81 research outputs found
Mesure de rĂ©sultats des travaux communautaires chez les jeunes contrevenants : lâI.Ă.R.T.C.
The community work program is designed for young offenders between the ages of 12 and 17. Participants are allowed to make restitution for their delinquent acts by working a certain number of hours in a neighborhood organization. Aside from this work aspect, the program also aims at arriving at various short-term results that serve as indications of the program's impact on participants. The lack of instruments able to systematically collect data for this purpose led to the creation of the Community Work Evaluation Tool (CWET). Grounded in the objectives of the community work program, the CWET measures the process by which its 13 items were arrived at, its validation and its psychometric properties. The CWET is argued to be a valid tool for evaluating the effects of such a program. These effects fall along four areas: (1) the personal evolution of each participant; (2) the participant's commitment to the completion of the program; (3) relationships between participants; and (4) the participant's attitude and openness toward the community
Switchgrass storage effects on the recovery of carbohydrates after liquid hot water pretreatment and enzymatic hydrolysis
Perennial grasses that would be used for bioenergy and bioproducts production will need to be stored for various periods of time to ensure a continual feedstock supply to a bioprocessing facility. The effects of storage practices on grass composition and the response of grasses to subsequent bioprocesses such as pretreatment and enzymatic hydrolysis needs to be understood to develop the most efficient storage protocols. This study examined the effect of outdoor storage of round switchgrass bales on composition before and after liquid hot water pretreatment (LHW) and enzymatic hydrolysis. This study also examined the effect of washing LHW pretreated biomass prior to enzymatic hydrolysis. It was determined that switchgrass composition after baling was stable. As expected, glucan and lignin contents increased after LHW due to decreases in xylan and galactan. Washing biomass prior to enzymatic hydrolysis reduced saccharification, especially in samples from the interior of the bale, by at least 5%
Kinetics determination of soybean oil transesterification in the design of a continuous biodiesel production process
One-step batch transesterification consisting of three stepwise reversible reactions of pure soybean oil with methanol was conducted at two different mixing speeds (600 and 300 rpm) to produce soybean oil fatty acid methyl esters (biodiesel). In both batch reactions, sodium methoxide (1.09 wt% based on soybean oil) was used as the catalyst, the reaction temperature was 60oC, and the methanol-to-oil molar ratio was 6:1. The objectives were to determine and/or investigate: 1) the mechanism and order of the reaction, 2) the reaction rate constants, 3) the effect of changes in mixing intensity on the reaction rate, 4) the comparison of the reaction mechanism and kinetic rate constants calculated with established literature references (for validation), and 5) how to interpret and utilize the kinetics analysis in the design of a continuous pilot-scale biodiesel production process. The kinetics analysis from the experiment showed that a second-order kinetic mechanism provided a good fit for the reaction. Kinetic rate constants at both mixing speeds were calculated and ranged from -3.10 x 10-3 - 0.028 (wt% min)-1 for the triglyceride, monoglyceride, and diglyceride forward reactions. The rate constants were slightly higher at the 600 rpm mixing speed. Higher mixing intensity also resulted in an increased purity of methyl esters (95.2 wt %). At both mixing speeds, monoglycerides showed the smallest percent elimination of all reaction intermediates at approximately 30%. The rate constants calculated for monoglycerides were the lowest as well. The monoglyceride rate constant of 0.0149 (wt% min)-1 was used in the design of a continuous process in a 100 gallon vessel, which is a scale of operation that could be easily adopted by a cooperative of oil seed producers or geographically isolated plant-oil producing villages. This Honors thesis was a component of a Biological and Agricultural Engineering team Senior Design project which consisted of designing a continuous biodiesel process from production to purification
The Effect of Water Extracted Silibinin on Reactive Oxygen Species (ROS) Production of Macrophages
The world is actively looking for technology to produce sustainable liquid fuels to replace our reliance on petroleum-based fuels. Biomass can be converted either through the thermochemical or saccharification platforms into fuels such as ethanol or butanol. In addition to converting the biomass into liquid fuels, valuable phytochemicals can be extracted prior, during, or after the conversion. Extracting useful phytochemicals, as a part of the overall conversion of biomass to fuels, is included in the concept of the biobased biorefinery. However, the key to effectively and economically extract phytochemicals from biomass is the ability to couple the extraction to the energy conversion steps; that is, extraction with either dilute acid or water. Phytochemical extraction with organic solvents cannot be easily coupled with an energy conversion process because the solvents must be removed before proceeding to energy conversion, thereby complicating and increasing the cost of the process. By extracting the phytochemicals with water or dilute acid, a simple unit operation can be added to the existing biomass conversion technology, ultimately adding value to the biomass
Brain white matter damage and its association with neuronal synchrony during sleep
The restorative function of sleep partly relies on its ability to deeply synchronize cerebral networks to create large slow oscillations observable with EEG. However, whether a brain can properly synchronize and produce a restorative sleep when it undergoes massive and widespread white matter damage is unknown. Here, we answer this question by testing 23 patients with various levels of white matter damage secondary to moderate to severe traumatic brain injuries (ages 18â56; 17 males, six females, 11â39 months post-injury) and compared them to 27 healthy subjects of similar age and sex. We used MRI and diffusion tensor imaging metrics (e.g. fractional anisotropy as well as mean, axial and radial diffusivities) to characterize voxel-wise white matter damage. We measured the following slow wave characteristics for all slow waves detected in N2 and N3 sleep stages: peak-to-peak amplitude, negative-to-positive slope, negative and positive phase durations, oscillation frequency, and slow wave density. Correlation analyses were performed in traumatic brain injury and control participants separately, with age as a covariate. Contrary to our hypotheses, we found that greater white matter damage mainly over the frontal and temporal brain regions was strongly correlated with a pattern of higher neuronal synchrony characterized by slow waves of larger amplitudes and steeper negative-to-positive slopes during non-rapid eye movement sleep. The same pattern of associations with white matter damage was also observed with markers of high homeostatic sleep pressure. More specifically, higher white matter damage was associated with higher slow-wave activity power, as well as with more severe complaints of cognitive fatigue. These associations between white matter damage and sleep were found only in our traumatic brain injured participants, with no such correlation in controls. Our results suggest that, contrary to previous observations in healthy controls, white matter damage does not prevent the expected high cerebral synchrony during sleep. Moreover, our observations challenge the current line of hypotheses that white matter microstructure deterioration reduces cerebral synchrony during sleep. Our results showed that the relationship between white matter and the brainâs ability to synchronize during sleep is neither linear nor simple
Sleep spindles are resilient to extensive white matter deterioration
Sleep spindles are an essential part of non-rapid eye movement sleep, notably involved in sleep consolidation, cognition, learning
and memory. These oscillatory waves depend on an interaction loop between the thalamus and the cortex, which relies on a structural backbone of thalamo-cortical white matter tracts. It is still largely unknown if the brain can properly produce sleep spindles
when it underwent extensive white matter deterioration in these tracts, and we hypothesized that it would affect sleep spindle generation and morphology. We tested this hypothesis with chronic moderate to severe traumatic brain injury (n Œ 23;
30.5 6 11.1 years old; 17 m/6f), a unique human model of extensive white matter deterioration, and a healthy control group
(n Œ 27; 30.3 6 13.4 years old; 21m/6f). Sleep spindles were analysed on a full night of polysomnography over the frontal, central
and parietal brain regions, and we measured their density, morphology and sigma-band power. White matter deterioration was
quantified using diffusion-weighted MRI, with which we performed both whole-brain voxel-wise analysis (Tract-Based Spatial
Statistics) and probabilistic tractography (with High Angular Resolution Diffusion Imaging) to target the thalamo-cortical tracts.
Group differences were assessed for all variables and correlations were performed separately in each group, corrected for age and
multiple comparisons. Surprisingly, although extensive white matter damage across the brain including all thalamo-cortical tracts
was evident in the brain-injured group, sleep spindles remained completely undisrupted when compared to a healthy control group.
In addition, almost all sleep spindle characteristics were not associated with the degree of white matter deterioration in the braininjured group, except that more white matter deterioration correlated with lower spindle frequency over the frontal regions. This
study highlights the resilience of sleep spindles to the deterioration of all white matter tracts critical to their existence, as they conserve normal density during non-rapid eye movement sleep with mostly unaltered morphology. We show that even with such a severe traumatic event, the brain has the ability to adapt or to withstand alterations in order to conserve normal sleep spindles
Cerebral white matter diffusion properties and freeâwater with obstructive sleep apnea severity in older adults
Characterizing the effects of obstructive sleep apnea (OSA) on the aging brain could be key in our understanding of neurodegeneration in this population. Our objective was to assess white matter properties in newly diagnosed and untreated adults with mild to severe OSA. Sixtyâfive adults aged 55 to 85 were recruited and divided into three groups: control (apneaâhypopnea index â€5/hr; n = 18; 65.2â±â7.2âyears old), mild (>5 to â€15 hr; n = 27; 64.2â±â5.3âyears old) and moderate to severe OSA (>15/hr; n = 20; 65.2â±â5.5âyears old). Diffusion tensor imaging metrics (fractional anisotropy (FA), axial diffusivity (AD), radial diffusivity, and mean diffusivity) were compared between groups with TractâBased Spatial Statistics within the white matter skeleton created by the technique. Groups were also compared for white matter hyperintensities volume and the freeâwater (FW) fraction. Compared with controls, mild OSA participants showed widespread areas of lower diffusivity (pâ<â.05 corrected) and lower FW fraction (pâ<â.05). Participants with moderate to severe OSA showed lower AD in the corpus callosum compared with controls (pâ<â.05 corrected). No betweenâgroup differences were observed for FA or white matter hyperintensities. Lower white matter diffusivity metrics is especially marked in mild OSA, suggesting that even the milder form may lead to detrimental outcomes. In moderate to severe OSA, competing pathological responses might have led to partial normalization of diffusion metrics
Examination of the association of sex and race/ethnicity with appearance concerns: A Scleroderma Patient-centered Intervention Network (SPIN) cohort study
Objective: Appearance concerns are common in systemic sclerosis (SSc) and have been linked to younger age and more severe disease. No study has examined their association with sex or race/ethnicity. Methods: SSc patients were sampled from the Scleroderma Patient-centered Intervention Network Cohort. Presence of appearance concerns was assessed with a single item, and medical and sociodemographic information were collected. Results: Of 644 patients, appearance concerns were present in 72%, including 421 of 565 women (75%), 42 of 79 men (53%), 392 of 550 patients who identified as White (71%), 35 of 41 who identified as Black (85%), and 36 of 53 who identified as another race/ethnicity (68%). In multivariate analysis, women had significantly greater odds of reporting appearance concerns than men (odds ratio (OR)=2.97, 95% confidence interval (CI)=1.78-4.95,
Altered resting-state functional connectivity patterns in late middle-aged and older adults with obstructive sleep apnea
IntroductionObstructive sleep apnea (OSA) is increasingly recognized as a risk factor for cognitive decline, and has been associated with structural brain alterations in regions relevant to memory processes and Alzheimerâs disease. However, it is unclear whether OSA is associated with disrupted functional connectivity (FC) patterns between these regions in late middle-aged and older populations. Thus, we characterized the associations between OSA severity and resting-state FC between the default mode network (DMN) and medial temporal lobe (MTL) regions. Second, we explored whether significant FC changes differed depending on cognitive status and were associated with cognitive performance.MethodsNinety-four participants [24 women, 65.7â±â6.9 years old, 41% with Mild Cognitive Impairment (MCI)] underwent a polysomnography, a comprehensive neuropsychological assessment and a resting-state functional magnetic resonance imaging (MRI). General linear models were conducted between OSA severity markers (i.e., the apnea-hypopnea, oxygen desaturation and microarousal indices) and FC values between DMN and MTL regions using CONN toolbox. Partial correlations were then performed between OSA-related FC patterns and (i) OSA severity markers in subgroups stratified by cognitive status (i.e., cognitively unimpaired versus MCI) and (ii) cognitive scores in the whole sample. All analyzes were controlled for age, sex and education, and considered significant at a pâ<â0.05 threshold corrected for false discovery rate.ResultsIn the whole sample, a higher apnea-hypopnea index was significantly associated with lower FC between (i) the medial prefrontal cortex and bilateral hippocampi, and (ii) the left hippocampus and both the posterior cingulate cortex and precuneus. FC patterns were not associated with the oxygen desaturation index, or micro-arousal index. When stratifying the sample according to cognitive status, all associations remained significant in cognitively unimpaired individuals but not in the MCI group. No significant associations were observed between cognition and OSA severity or OSA-related FC patterns.DiscussionOSA severity was associated with patterns of lower FC in regions relevant to memory processes and Alzheimerâs disease. Since no associations were found with cognitive performance, these FC changes could precede detectable cognitive deficits. Whether these FC patterns predict future cognitive decline over the long-term needs to be investigated
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