Figure Complexe De Rey

[Martha Vanschaick]

Lacotation et l'interprtation de la figure de Rey faisant consensus est la Boston Qualitative Scoring System (Systme de cotation qualitatif de Boston). Cette cotation est compose de 5 scores en fonction des capacits de planification, de fragmentation, d'organisation, de persvration ainsi que du soin et de la propret apports au dessin[6]. Grce cette cotation, la figure de Rey permet une bonne mesure des fonctions excutives[6].

Il existe des corrlations entre la ralisation de la figure de Rey et l'activation bilatrale du cortex temporo-parital, du lobe occipital et du lobe frontal droit[8]. La figure complexe de Rey-Osterrieth ncessite particulirement le cortex postro-temporo-parital soulignant le processus visuo-spatial dans la construction de la figure[8].

D'autres tudes ont prouv que le volume des matires blanche et grise des lobes paritaux tait un prdicteur de la russite de l'organisation de la copie de la figure complexe de Rey-Osterrieth alors que les matires blanche et grise des lobes frontaux tait un prdicteur de la russite dans la prcision de la copie de la figure complexe de Rey-Osterrieth[9]. Le volume de la matire grise du cortex frontal est en lien avec l'organisation et la prcision du dessin rappel de la figure complexe de Rey-Osterrieth[9].

The recent surge of interest in synthetic methodsin photochemistry has been driven by photoredox catalysis, a process in which a photocatalyst utilizes the energy of visible light to drive a reaction between two substrates which would not proceed otherwise (Ref 3,4). In many cases, the excited state of the photocatalyst can act as both an oxidant and reductant as needed, transferring or receiving an electron at the appropriate time (Figure 1). This is the general reaction scheme enabling the multitude of photoredox or metallophotoredox catalytic reactions driven by the ruthenium and iridium photocatalysts that have become prevalent over the last decade .

Differing from photoredox catalysis, photoactive electron donor-acceptor complexes do not require a photocatalyst (Figure 2). An electron donor (D) and an acceptor (A), which often do not absorb light individually, upon complexation can absorb visible light to undergo single-electron-transfer generating radical intermediates. This approach affords the opportunity to generate radicals (D+., A-.) from substrates which typically would not absorb in the visible spectrum. The challenge from the synthetic perspective is avoiding the back electron transferreaction, generating unproductively the two monomers in their ground state. The resurgence of electron-donor-acceptor synthetic methods as a field of photochemistry drew from two independent observations in 2013 by the Chatani group with photoredox (Ref 5) and the Melchiorre group studying organocatalysis (Ref 6). Control experiments for specific substrate combinations in the presence of light proceeded in the absence of catalyst.

The most straightforward approach to EDA complexes is the direct coupling of the two components upon light activation. In this approach, the viability of the reaction is intrinsic in the electron properties of the two partners and the resulting radicals. One common strategy involves a suitable leaving group within the electron donor-acceptor complex to initiate an irreversible fragmentation outcompeting back electron transfer (Figure 3A). The majority of examples in this class involve C-C bond formation with a few specialized examples for C-S bond formation (see table below).

A limitation of this approach is the requirement of highly polar donor and acceptor molecules which ultimately end up in the product. Alternately, a sacrificial donor can be used to form an EDA complex which upon excitation generates a radical intermediate suitable for reaction with a radical trap (Figure 3B). If the leaving group also can act as a redox auxiliary, then the synthetic scope of potential reactants can expand greatly (Figure 3C). Using the redox auxiliary allows for a suitably polar acceptor to form the EDA complex but generates a radical upon loss of the redox auxiliary that is not biased by internal stabilization or activation in molecule. Versatile redox auxiliaries that can be easily added and removed from desired reactants have the potential to allow synthetic platforms for broad use of the electron donor-acceptor EDA complexes.

To avoid the use of stoichiometric reagents, an important approach in this field incorporates the formation of the EDA complex into a catalytic cycle. In this approach, a catalyst activates one of the substrates (weakly polar) into a more polar form triggering the formation of the EDA complex which can then be photoactive. This mode of reactivity affords the possibility of asymmetric catalysis with a chiral catalyst. In this scheme a weak donor interacts with an organocatalyst.

Whether the EDA complex derives from a stoichiometric complex of a donor or acceptor or a more complicated catalytic cycle involving the formation of a pre-catalyst, this review demonstrates the synthetic utility of this exciting field.

The Rey Complex Figure Test (RCF) comprises a copy trial of the complex figure followed by one or more recall trials. Administration of the copy trial requires examinees to draw a copy of the figure that is presented on the table in front of them. The examinee is asked to reproduce the figure to the best of his or her ability; however, no rotation of the stimulus or measuring instruments is allowed. The most commonly used scoring system and normative data for the RCF were presented by Meyers and Meyers (1995). They use a copy, 3 min recall, 30 min recall, and a recognition trial. The manual says: After the respondent indicates he or she has completed the copy drawing, the stimulus figure and the drawing are immediately removed from view. (There is a 10 min limit on the time the respondent has to complete the drawing.) Three minutes of unrelated verbal activity follow. The...

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La reprsentation de Pierre dans les icnes du Petit-Palais, paris, par Raphalle Ziad, responsable du dpartement des arts byzantins. Vido extraite du livre numrique Pierre, une figure complexe

The electron transport chain (Figure 1) is the last component of aerobic respiration and is the only part of glucose metabolism that uses atmospheric oxygen. Oxygen continuously diffuses into plants; in animals, it enters the body through the respiratory system. Electron transport is a series of redox reactions that resemble a relay race or bucket brigade in that electrons are passed rapidly from one component to the next, to the endpoint of the chain where the electrons reduce molecular oxygen, producing water. There are four complexes composed of proteins, labeled I through IV in Figure 1, and the aggregation of these four complexes, together with associated mobile, accessory electron carriers, is called the electron transport chain. The electron transport chain is present in multiple copies in the inner mitochondrial membrane of eukaryotes and the plasma membrane of prokaryotes. Note, however, that the electron transport chain of prokaryotes may not require oxygen as some live in anaerobic conditions. The common feature of all electron transport chains is the presence of a proton pump to create a proton gradient across a membrane.

To start, two electrons are carried to the first complex aboard NADH. This complex, labeled I, is composed of flavin mononucleotide (FMN) and an iron-sulfur (Fe-S)-containing protein. FMN, which is derived from vitamin B2, also called riboflavin, is one of several prosthetic groups or co-factors in the electron transport chain. A prosthetic group is a non-protein molecule required for the activity of a protein. Prosthetic groups are organic or inorganic, non-peptide molecules bound to a protein that facilitate its function; prosthetic groups include co-enzymes, which are the prosthetic groups of enzymes. The enzyme in complex I is NADH dehydrogenase and is a very large protein, containing 45 amino acid chains. Complex I can pump four hydrogen ions across the membrane from the matrix into the intermembrane space, and it is in this way that the hydrogen ion gradient is established and maintained between the two compartments separated by the inner mitochondrial membrane.

Complex II directly receives FADH2, which does not pass through complex I. The compound connecting the first and second complexes to the third is ubiquinone (Q). The Q molecule is lipid soluble and freely moves through the hydrophobic core of the membrane. Once it is reduced, (QH2), ubiquinone delivers its electrons to the next complex in the electron transport chain. Q receives the electrons derived from NADH from complex I and the electrons derived from FADH2 from complex II, including succinate dehydrogenase. This enzyme and FADH2 form a small complex that delivers electrons directly to the electron transport chain, bypassing the first complex. Since these electrons bypass and thus do not energize the proton pump in the first complex, fewer ATP molecules are made from the FADH2 electrons. The number of ATP molecules ultimately obtained is directly proportional to the number of protons pumped across the inner mitochondrial membrane.

The third complex is composed of cytochrome b, another Fe-S protein, Rieske center (2Fe-2S center), and cytochrome c proteins; this complex is also called cytochrome oxidoreductase. Cytochrome proteins have a prosthetic group of heme. The heme molecule is similar to the heme in hemoglobin, but it carries electrons, not oxygen. As a result, the iron ion at its core is reduced and oxidized as it passes the electrons, fluctuating between different oxidation states: Fe++ (reduced) and Fe+++ (oxidized). The heme molecules in the cytochromes have slightly different characteristics due to the effects of the different proteins binding them, giving slightly different characteristics to each complex. Complex III pumps protons through the membrane and passes its electrons to cytochrome c for transport to the fourth complex of proteins and enzymes (cytochrome c is the acceptor of electrons from Q; however, whereas Q carries pairs of electrons, cytochrome c can accept only one at a time).

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