Origin of human motor readiness field linked to left middle frontal gyrus by MEG and PET

Combined magnetoencephalography and positron emission tomography identified a prior source of activity in the left middle frontal gyrus during uncued movements of the right index finger. Voluntary movements gave rise to a change in the cortical electrical potential known as the Bereitschaftspotential or Readiness Potential, recorded as early as 1500 ms before the onset of movement. The Readiness Field is the magnetic field counterpart to the Bereitschaftspotential. In the present study, magnetoencephalography identified four successively active sources of fluctuation in the Readiness Field in the period from 900 ms before, to 100 ms after, the onset of the movement. The first source to be active was registered between 900 and 200 ms prior to the onset of the movement. This source of initial activity was mapped by positron emission tomography to the middle frontal gyrus, Brodmann area 9. The three sources subsequently to be active were mapped to the supplementary motor area, premotor cortex, and motor cortex (M1), all in the left hemisphere.

Phenol and HCl at 550 degrees C yield a large variety of chlorinated toxic compounds

During the past decade it has been shown conclusively that the incineration of municipal and industrial wastes gives rise to emissions of chlorinated dibenzodioxins and dibenzofurans. However, the mechanism by which these toxic compounds are formed has not yet been fully established. Some researchers believe that the presence of organically bound chlorine is necessary, but others consider that inorganic forms of chlorine may also participate in the process. We now report the synthesis of a large number of chlorinated environmental pollutants in a simple high-temperature experiment. The results show that phenol and HCl are the most likely precursors of the chlorinated dibenzodioxins and dibenzofurans formed in the combustion of wastes. The dependence of the reaction on the concentration of HCl indicates a way of controlling the formation of these toxic compounds during incineration.

Stored wheat insect infestation related to uric acid as determined by liquid chromatography

Liquid chromatography is used to measure the uric acid content of wheat internally infested by various growth stages of granary weevil (Sitophilus granarius), rice weevil (Sitophilus oryzae), and lesser grain borer (Ryzopertha dominica). Good correlation exists between numbers of insects and uric acid content of grain infested by a given stage of an internally infesting stored product insect, with correlation coefficients ranging from 0.970 to 0.998. Uric acid content of infested grain increases as the insect life cycle progresses, with granary weevil producing the greatest quantities of uric acid followed in order by rice weevil and lesser grain borer. A detection limit for the analytical procedure of less than 1.0 ppm uric acid allows detection of infestation levels as low as one kernel per 100 g grain for late instar granary weevil larvae. This limit is sufficiently sensitive to detect levels of infestation that may be commonly encountered in commerce.