نتایج جستجو برای: 13n
تعداد نتایج: 345 فیلتر نتایج به سال:
For a given undirected graph G with n vertices and m edges, we present an approximation algorithm for the minimum vertex cover problem. Our algorithm nds a vertex cover within 2 8m 13n 2 +8m of the optimal size in O(nm) time.
BACKGROUND Metabolic imaging with positron emission tomography (PET) can detect tissue viability in clinical infarct regions. With appropriate tracer kinetic models and serial PET imaging, regional myocardial blood flow and rates of metabolism can now be quantified in patients with recent myocardial infarctions. METHODS AND RESULTS Serial PET imaging with [13N]ammonia, [11C]acetate, and 18F-d...
OBJECTIVE To elucidate the radionuclides and radiochemical impurities included in radiosynthesis processes of positron emission tomography (PET) tracers. METHODS Target materials and PET tracers were produced using a cyclotron/synthesis system from Sumitomo Heavy Industry. Positron and γ-ray emitting radionuclides were quantified by measuring radioactivity decay and using the high-purity Ge d...
Problem A1 We call a finite set of positive integers feasible if every member of S has the form 23, and no member of S divides any other member of S. We call a positive integer n feasible if n = ∑ S for some feasible set S. We are required to show that every positive integer is feasible. If not, then there exists a smallest infeasible number n. If n is even, say n = 2k for some positive integer...
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