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See detailDissociation of increases in plasma insulin-like growth factor I and testosterone during the onset of puberty in bulls
Renaville, Robert ULiege; Massart, Serge; Sneyers, M. et al

in Journal of Reproduction and Fertility (1996), 106(1), 79-86

The present study was conducted to examine the relationship between plasma concentrations of testosterone, insulin-like growth factor I (IGF-I) and IGF-binding proteins (IGFBPs) during puberty, in male ... [more ▼]

The present study was conducted to examine the relationship between plasma concentrations of testosterone, insulin-like growth factor I (IGF-I) and IGF-binding proteins (IGFBPs) during puberty, in male calves treated with GnRH or testosterone propionate. Twelve male Holstein calves (10 weeks old) were assigned to the control group (n = 6), the GnRH-treated group (n = 3) or the testosterone-treated group (n = 3). For 8 weeks, the GnRH-treated group received a single i.v. injection of GnRH (0.5 mu g kg(-1) body mass) each day while the testosterone-treated group received an i.m. injection of testosterone propionate (0.5 mg kg(-1) body mass) twice a day. The calves were studied until they were 200 days old. Hormone treatments were stopped one month after puberty was reached in the control group. Blood samples were collected every 30 min for 8 h every third day. Hormone concentrations were determined by radioimmunoassay. Western ligand blotting and immunoblotting, using monoclonal antibodies against IGFBP-2, and IGFBP-3, were used to characterize the IGF-binding proteins. In the control group, puberty occurred at about 120 days of age and was associated with an increase in concentrations of testosterone, IGF-I and IGFBP-3 and a decrease in concentration of IGFBP-2. In the GnRH-treated group, plasma testosterone remained low until 8 weeks after establishment of puberty in the control group (4 weeks after the end of treatment). In the testosterone-treated group, testosterone was high during the treatment period and then decreased to prepubertal values when treatment was stopped. Testosterone values increased again to reach postpubertal values 5 weeks after the end of hormone treatment. Nevertheless, independent of testosterone status, the profile of IGF-I and the IGFBPs in the GnRH- and testosterone-treated groups were parallel to that reported for the control group with the transition from prepubertal to adult values at about 120 days of age. In conclusion, concentrations of testosterone, IGF-I and IGFBP-3 increase together, but probably independently, during the onset of puberty in male calves. [less ▲]

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See detailDissociation of perceptual and motor inhibitory processes in young and elderly participants using the Simon task.
Germain, Sophie ULiege; Collette, Fabienne ULiege

in Journal of the International Neuropsychological Society (2008), 14(6), 1014-21

Deficits in inhibitory abilities are frequently observed in normal aging. However, few studies have explored the generality of these deficits in a single group of participants. Here, we used an adaptation ... [more ▼]

Deficits in inhibitory abilities are frequently observed in normal aging. However, few studies have explored the generality of these deficits in a single group of participants. Here, we used an adaptation of the Simon task to differentially assess perceptual and motor inhibition using the same stimuli and task design and to determine whether these processes use separate or shared cognitive resources. We were interested in determining whether (1) normal aging is associated with the use of separate (as previously evidenced in young participants) or similar cognitive resources to perform perceptual and motor inhibition tasks; (2) older participants present a specific impairment in one of these two processes. Analyses of reaction times indicated that motor and perceptual inhibitory processes share some cognitive resources and both are impaired in normal aging. These results can be interpreted by considering that a dedifferentiation process is responsible for the inhibitory deficits presented by older participants. [less ▲]

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See detailDissociation par compression graduée des voies motrices et arrestatrices contenues dans le faisceau de His
Fredericq, Léon ULiege

in Archives Internationales de Physiologie (1911), XI

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See detailDissociation par compression graduée des voies motriceset arrestatrices contenues dans le faisceau de His
Fredericq, Léon ULiege

in Bulletin de l'Académie Royale des Sciences, des Lettres et des Beaux-Arts de Belgique. Sciences (1911)

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See detailDissociation Pathways of Benzylpyridinium “Thermometer” Ions Depend on the Activation Regime: An IRMPD Spectroscopy Study
Morsa, Denis ULiege; Gabelica, Valérie ULiege; Rosu, Frédéric et al

in Journal of Physical Chemistry Letters (2014), 5

The dissociation of benzylpyridinium “thermometer” ions is widely used to calibrate the internal energy of ions produced in mass spectrometry. The fragmentation mechanism is usually believed to yield a ... [more ▼]

The dissociation of benzylpyridinium “thermometer” ions is widely used to calibrate the internal energy of ions produced in mass spectrometry. The fragmentation mechanism is usually believed to yield a benzylium cation, although recent studies suggest the possibility of a rearrangement leading to the tropylium isomer, which would compromise the accuracy of energy calibrations. In this study, we used IRMPD spectroscopy to probe the dissociation pathways of the p-(tert-butyl)- benzylpyridinium ion. Our results show that the formation of both benzylium and tropylium products is feasible depending on the activation regime and on the reaction time scale. Varying the trapping delays in the hexapole gives insight into a rearrangement mechanism occurring through consecutive reactions with an isomerization from benzylium to tropylium. Our work provides experimental validations for the established calibration procedure and highlights the adequacy of IRMPD spectroscopy to qualitatively resolve gas-phase rearrangement kinetics. [less ▲]

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See detailDissociations between categorization and similarity judgements as a result of learning feature distributions
Thibaut, Jean-Pierre; Dupont, Myriam; Anselme, Patrick ULiege

in Memory & Cognition (2002), 30(4), 647-656

A dissociation between categorization and similarity was found by Rips (1989). In one experiment, Rips found that a stimulus halfway between a pizza and a quarter was categorized as a pizza but was rated ... [more ▼]

A dissociation between categorization and similarity was found by Rips (1989). In one experiment, Rips found that a stimulus halfway between a pizza and a quarter was categorized as a pizza but was rated as more similar to a quarter. Smith and Sloman (1994) discussed these results in terms of the role of necessary and characteristic features. In two experiments, participants had to learn to categorize novel artificial shapes composed of a nonsalient necessary feature combined with a salient characteristic feature. Participants categorized stimuli on the basis of a necessary feature, whereas their similarity judgments relied on characteristic features. The role of deep (essential) features in dissociations is considered. Results are discussed in terms of the differences between requirements of categorization and similarity judgments. [less ▲]

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See detailDissociations between the processing of proper and common names
Brédart, Serge ULiege; Brennen, T.; Valentine, T.

in Cognitive Neuropsychology (1997), 14(2), 209-217

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See detailDissociations between verbal short-term memory and phonological processing in Williams syndrome.
Majerus, Steve ULiege; Barisnikov, K.; Poncelet, Martine ULiege et al

Conference (2003, August)

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See detailDissociative Autoionization as a Mechanism for the Proton Formation from Methane and Methane-d4 by low energy Electron Impact.
Locht, Robert ULiege; Olivier, J. L.; Momigny, J.

in Chemical Physics (1979), 43

The ion energy distribution and the electroionization efficiency curves of H+ and D+ from methane and methane-d4 have been examined. The existence of thermal ions is unambiguously evidenced and the two ... [more ▼]

The ion energy distribution and the electroionization efficiency curves of H+ and D+ from methane and methane-d4 have been examined. The existence of thermal ions is unambiguously evidenced and the two lowest appearance thresholds of H+ are measured at (21.3+/-0.3) eV and (22.17+/-0.1) eV. At both energies the protons have to be formed through dissociative autoionization. The present results closely parallel those of the dissociative excitation experiments on methane. The Jortner-Rice model for dissociation of polyatomic molecules is invoked to account for both the appearance of H+ and high-Rydberg H atoms from CH4. [less ▲]

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See detailThe Dissociative Electroionization of Ammonia and Ammonia-d3. I. The NH+ and NH2+ dissociation channels.
Locht, Robert ULiege; Servais, Christian ULiege; Ligot, M. et al

in Chemical Physics (1988), 123

The dissociative electroionization of NH3 (ND3) in the NH2+ (ND2+) and NH+(ND+) dissociation channels is investigated in the 15-50 eV electron energy range. The translational energy distributions of ND2 ... [more ▼]

The dissociative electroionization of NH3 (ND3) in the NH2+ (ND2+) and NH+(ND+) dissociation channels is investigated in the 15-50 eV electron energy range. The translational energy distributions of ND2+ (NH2+) exhibit several components whereas NH+ only shows a continuous broad distribution. For both ions a kinetic energy-versus-appearance energy diagram is obtained and discussed. The predissociation of the Jahn-Teller split NH3+(A2E) state produces both ions at their lowest threshold. At higher energies dissociative autoionization (in the 22 eV region), dissociative ionization through the NH3+(B2A1) state (in the 24-30 eV region) as well as by Coulomb repulsion of doubly ionized states (in the 35-50 eV region) produce NH2+(ND2+) and NH+ with large amounts of kinetic energy. Some arguments are brought forward to indicate that the former value of the NH2-H dissociation energy is overestimated. [less ▲]

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See detailThe Dissociative Electroionization of Ammonia and Ammonia-d3. II. The H+ and H2+ Dissociation Channels.
Locht, Robert ULiege; Servais, Christian ULiege; Ligot, M. et al

in Chemical Physics (1988), 125

The dissociative electroionization of NH3(ND3) in the H(D)+ and H(D)2+ dissociation channels is investigated in the 18-50 eV electron energy range. The H(D)+ translational energy distribution spectrum ... [more ▼]

The dissociative electroionization of NH3(ND3) in the H(D)+ and H(D)2+ dissociation channels is investigated in the 18-50 eV electron energy range. The H(D)+ translational energy distribution spectrum shows several components and that of H(D)2+ is continuous. The thermal energy component of the latter distribution is entirely ascribed to H2+/H2. For both ions the kinetic energy-versus-appearance energy diagram is obtained and discussed. The H+ ion at the lowest onset is probably formed at the expense of the NH3+(A2E) state. In the 22.5 eV electron energy range both H+ and H2+ are formed by dissociative autoionization. Evidence is also brought for H+ and H2+ formation at 22.5 eV and 26.5 eV through spontaneous decomposition of NH2+. Above 35 eV dissociation of doubly ionized states by Coulomb repulsion is mainly involved. [less ▲]

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See detailThe Dissociative Electroionization of Ammonia and Ammonia-d3. III. The N+ Dissociation Channel. General Conclusions about the Dissociation of NH3+.
Locht, Robert ULiege; Momigny, J.

in Chemical Physics (1988), 127

The dissociative ionization of NH3 is investigated in its N+ dissociation channel in the 20-50 eV electron energy range. Both the translational energy distribution and the appearance energies are measured ... [more ▼]

The dissociative ionization of NH3 is investigated in its N+ dissociation channel in the 20-50 eV electron energy range. Both the translational energy distribution and the appearance energies are measured. The kinetic energy-versus-appearance energy plot reveals seven N+ producing processes. Near the onset (22.5-24.0 eV) dissociative autoionization occurs whereas direct dissociative ionization produces N+ in the 24.5-30 eV range. Above 35 eV mainly N+/H+ ion pairs are formed at the expense of doubly ionized states. The dissociative electroionization work on NH3 being completed a review of the results is presented. [less ▲]

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See detailThe Dissociative Electroionization of C2H2, C2D2 and C2HD. Investigation of the [C2H(D)]+ and [H(D)]+ Dissociation Channels. The (D)H-C2H(D) binding energy.
Davister, M.; Locht, Robert ULiege

in Chemical Physics (1994), 189

The dissociative electroionization of C2H2 in the H+ and C2H+ dissociation channels has been extensively investigated in C2H2 and C2D2. The kinetic energy distributions and ionization efficiency curves of ... [more ▼]

The dissociative electroionization of C2H2 in the H+ and C2H+ dissociation channels has been extensively investigated in C2H2 and C2D2. The kinetic energy distributions and ionization efficiency curves of both species were examined in detail. The H(D)+ ion shows its lowest onset energy at 18.93+/-0.2 eV whereas the C2H+ is produced at 17.30+/-0.11 eV. For the H+-producing channel the kinetic energy (KE) versus the appearance energy (AE) diagram is obtained, extensively discussed and the bond dissociation energy D(H-C2H)= 5.33+/-0.23 eV is estimated. This value is compared and discussed with respect to the values found in the literature. Predissociation and dissociative autoionization are the dominant H+-producing mechanisms. At high electron energies doubly ionized states of C2H2 are involved. For C2H+, beside the threshold at 17.30+/0.11 eV a new onset at 18.27+/0.10 eV is observed. The ionization efficiency of the doubly ionized molecular ion is observed for the first time in C2HD isotopic species. [less ▲]

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See detailThe Dissociative Electroionization of Carbon Dioxide by low-energy Electron Impact. The C+, O+ and CO+ Dissociation channels.
Locht, Robert ULiege; Davister, M.

in International Journal of Mass Spectrometry and Ion Processes (1995), 144

This work reports the dissociative ionization of CO2 between 19-40 eV. The three dissociation channels producing C+, O+ and CO+ are examined in detail. Translational energy distributions as a function of ... [more ▼]

This work reports the dissociative ionization of CO2 between 19-40 eV. The three dissociation channels producing C+, O+ and CO+ are examined in detail. Translational energy distributions as a function of the impinging electron energy and the ionization efficiency for fixed kinetic energy carried away by the fragments are measured. The kinetic energy versus appearance energy diagram is obtained for the three fragment ions. When available, the present results are compared with previous measurements. The lowest appearance energy of O+ and CO+ corresponds to the predissociation of the CO2+ (C2Sigma +/g) state. At higher energies all the fragment ions are exclusively produced by the dissociative ionization of CO2 in the multiple electron transition (MET) states. Predissociation is most probably the dominant mechanism. Each MET state branches off to produce not only the three fragments but also the same fragment in two different states. This is observed for each dissociation channel, i.e. O+, CO+ and/or C+. In the latter channel no evidence is found for the dissociative ionization reaction CO2+->C++2O. [less ▲]

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See detailThe Dissociative Electroionization of NH3 and ND3. A detailed Study of its five Dissociation Channels.
Locht, Robert ULiege; Momigny, J.

in Longevialle, P. (Ed.) Advances in Mass Spectrometry. Volume 11A. (1988)

A general view of the results obtained for the dissociative ionization by electron impact on NH3 are presented. All five dissociation channels for the decomposition of the singly ionized NH3+ and the ... [more ▼]

A general view of the results obtained for the dissociative ionization by electron impact on NH3 are presented. All five dissociation channels for the decomposition of the singly ionized NH3+ and the doubly ionized (NH3)2+ are reported. [less ▲]

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See detailThe Dissociative Electroionization of NH3. The NH+ Dissociation Channel.
Locht, Robert ULiege; Servais, Christian ULiege; Ligot, M. et al

in Gilbody, H. B.; Newell, W. R.; Read, F. H. (Eds.) et al Electronic and Atomic Collisions: Abstracts of Contributed Papers. 15th International Conference on the Physics of Electronic and Atomic Collisions. Brighton, United Kingdom, 1987. (1987)

The dissociative electoionization efficiency of Nh3 in the NH+ channel is reported. The kinetic energy of this fragment ion is measured as a function of the impinging electron energy. Several dissociation ... [more ▼]

The dissociative electoionization efficiency of Nh3 in the NH+ channel is reported. The kinetic energy of this fragment ion is measured as a function of the impinging electron energy. Several dissociation limits are detected. [less ▲]

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See detailThe Dissociative Electroionization of Nitrous Oxide. The N+ and O+ Dissociation Channels.
Locht, Robert ULiege; Olivier, J. L.; Momigny, J.

in Schmid, E. R. (Ed.) Book of Abstracts of the 9th International Mass Spectrometry Conference (1982)

The first results on the dissociative elctroionization of nitrous oxide in the N+ and O+ dissociation channels are reported in the 15-32 eV electron energy range. Dissociation mechanisms at several ... [more ▼]

The first results on the dissociative elctroionization of nitrous oxide in the N+ and O+ dissociation channels are reported in the 15-32 eV electron energy range. Dissociation mechanisms at several critical energies are presented. [less ▲]

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See detailThe Dissociative Electroionization of Nitrous Oxide. The O+ Dissociation Channel.
Olivier, J. L.; Locht, Robert ULiege; Momigny, J.

in International Journal of Mass Spectrometry and Ion Physics (1983), 46

By electroionization mass spectrometry and ion kinetic energy analysis, the O+ fragment ion formation from N2O has been analyzed. Different appearance energies are measured and interpreted. Between the ... [more ▼]

By electroionization mass spectrometry and ion kinetic energy analysis, the O+ fragment ion formation from N2O has been analyzed. Different appearance energies are measured and interpreted. Between the onset at 15.27 eV and 22 eV only two dissociation limits are involved, i.e. O+(4S)+N2(X1Sigma+/g) at 15.29 eV and O+(2D)+N(X1Sigma+/g) at 18.61 eV. In both cases N2(X1Sigma+/g) is produced in its v=0 up to v=8 vibrational levels. Predissociation of ionic and Rydberg states of N2O are the dominant processes. [less ▲]

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See detailDissociative Electroionization Study in Acetylene. The Production of CH(D)+ in C2H2 and C2D2.
Davister, M.; Locht, Robert ULiege

in Andersen, T.; Fastrup, B.; Folkmann, F. (Eds.) et al Electronic and Atomic Collisions: Abstract of contributed Papers. (1993)

An extensive study of the dissociative electroionization of C2H2(D2) in the CH(D)+ producing channel is reported. The translational energy-versus-appearance energy diagram reveals 9 CH+-producing ... [more ▼]

An extensive study of the dissociative electroionization of C2H2(D2) in the CH(D)+ producing channel is reported. The translational energy-versus-appearance energy diagram reveals 9 CH+-producing processes involving C2H2+ and (C2H2)2+ ionic states and is discussed in detail. [less ▲]

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