نتایج جستجو برای: log rank test
تعداد نتایج: 932838 فیلتر نتایج به سال:
Two-sample weighted log-rank statistics are used in the presence of right censoring to test whether failure times from two populations have diierent survival distributions. Kosorok (1998a) showed that large families of these statistics form stochastic processes indexed by weight functions and that these function-indexed statistics can be used to construct versatile test procedures simultaneousl...
A preliminary study has linked raised blast glutathione levels with chemoresistance in acute myeloid and lymphoblastic leukemia in adults and children. In this study, therefore, the relationship between leukemic blast glutathione levels and prognosis in childhood acute lymphoblastic leukemia (ALL) was investigated. A total of 77 childhood ALL samples were analyzed, 62 at initial presentation an...
A wide pulse pressure (PP) is a marker of increased artery stiffness and high cardiovascular (CV) risk. To investigate the prognostic value of ambulatory PP, which is currently unknown, we studied 2010 initially untreated subjects with uncomplicated essential hypertension (mean age, 51.7 years; 52% men). All subjects underwent baseline procedures including 24-hour noninvasive ambulatory blood p...
A completion of an m-by-n matrix A with entries in {0, 1, ∗} is obtained by setting all ∗-entries to constants 0 or 1. A system of semi-linear equations over GF2 has the form Mx = f(x), where M is a completion of A and f : {0, 1}n → {0, 1}m is an operator, the ith coordinate of which can only depend on variables corresponding to ∗-entries in the ith row of A. We conjecture that no such system c...
Matrices of low rank are pervasive in big data, appearing in recommender systems, movie preferences, topic models, medical records, and genomics. While there is a vast literature on how to exploit low rank structure in these datasets, there is less attention on explaining why the low rank structure appears in the first place. We explain the abundance of low rank matrices in big data by proving ...
Glioblastoma (GBM) is the most common and aggressive primary brain tumor. The identification of novel molecular prognostic markers of GBM has recently been an area of great interest in neuro-oncology. The methylation status of the MGMT gene promoter is currently a promising molecular prognostic marker, but some controversial data have precluded its clinical use. We analyzed MGMT methylation by ...
We examine n×nmatrices over Zm, with 0’s in the diagonal and nonzeros elsewhere. If m is a prime, then such matrices have large rank (i.e., n1/(p−1) − O(1) ). If m is a non-prime-power integer, then we show that their rank can be much smaller. For m = 6 we construct a matrix of rank exp(c √ log n log log n). We also show, that explicit constructions of such low rank matrices imply explicit cons...
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