STM topography and manipulation of single Au atoms on Si(100)

The low-temperature (12 K) adsorption of single Au atoms on Si(100) is studied by scanning tunneling microscopy (STM). Comparison between experimental and calculated STM topographies as well as density-functional-theory calculations of the adsorption energies enable us to identify two adsorption configurations of Au atoms between Si-dimer rows (BDRs) and on top of Si-dimer rows (TDRs). In both adsorption configurations, the Au atoms are covalently bound to two Si atoms through a partial electron transfer from Si to Au. STM manipulation confirms that the TDR adsorption configuration is metastable, whereas the BDR one is the most stable configuration.Peer reviewe

The temporal dynamics of visual processing in multiple sclerosis

Although the integrity of the visual system is often affected in multiple sclerosis (MS), the potential relationship between the temporal dynamics of visual processing and performance on neuropsychological tests assessing processing speed (PS) remains relatively unexplored. Here, we test if a PS deficit is related to abnormalities within the visual system, rather than impaired higher-level cognitive function. Two groups of participants with MS (1 group with PS deficits and another without) and a healthy control group, matched for age and education, were included. To explore the temporal dynamics of visual processing, we used 2 psychophysical paradigms: attention enhancement/prioritization and rapid serial visual presentation. Visual PS deficits were associated with a decreased capability to detect visual stimuli and a higher limitation in visual temporal-processing capacity. These results suggest that a latent sensorial temporal limitation of the visual system is significantly associated to PS deficits in MS.This work was supported by the Foundation for Science and Technology of Portugal with a doctoral fellowship grant (No. SFRH/BD/455591/2008) to SLC. JA is supported by funding from the Foundation for Science and Technology of Portugal Project Grants PTDC/PSI-PCO/114822/2009 and PTDC/MHC-PCN/3575/2012.info:eu-repo/semantics/publishedVersio

Prognostic value of18 f-choline pet/ct in patients with metastatic castration-resistant prostate cancer treated with radium-223

We aimed to investigate the role of positron emission computed tomography (PET/CT) with F-18-choline for predicting the outcome of metastatic castration-resistant prostate cancer (mCRPC) submitted to treatment with Radium-223 (Ra-223-therapy). Clinical records of 20 mCRPC patients submitted to PET/CT with F-18-choline before Ra-223-therapy were retrospectively evaluated. The following PET-derived parameters were calculated: number of lesions, maximum and mean standardized uptake values (SUVmax, SUVmean), lean body mass corrected SUV peak (SULpeak), metabolic tumor volume (MATV), and total lesion activity (TLA). After Ra-223-therapy, all patients underwent regular follow-up until death. The predictive power of clinical and PET-derived parameters on overall survival (OS) was assessed by Kaplan-Meier analysis and the Cox proportional hazard method. All the patients showed F-18-choline-avid lesions at baseline PET/CT. Among the enrolled subjects, eleven (55%) completed all the six scheduled cycles of Ra-223-therapy; seven (35%) were responders according to imaging and biochemical parameters. Mean OS was 12.7 +/- 1.4 months: by Kaplan-Meier analysis, number of lesions, PSA level and TLA were significantly correlated with OS. In multivariate Cox analysis, TLA remained the only significant predictor of survival (p = 0.003; hazard ratio = 7.6, 95% confidence interval = 1.9-29.5 months). F-18-choline PET may be useful for patients' stratification before Ra-223-therapy. In particular, high metabolically active tumor burden (i.e., TLA) was predictive of poor outcome

Are cognitive interventions for multiple sclerosis effective and feasible?

Purpose: Fifty percent of patients with Multiple Sclerosis (MS) are estimated to have cognitive impairments leading to considerable decline in productivity and quality of life. Cognitive intervention has been considered to complement pharmacological treatments. However, a lack of agreement concerning the efficacy of cognitive interventions in MS still exists. A systematic review and meta-analysis was conducted to assess the effects of cognitive interventions in MS. Methods: To overcome limitations of previous meta-analyses, several databases were searched only for Randomized Clinical Trials (RCTs) with low risk of bias. Results: Five studies (total of 139 participants) met our eligibility criteria. Although good completion and adherence rates were evident, we found no evidence of intervention effects on cognition or mood in post-intervention or follow-up assessments. Conclusions: This is the first meta-analysis assessing the effects of cognitive intervention in MS including only RCTs with comparable conditions. Research regarding efficacy, cost-effectiveness and feasibility is still in its infancy. Caution is advised when interpreting these results due to the small number of RCTs meeting the inclusion criteria. Considering the costs of disease, good completion and adherence rates of this approach, further research is warranted. Recommendations concerning improved research practices in the field are presented as well.R.M. and J.A. are supported by doctoral Grants from Fundac¸ao para a Ci ˜ encia e Tecnologia (FCT) ˆ (SFRH/BD/65213/2009, SFRH/BD/64457/2009 and co-funded by FSE/POPH). A.S. is funded for the project PIC/IC/83290/2007, supported by FEDER (POFC–COMPETE) and FCT to develop and assess the effectiveness of a cognitive stimulation tool for Portuguese clinicians