bluuebunny/crossref_metadata_2025_split huggingface dataset:
Magnetic-Ion Interaction in Gd3Mn2Ge2GaO12 and Related Garnets
Authors: Gilleo M. A. , Geller S. 
Published: March 2008

The existence of appreciable (c)-(a) ferrimagnetic exchange interaction in the garnet structure has been established by the observation of ferrimagnetism in {Gd3}[Mn2](Ge2Ga)O12. [The dodecahedral, or 24(c), ions are enclosed by {}, the octahedral, or 16(a), ions by [] and the tetrahedral, or 24(d), ions by ().] The Néel temperature is about 8°K; the 1/χ vs T curve is linear for T&gt;35°K with an intercept of −8°K at 1/χ = 0 and a Curie constant of 5.6×10−3 μB deg per oersted per formula unit. The magnetic moment at 0°K probably corresponds to 3nB{Gd3+} −2nB[Mn2+] = 11 μB because the moments observed at temperatures between 4.2 and 1.5°K extrapolate to not less than 9.6 μB at 0°K. The moment decreases for the compositions, {MnGd2}[Mn2](Ge3)O12 and {CaGd2}[Mn2](Ge3)O12, in that order. In these three cases the 1/χ vs T curves are concave downward below 20°K, as would be expected in the case of ferrimagnetism.
No spontaneous magnetization is observed in {MnY2}[Mn2](Ge3)O12 and {CaY2}[Mn2](Ge3)O12 down to 1.3°K. For these compounds the 1/χ vs T curve is concave upward below 20°K as would be expected for a weak (a)-(a) antiferromagnetic interaction. Only a very weak (c)-(a) interaction is present in the first case as a consequence of one-third occupancy of dodecahedral sites by Mn2+ ions.
Theoretical Model for Cubic-to-Tetragonal Phase Transformations in Transition Metal Spinels
Authors: Wojtowicz Peter J. 
Published: March 2008

According to Dunitz and Orgel, the large tetragonal distortions which occur in a number of transition metal oxides having the spinel structure are presumed to arise as a consequence of a Jahn-Teller type distortion in the immediate environment of certain transition metal ions. All the observed large distortions can be correlated with the results of this crystal field treatment on the basis of the spatial ordering of the local distortions.
In this communication we investigate the detailed properties of the transformations from tetragonal to cubic phases which are observed at elevated temperatures. An approximate model has been constructed which explicitly takes into account the interactions between local Jahn-Teller distortions about neighboring B-site transition metal cations. By the use of the usual method of statistical mechanics it has proved possible to derive the thermodynamic behavior of this model, and hence to contribute to an understanding of the cooperative nature of these transformations. The principal result of importance is the demonstration that the transformations from tetragonal to cubic spinel phases are thermodynamically of the first order. That is, a latent heat, a volume discontinuity, lattice parameter discontinuities, and a lambda anomaly in the heat capacity are to be observed at the transformation temperature. The available evidence seems to support the conclusions drawn from the model.
Measurements of Rotational Magnetic Losses in Ferrites at Very Low Frequencies
Authors: Parker Hermon M. , Bullock B. W. , Dancy W. H. 
Published: March 2008

For some time this laboratory has been interested in the rotational magnetic losses in ferrites at low frequencies. Apparatus has been developed and successfully operated in which these losses are measured at frequencies of the order of 0.1 cps in fields up to about 5000 gauss and over a reasonably wide temperature range. It consists of a quartz fiber torsion pendulum (the fiber perpendicular to the field) operating in a vacuum and in a reasonably constant temperature enclosure. The principle involved is that of observing the decay of free oscillations of the system, and determining the torques due to the damped oscillatory system. By a process developed in our laboratory the samples are ground into spheres to accuracies of the order of 0.1% which can be improved it desired.
In the absence of magnetic anisotropy of the sample, the method can, in principle, distinguish between Coulomb or constant torque losses (customarily assumed for rotational hysteresis loss torque) and loss torques proportional to the angular velocity (viscous). However, for all samples so far measured the anisotropy has been sufficiently large to prevent the disentangling of the Coulomb and viscous losses. (Qualitative indications of the anisotropy are obtained from the measurements and it is interesting that the losses and anisotropy seem to be proportional.) The procedure has been to assume the losses are of the constant torque type and determine them by making the best engineering fit with the decay curves.
Technology and innovation in the psychosocial treatment of methamphetamine use, risk and dependence
Authors: KAY‐LAMBKIN FRANCES J. 
Published: March 2008

AbstractIssues. The dramatic increase in methamphetamine use has led to the urgent need for high‐quality, effective treatments and management strategies for methamphetamine use problems to be developed and disseminated. Although some evidence exists for the use of psychological, pharmacological and other approaches to treatment for problematic methamphetamine use, other evidence suggests that many methamphetamine users do not access these treatment options due to a range of individual and service‐level barriers. Approach. A review of available research literature was undertaken to identify treatment strategies for methamphetamine users, which overcome the problems associated with treatment access for this important target group and involve technological and other innovative approaches. Key Findings. Several approaches to addressing problematic methamphetamine use have been suggested, including assertive engagement strategies, flexibility in the provision of treatment and retention strategies and use of a multi‐focused intervention package, such as stepped care, perhaps including new technologies as alternatives or supplements to face‐to‐face‐delivered treatments. No research currently exists to examine the possible benefit of these strategies for people with methamphetamine use problems. Implications. The use of stepped‐care intervention packages has the potential to address many of the current challenges faced by both clinicians and clients in treating methamphetamine use problems. Conclusions. Although promising, these approaches require further attention and research effort, particularly among the specific group of methamphetamine users.
Trends in methamphetamine use in young injection drug users in San Francisco from 1998 to 2004: the UFO Study
Authors: INGLEZ‐DIAS ALINE , HAHN JUDITH A. , LUM PAULA J. , EVANS JENNIFER , DAVIDSON PETER , PAGE‐SHAFER KIMBERLY 
Published: March 2008

AbstractAims. To describe temporal trends in methamphetamine use among young injection drug users (IDU) in San Francisco. Design and Methods. Secondary analysis of cross‐sectional baseline data collected for a longitudinal study of young IDU from 1998 to 2004. Participants were 1445 young IDU (<30 years old) who reported injection in the previous month, English‐speaking, and recruited by street outreach methods. We examined trends for: lifetime (ever) and recent (30‐day) methamphetamine use, including injected and non‐injected, and by age group and sexual risk behaviour [men who have sex with men injecting drug users (MSM‐IDU), male IDU (non‐MSM) and female IDU]. Results. In 1998, 1999, 2000, 2001, 2003 and 2004 we interviewed 237, 276, 431, 310, 147 and 44 participants, respectively. Overall, median age was 22 years [interquartile range (IQR) 20–25], 30.3% were women and median duration of injecting was 4.4 years (IQR 2–7). Prevalence of methamphetamine use was high, with 50.1% reporting recent injection, but overall there were no temporal increases in reported ‘ever’ injected use. Recent methamphetamine injection (past 30 days) increased significantly, and peaked at 60% in 2003. MSM‐IDU had higher methamphetamine injection ever (92.3%) and recently (59.5%) compared to heterosexual male (non‐MSM) IDU (81.6% and 47.3%, respectively) and to female IDU (78.4% and 46.1%, respectively). Conclusions. Despite reports of ubiquitous increases in methamphetamine use, there were no significant increases in 6 years in ever injecting methamphetamine overall among young IDU. MSM‐IDU who reported the highest methamphetamine use overall reported some increases in recent injected use. The methamphetamine ‘epidemic’ was probably under way among young IDU earlier than other populations.
The rise of methamphetamine in Southeast and East Asia
Authors: McKETIN REBECCA , KOZEL NICHOLAS , DOUGLAS JEREMY , ALI ROBERT , VICKNASINGAM BALASINGAM , LUND JOHANNES , LI JIH‐HENG 
Published: March 2008

AbstractIntroduction and Aims. Southeast and East Asia has become a global hub for methamphetamine production and trafficking over the past decade. This paper describes the rise of methamphetamine supply and to what extent use of the drug is occurring in the region. Method and Design. The current review uses data collected through the Drug Abuse Information Network for Asia and the Pacific (DAINAP) and other available sources to analyse retrospectively methamphetamine trends within Southeast and East Asia. Results. Southeast and East Asia has experienced a methamphetamine epidemic in the past decade which began around 1997 and peaked in 2000–2001. While the situation has since stabilised in many countries, methamphetamine trafficking and use are still increasing in parts of the Mekong region and there is evidence of large‐scale manufacture in Cambodia, Indonesia, Malaysia and the Philippines. Methamphetamine is typically smoked or ingested, but injection of the drug is apparent. Conclusion. While the peak of the methamphetamine epidemic has passed in parts of Southeast and East Asia, attention is needed to minimise the potential consequences of spreading methamphetamine production, trafficking and use in the Mekong region and in the peninsular and archipelago of Southeast Asia.
Directional dispersal between mid‐ocean ridges: deep‐ocean circulation and gene flow in Ridgeia piscesae
Authors: YOUNG C. R. , FUJIO S. , VRIJENHOEK R. C. 
Published: March 2008

AbstractThis study examined relationships between bathymetrically induced deep‐ocean currents and the dispersal of the hydrothermal vent tubeworm Ridgeia piscesae along the northeast Pacific ridge system. A robust diagnostic model of deep‐ocean circulation in this region predicted strong southeasterly currents following contours of the Blanco Transform Fault, a 450‐km lateral offset that separates the Gorda and Juan de Fuca ridge systems. Such currents should facilitate the southward dispersal of R. piscesae larvae. Immigration rates for populations north and south of the Blanco Transform Fault were estimated from molecular population genetic data. Mitochondrial DNA evidence revealed population subdivision across the Blanco Transform Fault, and a strong directional bias in gene flow that was consistent with predictions of the circulation model. The distribution of mitochondrial diversity between the northern and southern populations of R. piscesae suggests that the Gorda Ridge tubeworms have maintained larger effective population sizes than the northern populations, a pattern that also exists in co‐occurring limpets. Together, these data suggest that the northern vent fields may experience a higher frequency of habitat turnover and consequently more rapid losses of genetic diversity.
Characterization of resistance gene analogs with a nucleotide binding site isolated from a triploid white poplar
Authors: Zhang Q. , Zhang Z.‐Y. , Lin S.‐Z. , Zheng H.‐Q. , Lin Y.‐Z. , An X.‐M. , Li Y. , Li H.‐X. 
Published: March 2008

AbstractThe majority of cloned plant disease resistance genes (R genes) encode a nucleotide binding site (NBS) and a leucine‐rich repeat (LRR) domain. In this study, to better understand the R genes in white poplar, 59 resistance gene analogues (RGAs) were identified from a triploid white poplar [(Populus tomentosa × Populus bolleana) × P. tomentosa], based on conserved NBS regions. The 59 RGAs were phylogenetically classified into 10 subfamilies, and 54 RGAs with open‐reading frames (ORFs) were further grouped into two classes, toll and interleukin‐1 receptor (TIR) and non‐TIR. BLAST searches with reference to the genomic sequence of Populus trichocarpa found 96 highly homologous regions distributed in 37 loci, suggesting the abundance and divergence of NBS‐encoding genes in the triploid poplar genome. Within subfamilies 1–3, the average non‐synonymous/synonymous substitution (ω) rates were < 1, indicating purifying selection on these RGAs, but some sites were clearly under diversifying selection with ω > 1. Many intergenic exchanges were also detected among these RGAs, indicating a probable role in homogenising NBS domains. Quantitative real‐time PCR analysis revealed dramatic variations in the transcript level of 18 RGAs in the mature leaves, bark and roots of the triploid poplar, and identified two RGAs that had significantly higher level of transcripts in bark, four RGAs in mature leaves, and 14 in the above‐ground portion of poplars, suggesting their probable roles in resistance against diseases attacking the organs. Our results shed light on genetic resources of poplar resistance and will be useful for further resistance gene isolation and exploitation.
Antioxidative enzymes and the Russian wheat aphid (Diuraphis noxia) resistance response in wheat (Triticum aestivum)
Authors: Moloi M. J. , Van Der Westhuizen A. J. 
Published: March 2008

AbstractA crucial function of antioxidative enzymes is to remove excess reactive oxygen species (ROS), which can be toxic to plant cells. The effect of Russian wheat aphid (RWA), Diuraphis noxia (Mordvilko), infestation on the activities of antioxidative enzymes was investigated in the resistant (cv. Tugela DN) and the near‐isogenic susceptible (cv. Tugela) wheat (Triticum aestivum L.). RWA infestation significantly induced the activity of superoxide dismutase, glutathione reductase and ascorbate peroxidase to higher levels in the resistant than in susceptible plants. These findings suggest the involvement of antioxidative enzymes in the RWA–wheat resistance response, which was accompanied by an early oxidative burst. The results are consistent with the role of ROS in the resistance response and the control of their levels to minimise toxic effects.
Obstacle stepping involves spinal anticipatory activity associated with quadrupedal limb coordination
Authors: Michel J. , Van Hedel H. J. A. , Dietz V. 
Published: March 2008

AbstractObstacle avoidance steps are associated with a facilitation of spinal reflexes in leg muscles. Here we have examined the involvement of both leg and arm muscles. Subjects walking with reduced vision on a treadmill were acoustically informed about an approaching obstacle and received feedback about task performance. Reflex responses evoked by tibial nerve stimulation were observed in all arm and leg muscles examined in this study. They were enhanced before the execution of obstacle avoidance compared with normal steps and showed an exponential adaptation in contralateral arm flexor muscles corresponding to the improvement of task performance. This enhancement was absent when the body was partially supported during the task. During the execution of obstacle steps, electromyographic activity in the arm muscles mimicked the preceding reflex behaviour with respect to enhancement and adaptation. Our results demonstrate an anticipatory quadrupedal limb coordination with an involvement of proximal arm muscles in the acquisition and performance of this precision locomotor task. This is presumably achieved by an up‐regulated activity of coupled cervico‐thoracal interneuronal circuits.
Neglect‐like visual exploration behaviour after theta burst transcranial magnetic stimulation of the right posterior parietal cortex
Authors: Nyffeler Thomas , Cazzoli Dario , Wurtz Pascal , Lüthi Mathias , Von Wartburg Roman , Chaves Silvia , Déruaz Anouk , Hess Christian W. , Müri René M. 
Published: March 2008

AbstractThe right posterior parietal cortex (PPC) is critically involved in visual exploration behaviour, and damage to this area may lead to neglect of the left hemispace. We investigated whether neglect‐like visual exploration behaviour could be induced in healthy subjects using theta burst repetitive transcranial magnetic stimulation (rTMS). To this end, one continuous train of theta burst rTMS was applied over the right PPC in 12 healthy subjects prior to a visual exploration task where colour photographs of real‐life scenes were presented on a computer screen. In a control experiment, stimulation was also applied over the vertex. Eye movements were measured, and the distribution of visual fixations in the left and right halves of the screen was analysed. In comparison to the performance of 28 control subjects without stimulation, theta burst rTMS over the right PPC, but not the vertex, significantly decreased cumulative fixation duration in the left screen‐half and significantly increased cumulative fixation duration in the right screen‐half for a time period of 30 min. These results suggest that theta burst rTMS is a reliable method of inducing transient neglect‐like visual exploration behaviour.
Feed‐forward excitation of striatal neuron activity by frontal cortical activation of nitric oxide signaling in vivo
Authors: Ondracek Janie M. , Dec Alexander , Hoque Kristina E. , Lim Sean Austin O. , Rasouli Golta , Indorkar Raksha P. , Linardakis John , Klika Brian , Mukherji Sawrav Josh , Burnazi Migena , Threlfell Sarah , Sammut Stephen , West Anthony R. 
Published: March 2008

AbstractThe gaseous neurotransmitter nitric oxide plays an important role in the modulation of corticostriatal synaptic transmission. This study examined the impact of frontal cortex stimulation on striatal nitric oxide efflux and neuron activity in urethane‐anesthetized rats using amperometric microsensor and single‐unit extracellular recordings, respectively. Systemic administration of the neuronal nitric oxide synthase inhibitor 7‐nitroindazole decreased spontaneous spike activity without affecting activity evoked by single‐pulse stimulation of the ipsilateral cortex. Train (30 Hz) stimulation of the contralateral frontal cortex transiently increased nitric oxide efflux in a robust and reproducible manner. Evoked nitric oxide efflux was attenuated by systemic administration of 7‐nitroindazole and the non‐selective nitric oxide synthase inhibitor NG‐nitro‐l‐arginine methyl ester. Train stimulation of the contralateral cortex, in a manner identical to that used to evoke nitric oxide efflux, had variable effects on spike activity assessed during the train stimulation trial, but induced a short‐term depression of cortically evoked activity in the first post‐train stimulation trial. Interestingly, 7‐nitroindazole potently decreased cortically evoked activity recorded during the train stimulation trial. Moreover, the short‐term depression of spike activity induced by train stimulation was enhanced following pretreatment with 7‐nitroindazole and attenuated after systemic administration of the dopamine D2 receptor antagonist eticlopride. These results demonstrate that robust activation of frontal cortical afferents in the intact animal activates a powerful nitric oxide‐mediated feed‐forward excitation which partially offsets concurrent D2 receptor‐mediated short‐term inhibitory influences on striatal neuron activity. Thus, nitric oxide signaling is likely to play an important role in the integration of corticostriatal sensorimotor information in striatal networks.
Do patients with psychogenic nonepileptic seizures produce trustworthy findings on neuropsychological tests?
Authors: Dodrill Carl B. 
Published: March 2008

Summary Drane et al. (2006) has recently raised the possibility that patients with psychogenic nonepileptic seizures (PNES) may make poor effort in taking neuropsychological tests in comparison with patients with epilepsy (ES). Therefore, findings previously reported with PNES patients may be in error, especially with regard to tests of mental abilities. Using the same measure of effort used by Drane et al. (2006) but with more broadly selected patients, this paper attempts to replicate their findings with new samples of ES (n = 65) and PNES (n = 32) cases. However, their findings could not be replicated, and no differences in test taking effort could be demonstrated across the groups. The highly selected samples of Drane et al. (2006) appear to be responsible for their results, and neuropsychological findings with PNES patients appear to be as trustworthy as those with ES patients.
Aborted and refractory status epilepticus in children: A comparative analysis
Authors: Lambrechtsen Florise A. C. P. , Buchhalter Jeffrey R. 
Published: March 2008

Summary
Purpose: The aims of this retrospective study were: (1) to compare the demographics, clinical characteristics, etiology, and EEG findings of status epilepticus aborted with medication (ASE) and refractory status epilepticus (RSE), (2) to describe the treatment response of status epilepticus (SE), and (3) to determine predictors of long‐term outcome in children with SE.
Methods: Medical records and EEG lab logs with ICD‐9 diagnostic codes related to SE were reviewed. Patients younger than 18 years of age, hospitalized in 1994–2004 at the Mayo Clinic, Rochester, were included.
Results: One hundred fifty‐four children had SE; 94 (61%) had ASE, and 60 (39.0%) had RSE. Family history of seizures, higher seizure frequency score, higher number of maintenance antiepileptic drugs (AEDs), nonconvulsive SE, and focal or electrographic seizures on initial EEG were associated with RSE by univariate analysis. In‐hospital mortality was significantly higher in RSE (13.3%) than in ASE (2.1%). In the long term, survivors with RSE developed more new neurological deficits (p < 0.001) and more epilepsy (p < 0.004) than children with ASE. Children treated in a more aggressive fashion appeared to have better treatment responses (p < 0.001) and outcomes (p = 0.03). Predictors of poor outcome were long seizure duration (p < 0.001), acute symptomatic etiology (p = 0.04), nonconvulsive SE (NCSE) (p = 0.01), and age at admission <5 years (p = 0.05).
Discussion: Several patient and clinical characteristics are associated with development of RSE and poor outcome. Prospective, randomized trials that assess different treatment protocols in children with SE are needed to determine the optimal sequence and timing of medications.