fMRI Investigation of Cortical and Subcortical Networks in the Learning of Abstract and Effector-Specific Representations of Motor Sequences

A visuomotor sequence can be learned as a series of visuo-spatial cues or as a sequence of effector movements. Earlier imaging studies have revealed that a network of brain areas is activated in the course of motor sequence learning. However these studies do not address the question of the type of representation being established at various stages of visuomotor sequence learning. In an earlier behavioral study, we demonstrated that acquisition of visuo-spatial sequence representation enables rapid learning in the early stage and progressive establishment of somato-motor representation helps speedier execution by the late stage. We conducted functional magnetic resonance imaging (fMRI) experiments wherein subjects learned and practiced the same sequence alternately in normal and rotated settings. In one rotated setting (visual), subjects learned a new motor sequence in response to an identical sequence of visual cues as in normal. In another rotated setting (motor), the display sequence was altered as compared to normal, but the same sequence of effector movements were used to perform the sequence. Comparison of different rotated settings revealed analogous transitions both in the cortical and subcortical sites during visuomotor sequence learning  a transition of activity from parietal to parietal-premotor and then to premotor cortex and a concomitant shift was observed from anterior putamen to a combined activity in both anterior and posterior putamen and finally to posterior putamen. These results suggest a putative role for engagement of different cortical and subcortical networks at various stages of learning in supporting distinct sequence representations

Clinical evaluation of an anatomy-based patient specific quality assurance system

The Delta4DVH Anatomy 3D quality assurance (QA) system (ScandiDos), which converts the measured detector dose into the dose distribution in the patient geometry was evaluated. It allows a direct comparison of the calculated 3D dose with the measured back-projected dose. In total, 16 static and 16 volumetric-modulated arc therapy (VMAT) fields were planned using four different energies. Isocenter dose was measured with a pinpoint chamber in homogeneous phantoms to investigate the dose prediction by the Delta4DVH Anatomy algorithm for static fields. Dose distributions of VMAT fields were measured using GAFCHROMIC film. Gravitational gantry errors up to 10° were introduced into all VMAT plans to study the potential of detecting errors. Additionally, 20 clinical treatment plans were verified. For static fields, the Delta4DVH Anatomy predicted the isocenter dose accurately, with a deviation to the measured phantom dose of 1.1% ± 0.6%. For VMAT fields the predicted Delta4DVH Anatomy dose in the isocenter plane corresponded to the measured dose in the phantom, with an average gamma agreement index (GAI) (3 mm/3%) of 96.9± 0.4%. The Delta4DVH Anatomy detected the induced systematic gantry error of 10° with a relative GAI (3 mm/3%) change of 5.8% ± 1.6%. The conventional Delta4PT QA system detected a GAI change of 4.2%± 2.0%. The conventional Delta4PT GAI (3 mm/3%) was 99.8% ± 0.4% for the clinical treatment plans. The mean body and PTV-GAI (3 mm/5%) for the Delta4DVH Anatomy were 96.4% ± 2.0% and 97.7%± 1.8%; however, this dropped to 90.8%± 3.4% and 87.1% ± 4.1% for passing criteria of 3 mm/3%. The anatomy-based patient specific quality assurance system predicts the dose distribution correctly for a homogeneous case. The limiting factor for the error detection is the large variability in the error-free plans. The dose calculation algorithm is inferior to that used in the TPS (Eclipse)

The effect of lutein- and zeaxanthin-rich foods v. supplements on macular pigment level and serological markers of endothelial activation inflammation and oxidation pilot studies in healthy volunteers: pilot studies in healthy volunteers

The aim of the present study was to compare the effect of lutein- and zeaxanthin-rich foods and supplements on macular pigment level (MPL) and serological markers of endothelial activation, inflammation and oxidation in healthy volunteers. We conducted two 8-week intervention studies. Study 1 (n 52) subjects were randomised to receive either carrot juice (a carotene-rich food) or spinach powder (a lutein- and zeaxanthin-rich food) for 8 weeks. Study 2 subjects (n 75) received supplements containing lutein and zeaxanthin, β-carotene, or placebo for 8 weeks in a randomised, double-blind, placebo-controlled trial. MPL, serum concentrations of lipid-soluble antioxidants, inter-cellular adhesion molecule 1, vascular cell adhesion molecule 1, C-reactive protein and F2-isoprostane levels were assessed at baseline and post-intervention in both studies. In these intervention studies, no effects on MPL or markers of endothelial activation, inflammation or oxidation were observed. However, the change in serum lutein and zeaxanthin was associated or tended to be associated with the change in MPL in those receiving lutein- and zeaxanthin-rich foods (lutein r 0·40, P = 0·05; zeaxanthin r 0·30, P = 0·14) or the lutein and zeaxanthin supplement (lutein r 0·43, P = 0·03; zeaxanthin r 0·22, P = 0·28). In both studies, the change in MPL was associated with baseline MPL (food study r − 0·54, P &lt; 0·001; supplement study r − 0·40, P &lt; 0·001). We conclude that this 8-week supplementation with lutein and zeaxanthin, whether as foods or as supplements, had no significant effect on MPL or serological markers of endothelial activation, inflammation and oxidation in healthy volunteers, but may improve MPL in the highest serum responders and in those with initially low MPL.</jats:p

Photonic crystals of coated metallic spheres

It is shown that simple face-centered-cubic (fcc) structures of both metallic and coated metallic spheres are ideal candidates to achieve a tunable complete photonic bandgap (CPBG) for optical wavelengths using currently available experimental techniques. For coated microspheres with the coating width to plasma wavelength ratio $l_c/\lambda_p \leq 10$ and the coating and host refractive indices $n_c$ and $n_h$, respectively, between 1 and 1.47, one can always find a sphere radius $r_s$ such that the relative gap width $g_w$ (gap width to the midgap frequency ratio) is larger than 5% and, in some cases, $g_w$ can exceed 9%. Using different coatings and supporting liquids, the width and midgap frequency of a CPBG can be tuned considerably.Comment: 14 pages, plain latex, 3 ps figures, to appear in Europhys. Lett. For more info on this subject see http://www.amolf.nl/research/photonic_materials_theory/moroz/moroz.htm

Bostonia: The Boston University Alumni Magazine. Volume 11

Founded in 1900, Bostonia magazine is Boston University's main alumni publication, which covers alumni and student life, as well as university activities, events, and programs

The International Alcohol Control Study: Methodology and implementation.

INTRODUCTION AND AIMS: The International Alcohol Control (IAC) Study is a multi-country collaborative project to assess patterns of alcohol consumption and the impact of alcohol control policy. The aim of this paper is to report the methods and implementation of the IAC. DESIGN AND METHODS: The IAC has been implemented among drinkers 16-65 years in high- and middle-income countries: Australia, England, Scotland, New Zealand, St Kitts and Nevis, Thailand, South Africa, Peru, Mongolia and Vietnam (the latter four samples were sub-national). Two research instruments were used: the IAC survey of drinkers and the Alcohol Environmental Protocol (a protocol for policy analysis). The survey was administered via computer-assisted interview and the Alcohol Environmental Protocol data were collected via document review, administrative or commercial data and key informant interviews. RESULTS: The IAC instruments were readily adapted for cross-country use. The IAC methodology has provided cross-country survey data on key measures of alcohol consumption (quantity, frequency and volume), aspects of policy relevant behaviour and policy implementation: availability, price, purchasing, marketing and drink driving. The median response rate for all countries was 60% (range 16% to 99%). Where data on alcohol available for consumption were available the validity of survey consumption measures were assessed by calculating survey coverage found to be 86% or above. Differential response bias was handled, to the extent it could be, using post-stratification weights. DISCUSSION AND CONCLUSIONS: The IAC study will allow for cross-country analysis of drinking patterns, the relationship between alcohol use and policy relevant behaviour in different countries

Heat Treated NiP–SiC Composite Coatings: Elaboration and Tribocorrosion Behaviour in NaCl Solution

Tribocorrosion behaviour of heat-treated NiP and NiP–SiC composite coatings was investigated in a 0.6 M NaCl solution. The tribocorrosion tests were performed in a linear sliding tribometer with an electrochemical cell interface. It was analyzed the influence of SiC particles dispersion in the NiP matrix on current density developed, on coefficient of friction and on wear volume loss. The results showed that NiP–SiC composite coatings had a lower wear volume loss compared to NiP coatings. However, the incorporation of SiC particles into the metallic matrix affects the current density developed by the system during the tribocorrosion test. It was verified that not only the volume of co-deposited particles (SiC vol.%) but also the number of SiC particles per coating area unit (and consequently the SiC particles size) have made influence on the tribocorrosion behaviour of NiP–SiC composite coatings

Estimation of speciated and total mercury dry deposition at monitoring locations in eastern and central North America

Dry deposition of speciated mercury, i.e., gaseous oxidized mercury (GOM), particulate-bound mercury (PBM), and gaseous elemental mercury (GEM), was estimated for the year 2008–2009 at 19 monitoring locations in eastern and central North America. Dry deposition estimates were obtained by combining monitored two- to four-hourly speciated ambient concentrations with modeled hourly dry deposition velocities (&lt;i&gt;V&lt;/i&gt;&lt;sub&gt;d&lt;/sub&gt;) calculated using forecasted meteorology. Annual dry deposition of GOM+PBM was estimated to be in the range of 0.4 to 8.1 μg m&lt;sup&gt;−2&lt;/sup&gt; at these locations with GOM deposition being mostly five to ten times higher than PBM deposition, due to their different modeled &lt;i&gt;V&lt;/i&gt;&lt;sub&gt;d&lt;/sub&gt; values. Net annual GEM dry deposition was estimated to be in the range of 5 to 26 μg m&lt;sup&gt;−2&lt;/sup&gt; at 18 sites and 33 μg m&lt;sup&gt;−2&lt;/sup&gt; at one site. The estimated dry deposition agrees very well with limited surrogate-surface dry deposition measurements of GOM and PBM, and also agrees with litterfall mercury measurements conducted at multiple locations in eastern and central North America. This study suggests that GEM contributes much more than GOM+PBM to the total dry deposition at the majority of the sites considered here; the only exception is at locations close to significant point sources where GEM and GOM+PBM contribute equally to the total dry deposition. The relative magnitude of the speciated dry deposition and their good comparisons with litterfall deposition suggest that mercury in litterfall originates primarily from GEM, which is consistent with the limited number of previous field studies. The study also supports previous analyses suggesting that total dry deposition of mercury is equal to, if not more important than, wet deposition of mercury on a regional scale in eastern North America