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The stopping cross sections of several substances were measured for protons in the energy range 50 to 600 kev. The substances investigated were lithium, beryllium, copper, gold, lead, lithium fluoride and calcium fluoride. The energy loss in the substance under investigation was determined by measuring the incident proton beam energy necessary for a given outgoing energy before and after a thin evaporated layer of the substance had been placed in the path of the beam. The areal density of the layer was accurately determined by one of two methods: A chemical analysis or a micro-balance weighing of a known area of the evaporated deposit. The same layer was used in the energy loss as in the density determinations. These absolute measurements were made near 350 kev. Relative energy loss measurements were made over the remainder of the range, and normalized to them. The apparatus was so designed that the evaporations, weighings and energy loss determinations could be performed without removing the substance from the vacuum.

The stopping cross sections of several substances were measured for protons in the energy range 50 to 600 kev. The substances investigated were lithium, beryllium, copper, gold, lead, lithium fluoride and calcium fluoride. The energy loss in the substance under investigation was determined by measuring the incident proton beam energy necessary for a given outgoing energy before and after a thin evaporated layer of the substance had been placed in the path of the beam. The areal density of the layer was accurately determined by one of two methods: A chemical analysis or a micro-balance weighing of a known area of the evaporated deposit. The same layer was used in the energy loss as in the density determinations. These absolute measurements were made near 350 kev. Relative energy loss measurements were made over the remainder of the range, and normalized to them. The apparatus was so designed that the evaporations, weighings and energy loss determinations could be performed without removing the substance from the vacuum.

Historical references to the emergence of the current concept of ADHD typically cite descriptions from medical textbooks by Weikard (1775) and Crichton (An inquiry into the nature and origin of mental derangement: Comprehending a concise system of the physiology and pathology of the human mind and a history of the passion and their affects. Cardell Jr and Davies, Londres, 1798) on attention disorders, poems of Hoffman on hyperactive and impulsive behaviors (Der Struwwelpeter. Frankfurt am Main, Literarische Anstalt, 1843), as well as the work of Still (Lancet 1:1008-1012, 1077-1082, 1163-1168, 1902a, Lancet 159(4102):1008-1013, 1902b, Lancet 159(4103):1077-1082, 1902c, Lancet 159(4104):1163-1168, 1902d) on impulsive behaviors and defective moral regulation of behavior. The notion of "instability” developed by French physicians between 1887 and 1910 is rarely mentioned and often ignored. Writings from this period show that in France, the emergence of the concept of ADHD according to modern terminology comes from the notion of "mental instability” introduced in the 1890s under the leadership of Désiré-Magloire Bourneville at the Hospital Bicêtre in Paris, based on his observations of children and adolescents who had been labeled "abnormal” and placed in medical and educational institutions. In the early twentieth century, elaborating on the observations of Bourneville, Jean Phillipe and Georges Paul-Boncour showed the presence of a subgroup of "unstable” children who suffered from a disease entity in its own right within the population of "abnormal” schoolchildren (the terminology of the time). This new pathological entity included symptoms of hyperactivity, impulsivity and inattention, corresponding to today's classic triad of ADHD symptoms. While noting the lack of behavioral inhibition, clinical descriptions of Bourneville, Philip and Paul-Boncour also considered the notion of "moral disorder” which at that time played an important role in psychopathology. This res

Impaired decision making and Working Memory (WM) are among the characteristic symptoms of patients affected by Attention Deficit/Hyperactivity Disorder (ADHD). In order to investigate whether a WM training can affect the attitude towards risky decision making, we designed a study where participants had to perform a Probabilistic Gambling Task. Our study has demonstrated that WM training affects in a different way controls and ADHD patients, who showed an increased tendency towards a risk-taking attitude in case of the adaptive variant of the memory task. In ADHD patients, the frontal sites appeared the most affected, whereas global brain activity was likely to be affected in controls. This study shows also the benefits of cognitive training in ADHD patients, but in healthy subjects too.