GavaldB, R. and J.L. BalcBzar, Strong and robustly strong polynomial time reducibilities to sparse sets, Theoretical Computer Science 88 (1991) I-14. Reducibility defined by oracle strong nondeterministic machines is studied. Two definitions of relativized strength are presented and separated. The corresponding reduction classes of the sparse sets give two nonuniform analogs of the class NPncoN...

We present a new technique, inspired by zero-knowledge proof systems, for proving lower bounds on approximating the chromatic number of a graph. To illustrate this technique we present simple reductions from max-3-coloring and max-3-sat, showing that it is hard to approximate the chromatic number within (N), for some > 0. We then apply our technique in conjunction with the probabilistically che...

Long-term airborne lead exposure, even below official occupational limits, has been found to cause lead poisoning at higher frequencies than expected, which suggests that China's existing occupational exposure limits should be reexamined. A retrospective cohort study was conducted on 1832 smelting workers from 1988 to 2008 in China. These were individuals who entered the plant and came into con...

We present a new technique, inspired by zero-knowledge proof systems, for proving lower bounds on approximating the chromatic number of a graph. To illustrate this technique we present simple reductions from max-3-coloring and max-3-sat, showing that it is hard to approximate the chromatic number within (N), for some > 0. We then apply our technique in conjunction with the probabilistically che...

The objective was to study the evaluation of serum transferrin receptor (sTfR) for Fe deficiency in women of child-bearing age. Primary screening was performed in 942 women ranging in child-bearing age. Serum ferritin (SF), Zn protoporphyrin (ZPP) and Hb were determined. Then the subjects were divided into four groups: normal, Fe store depletion (IDs), Fe-deficiency erythropoiesis and Fe-defici...

BACKGROUND Iron deficiency is common in early childhood and has been associated with developmental delay. It is not known how reliably markers of iron deficiency identify true iron deficiency, defined as a therapeutic response to oral iron. METHODS The subjects were members of the Millennium Baby Study cohort. At age 13 months a venous blood sample was taken for mean cell volume (MCV), haemog...

We address the issue of inapproximability of the wavelength assignment problem in wavelength division multiplexing (WDM) optical networks. We prove that in an n-node WDM optical network with m lightpaths and maximum load L, if NP = ZPP, for any constant δ > 0, no polynomial time algorithm can achieve approximation ratio n1/2−δ or m1−δ , where NP is the class of problems which can be solved by n...

In a cross sectional study of occupational exposure to inorganic lead 91 men performed a series of microcomputer based tasks assessing sensor motor reaction time, memory, attention, verbal reasoning, and spatial processing. Performance on the tasks was studied in relation to three ranges of blood lead concentration (low, less than 20 micrograms/dl; medium, 21-40 micrograms/dl; and high, 41-80 m...

Anemia that accompanies lead poisoning is in part the result of various inhibitory effects of lead on heme biosynthesis. Lead also increases the rate of red blood cell destruction due to the profoundly depressed activities of erythrocyte pyrimidine 5'-nucleotidase (P5N) activities. We studied parameters of the two metabolic pathways in the workers exposed to lead to evaluate P5N in the lead exp...