431 research outputs found
A Gyrochronology and Microvariability Survey of the Milky Way's Older Stars Using Kepler's Two-Wheels Program
Even with the diminished precision possible with only two reaction wheels,
the Kepler spacecraft can obtain mmag level, time-resolved photometry of tens
of thousands of sources. The presence of such a rich, large data set could be
transformative for stellar astronomy. In this white paper, we discuss how
rotation periods for a large ensemble of single and binary main- sequence
dwarfs can yield a quantitative understanding of the evolution of stellar
spin-down over time. This will allow us to calibrate rotation-based ages beyond
~1 Gyr, which is the oldest benchmark that exists today apart from the Sun.
Measurement of rotation periods of M dwarfs past the fully-convective boundary
will enable extension of gyrochronology to the end of the stellar
main-sequence, yielding precise ages ({\sigma} ~10%) for the vast majority of
nearby stars. It will also help set constraints on the angular momentum
evolution and magnetic field generation in these stars. Our Kepler-based study
would be supported by a suite of ongoing and future ground-based observations.
Finally, we briefly discuss two ancillary science cases, detection of
long-period low-mass eclipsing binaries and microvariability in white dwarfs
and hot subdwarf B stars that the Kepler Two-Wheels Program would facilitate.Comment: Kepler white pape
Plan, execute, and discuss vibration measurements and correlations to evaluate a NASTRAN finite element model of the AH-64 helicopter airframe
A ground vibration test was performed on the AH-64 (Apache) helicopter to determine the frequency response of the airframe. The structure was excited at both the main and tail rotor hubs, separately, and response measurements were taken at 102 locations throughout the fuselage structure. Frequency responses were compared and correlated with results from a NASTRAN finite element model of AH-64. In addition, natural frequencies and mode shapes were estimated from the frequency response data and were correlated with analytical results
PRE-binding sites in the MDR of CLL: Potential Tumor Suppressor Regulation
Chronic lymphocytic leukemia [CLL] is the most common adult leukemia and is heterogeneous in clinical presentation. CLL cases present with various chromosomal aberrations, including 11q23, 14q32, 17p, and trisomy 12, with the most common abnormality being deletion of 13q14 [1]. Although monoallelic deletion of 13q14 is common, there is a subset of patients who have complete nullisomy at 13q14, a locus that has been hypothesized to contribute to CLL pa thogenesis [2] due to loss of tumor suppressors [DLEU and miR-15a/16-1].We hypothesized that deletion of both copies of 13q14 would lead to uncontrollable proliferation of CLL cells and a poor prognosis. We examined our 13q14 nullisomy for survival, treatment-free survival, lymphocyte doubling time, and the presence of lymphadenopathy. Furthermore, we compared the gene expression profiles between patients with 13q14 monosomy, nullisomy, or normal karyotype. Our results suggest that patients with 13q nullisomy have a higher incidence of bulky lymphadenopathy [16.6% compared to 10% of monosomy patients], a higher frequency of lymphocyte doubling time [27.7% compared to 7.4% of monosomy patients], and a higher rate of needing treatment [50% compared to 18.5% of monosomy patients]. We observed deletion of DLEU1 and HTR2A, consistent with a gene dosage effect, and observed PRE-binding sites on DLEU1. Patients with homozygous deletion of 13q14 had a worse prognosis compared to heterozygotes. Lastly, the DLEU1 locus is a possible âsecond hitâ loss for CLL progression
Agricultural Pesticide Use and Risk of t(14;18)-Defined Subtypes of Non-Hodgkin Lymphoma
Pesticides have been specifically associated with the t(14;18)(q32;q21) chromosomal translocation. To investigate whether the association between pesticides and risk of non-Hodgkin lymphoma (NHL) differs for molecular subtypes of NHL defined by t(14; 18) status, we obtained 175 tumor blocks from case subjects in a population-based case-control study conducted in Nebraska between 1983 and 1986. The t(14;18) was determined by interphase fluorescence in situ hybridization in 172 of 175 tumor blocks. We compared exposures to insecticides, herbicides, fungicides, and fumigants in 65 t(14;18)-positive and 107 t(14;18)-negative case subjects with those among 1432 control subjects. Multivariate polytomous logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs). Compared with farmers who never used pesticides, the risk of t(14;18)-positive NHL was significantly elevated among farmers who used animal insecticides (OR = 2.6; 95%CI, 1.0-6.9), crop insecticides (OR = 3.0; 95% CI, 1.1-8.2), herbicides (OR = 2.9; 95% CI, 1.1-7.9), and fumigants (OR = 5.0; 95% CI, 1.7-14.5). None of these pesticides were associated with t(14;18)-negative NHL. The risk of t(14;18)-positive NHL associated with insecticides and herbicides increased with longer duration of use. We conclude that insecticides, herbicides, and fumigants were associated with risk of t(14;18)-positive NHL but not t(14;18)-negative NHL. These results suggest that defining subsets of NHL according to t(14;18) status is a useful approach for etiologic research. (Blood. 2006; 108:1363-1369
Pesticide Product Use and Risk of Non-Hodgkin Lymphoma in Women
A population-based, incidence caseâcontrol study was conducted among women in upstate New York to determine whether pesticide exposure is associated with an increase in risk of non-Hodgkin lymphoma (NHL) among women. The study involved 376 cases of NHL identified through the State Cancer Registry and 463 controls selected from the Medicare beneficiary files and state driverâs license records. Information about history of farm work, history of other jobs associated with pesticide exposure, use of common household pesticide products, and potential confounding variables was obtained by telephone interview. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using an unconditional logistic regression model. The risk of NHL was doubled (OR = 2.12; 95% CI, 1.21â3.71) among women who worked for at least 10 years at a farm where pesticides were reportedly used. When both farming and other types of jobs associated with pesticide exposure were combined, there was a progressive increase in risk of NHL with increasing duration of such work (p = 0.005). Overall cumulative frequency of use of household pesticide products was positively associated with risk of NHL (p = 0.004), which was most pronounced when they were applied by subjects themselves. When exposure was analyzed by type of products used, a significant association was observed for mothballs. The associations with both occupational and household pesticides were particularly elevated if exposure started in 1950â1969 and for high-grade NHL. Although the results of this caseâcontrol study suggest that exposure to pesticide products may be associated with an increased risk of NHL among women, methodologic limitations related to selection and recall bias suggest caution in inferring causation
Long-Term Outcomes of Autologous Stem Cell Transplantation for Follicular Non-Hodgkin Lymphoma: Effect of Histological Grade and Follicular International Prognostic Index
AbstractAlthough results of autologous stem cell transplantation (SCT) for recurrent follicular non-Hodgkin lymphoma (NHL) have been previously reported, the long-term results and evaluation of prognostic factors in a large patient population receiving this therapy are difficult to find in the literature. To address these issues, we evaluated 248 patients with recurrent follicular NHL treated with high-dose chemotherapy and autologous SCT between 7/87 and 6/03. According to the World Health Organization (WHO) classification system, 64 patients (26%) had follicular NHL grade 1 (FL 1), 98 (40%) had FL 2, and 86 (35%) had FL 3. At the time of transplantation, 88 of the patients (35%) had a Follicular Lymphoma International Prognostic Index (FLIPI) score of low risk, 87 (35%) had an intermediate-risk FLIPI score, 37 (15%) had a high-risk FLIPI score, and 36 (15%) had at least 1 missing value, preventing calculation of the FLIPI score. The 5-year overall survival (OS) for all patients was 63%, and the 5-year progression-free survival (PFS) was 44%. In a multivariate analysis, a histological grade of FL 3, a high-risk FLIPI score at the time of transplantation, and having received 3 or more previous chemotherapy regimens were significant factors for predicting a worse OS. In addition, the use of a transplantation regimen including a monoclonal antibody decreased the relative risk of progressive lymphoma. These data suggest that transplantation earlier in the course of the disease for patients with follicular lymphoma with use of a monoclonal antibodyâbased regimen may lead to improved outcomes
Autologous hematopoietic stem cell transplantation for mantle cell lymphoma
AbstractThis study evaluated the outcomes of patients who underwent high-dose chemotherapy (HDC) and autologous hematopoietic stem cell transplantation (autoHSCT) for mantle cell non-Hodgkin's lymphoma and the effect of clinical and treatment characteristics. The clinical outcome and prognostic factors in 40 patients who underwent HDC and autoHSCT for mantle cell lymphoma between June 1991 and August 1998 were analyzed. With a median follow-up of 24 months for the surviving patients (range, 4-68 months), the 2-year overall survival was 65% and the 2-year event-free survival (EFS) was 36%. In univariate analysis, characteristics predictive of a poor EFS were blastic morphology (P = .019) and the patient having received 3 or more prior chemotherapy regimens (P = .004). In a multivariate analysis, the only factor associated with a poor EFS was the number of prior chemotherapy regimens. Those patients who received 3 or more prior therapies had a 2-year EFS of 0%, and those who received <3 therapies had a 2-year EFS of 45% (P = .004). Patients with mantle cell lymphoma can obtain prolonged EFS with HDC and autoHSCT; however, this strategy for prolonged EFS appears to work optimally in patients who are less heavily pretreated. Whether this therapy will increase the overall survival or EFS in patients receiving transplants in first complete remission will need to be tested in prospective randomized clinical trials.Biol Blood Marrow Transplant 2000;6(6):640-5
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