine elective caesarean sections was harvested, processed and dried using either freeze drying (FD) or air drying (AD) methods prior to sterilisation by gamma irradiation. Isolated, processed and characterised rabbit autologous chondrocytes were seeded on processed HAM and cultured for up to three weeks. Cell attachment and proliferation were examined qualitatively using inverted brightfield microscopy. Results: Processed HAM appeared to allow cell attachment when implanted with chondrocytes. Although cells seeded on AD and FD HAM did not appear to attach as strongly as those seeded on glycerol preserved intact human amniotic membrane, these cells to be proliferated in cell culture conditions. Conclusion: Preliminary results show that processed HAM promotes chondrocyte attachment and proliferation
RE: Colorectal Cancer Incidence Patterns in the United States, 1974–2013
In the latest issue of the Journal, Siegel et al. report that young adults born around 1990 (and so currently age 20 to 29 years) have double and quadruple the risk of colon and rectal cancer (CRC), respectively, compared with the same age group born in 1950. We believe presenting relative increases in incidence isolated from the absolute risk of CRC in younger adults can be misleading. Using relative or ratio measures to communicate risk of young-onset CRC may lead the casual reader or popular press to misinterpret the extent to which incidence is increasing
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