Parabolic Trough System Operating with Nanofluids: Comparison with the Conventional Working Fluids and Influence on the System Performance

Abstract To analyse the behaviour of a parabolic trough operating with nanofluids, and compare its performance to the more traditional ones using oil, a model for the thermal analysis of the system has been developed and implemented in Matlab. The simulations have been performed for a suspension of Al 2 O 3 in synthetic oil and its characteristics compared to the corresponding basic liquid used by itself. The string has been assumed to have a length of 100 m and a concentrating surface area of 550 m 2 . The simulations have been carried out for different DNI (Direct normal irradiance) and variable mass flow, ensuring a temperature at the collector outlet below 400C. For a proper comparison, the following variables and efficiency indicators have been checked: power output, pumping power, thermal efficiency and overall efficiency of the parabolic trough system

Computational Fluid Dynamics Simulations to Evaluate the Performance Improvement for Air-cooler Equipped with a Water Spray System

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Nutritional status and body composition by bioelectrical impedance vector analysis : a cross sectional study in mild cognitive impairment and Alzheimer's disease

Aims Analysis of nutritional status and body composition in Alzheimer's disease (AD) and Mild Cognitive Impairment (MCI). Methods A cross-sectional study was performed in a University-Hospital setting, recruiting 59 patients with AD, 34 subjects with MCI and 58 elderly healthy controls (HC). Nutritional status was assessed by anthropometric parameters (body mass index; calf, upper arm and waist circumferences), Mini Nutritional Assessment (MNA) and body composition by bioelectrical impedance vector analysis (BIVA). Variables were analyzed by analysis of variance and subjects were grouped by cognitive status and gender. Results Sociodemographic variables did not differ among the three groups (AD, MCI and HC), except for females' age, which was therefore used as covariate in a general linear multivariate model. MNA score was significantly lower in AD patients than in HC; MCI subjects achieved intermediate scores. AD patients (both sexes) had significantly (p<0.05) higher height-normalized impedance values and lower phase angles (body cell mass) compared with HC; a higher ratio of impedance to height was found in men with MCI with respect to HC. With BIVA method, MCI subjects showed a significant displacement on the RXc graph on the right side indicating lower soft tissues (Hotelling's T2 test: men = 10.6; women = 7.9;p < 0,05) just like AD patients (Hotelling's T2 test: men = 18.2; women = 16.9; p<0,001). Conclusion Bioelectrical parameters significantly differ from MCI and AD to HC; MCI showed an intermediate pattern between AD and HC. Longitudinal studies are required to investigate if BIVA could reflect early AD-changes in body composition in subjects with MCI

Weight loss predicts progression of mild cognitive impairment to Alzheimer&apos;s disease

Background Weight loss is common in people with Alzheimer's disease (AD) and it could be a marker of impending AD in Mild Cognitive Impairment (MCI) and improve prognostic accuracy, if accelerated progression to AD would be shown. Aims To assess weight loss as a predictor of dementia and AD in MCI. Methods One hundred twenty-five subjects with MCI (age 73.8 \ub1 7.1 years) were followed for an average of 4 years. Two weight measurements were carried out at a minimum time interval of one year. Dementia was defined according to DSM-IV criteria and AD according to NINCDS-ADRDA criteria. Weight loss was defined as a 654% decrease in baseline weight. Results Fifty-three (42.4%) MCI progressed to dementia, which was of the AD-type in half of the cases. Weight loss was associated with a 3.4-fold increased risk of dementia (95% CI = 1.5-6.9) and a 3.2-fold increased risk of AD (95% CI = 1.4-8.3). In terms of years lived without disease, weight loss was associated to a 2.3 and 2.5 years earlier onset of dementia and AD. Conclusions Accelerated progression towards dementia and AD is expected when weight loss is observed in MCI patients. Weight should be closely monitored in elderly with mild cognitive impairment

High blood pressure and other vascular risk factors in mild cognitive impairment subtypes

Introduction. Mild cognitive impairment (MCI) is a syndrome featuring cognitive decline not interfering with activities of daily life. Different MCI subtypes have been described, including MCI with only memory impairment (A-MCI), MCI with involvement of a single non-memory domain (NA-MCI) and MCI with multiple-domain impairment (MD-MCI). From a prognostic point of view A-MCI is considered early Alzheimer\u2019s Disease (AD), while NA-MCI and MD-MCI are thought to be heterogeneous conditions, underlying different pathological substrate including vascular pathology. Vascular risk factors (VRFs) have been identified as risk factors for MCI, but little is known about the role of VRFs in MCI subtypes. Aim. to investigate the association of different VRFs in MCI subtypes comparing the findings of subject with A-MCI with those of NA-MCI and MD-MCI. Methods. We performed a cross-sectional analysis of MCI population evaluated in a University-Hospital setting. Two hundred and fourteen subjects with MCI were included in the study: 39 with A-MCI, 28 with NA-MCI and 147 with MD-MCI. There were no significant differences among group in age (years: 74.3\ub18, 73.8\ub16 75.2\ub16.7, respectively), gender (female 51%, 64%, 54%) cognition (MMSE 25.7\ub12.5, 24.8\ub14.4, 24.8\ub12.9), mood (GDS 9.7\ub15.9, 10.5\ub16.3, 10.9\ub16.5), Hachinski ischemic score (2.2\ub10.9, 2.6\ub11.6, 2.6\ub11.1) and comorbilities as assessed with CIRS (0.43\ub10.22, 0.58\ub10.28, 0.51\ub10.27). Education was slightly lower in NA-MCI (5.7\ub12.7 years) with respect to A-MCI (8.9\ub14.2 years, p=0.007) Multinomial logistic regression analyses, adjusted for demographic variables when appropriate, were performed to evaluate the weight of VRFs in the development of the various MCI subtypes. Results. Hypertension revealed a stronger association with SD-MCI (OR 3.47; 95%CI 1.13 \u2013 10.67) and MD-MCI (OR 7.81; 95%CI 3.48 \u2013 17.50) respect to A-MCI .Hyperlipemia resulted the most frequent VRF in all MCI subgroups (81.8%, 76% and 70.8% in A-, NA- and MD-MCI respectively), without significant differences among groups. Discussion. Hypertension was associated with increased risk of all MCI subtypes, but the association was stronger with NA-MCI and MD-MCI. This association could reflect the role of high blood pressure in vascular cognitive impairment. The high frequency of hyperlipemia in all MCI subgroups, could reflect both the role of cholesterol metabolism in AD pathogenesis and the role of atherosclerosis in the development of vascular cognitive impairment. Due to the cross-sectional nature of this study, a relationship between VRFs and subsequent evolution in different subtypes of dementia could only be hypothesized

The Luigi Sacco Hospital VAS-COG stroke care pathway: A five-year experience

Background: Psycho-cognitive consequences are a frequent cause of disability in stroke survivors but are often underdiagnosed also because of lack of services dedicated to these aspects. We started assessing systematically cognitive and behavioral functions in acute stroke patients and to follow them up. Here, we report a retrospective analysis of the organization of the Sacco VAS-COG stroke care pathway and the refinements implemented during 5 years of activity. Methods: The protocol includes baseline collection of clinical history, general and neurologic examinations, functional, neuropsychological, and neuroimaging assessment. At follow-up, a diagnosis of cognitive decline was made based on best clinical judgment in the first period (January 2018 to May 2019, namely VAS-COG protocol 1.0) and then based on an extensive neuropsychological battery (May 2019 to January 2023, namely VASCOG protocol 2.0); psychiatric and behavioral disturbances are investigated through suitable scales. Results: From January 2018 to December 2022, 834 patients (mean age 76±13.6 years; 46.6 % females) with acute cerebrovascular events were admitted to the stroke unit, mostly (80 %) for ischemic strokes. Pre-event cognitive impairment was not assessable in 78 patients (9.3 %) because no reliable informant was present and was reported in 327/756 (43 %) patients. During follow-up, post-stroke cognitive impairment was detected in 124/217 (57.1 %) patients in VAS-COG protocol 1.0 and in 137/201(68.2 %) patients in VAS-COG protocol 2.0, while 95/218 (43.2 %) patients were found to be depressed and patients presented on average 2.5 neuropsychiatric symptoms on Neuropsychiatric Inventory-questionnaire. Conclusions: The VAS-COG stroke care pathway represents a model for patients and for their families

Physical activity reduces the risk of dementia in MCI subjects : a cohort study

Background: Leisure activities, particularly exercise, play a protective role against dementia in healthy people, but it is unknown if this protective effect could be generalized to subjects with mild cognitive impairment (MCI). Objective: To investigate the influence of leisure activities on the risk of progression of MCI to dementia. Methods: 176 MCI subjects attending a memory clinic underwent a standardized lifestyle questionnaire between October 2007 and May 2010. Social, cognitive, and physical scores were derived based on the assiduity of interpersonal contacts and on the frequency of participation in individual leisure activities. Subjects were requested to return every 12 months for dementia surveillance. The outcome measure was the risk of dementia associated with social, cognitive, and physical scores. Results: Over a median follow-up time of 2.59 year, 92 (52.2%) MCI subjects developed dementia. Subjects with physical scores in the highest third had a lower risk (HR 0.44; 95% CI 0.23-0.85) of dementia compared with those in the lowest third. No association was found between cognitive or social scores and the risk of dementia. Conclusion: To our knowledge, this is the first prospective clinical study which demonstrates that high levels of participation in physical leisure activities are associated with reduced risk of dementia in subjects with MCI. In line with findings coming from community-based studies on healthy elderly, our finding suggests that the protective role of exercise against the development of dementia can be generalized to MCI subjects seen in clinical practice. Clinicians should encourage MCI subjects to participate in physical leisure activities

Self-Awareness for Memory Impairment in Amnestic Mild Cognitive Impairment: A Longitudinal Study

Aim: To assess memory impairment insight as a predictor of dementia and Alzheimer's disease (AD) in amnestic mild cognitive impairment (MCI). Methods: To verify whether the awareness of memory impairment assessed by Geriatric Depression Scale (GDS) was associated with the risk of progression to dementia and AD in a cohort of MCI, we used a Cox regression model adjusted for age, sex, education, subtypes of amnestic MCI, Mini-Mental State Examination, Cumulative Illness Rating Scale severity index, and apolipoprotein E genotype. Results: During a follow-up of 27.7 (20.8) months, 205 (63.3%) of 324 patients with amnestic MCI progressed to dementia, including 141 to AD. No association was found in the unadjusted, partially adjusted (for sociodemographic variables), and fully adjusted multivariate Cox analysis between the awareness of memory impairment and the progression to dementia and AD. Discussion: Awareness or anosognosia of memory deficits, identified by GDS, is not useful to predict progression to dementia of patients with amnestic MCI

Neuropsychological screening in the acute phase of cerebrovascular diseases

Introduction: Cognitive impairment is a common and disabling consequence of stroke. Its prevalence, the best way to screen for it in the acute setting, and its relation with premorbid status have not been thoroughly clarified. Materials and methods: Ischemic and hemorrhagic stroke patients admitted to our stroke unit underwent a baseline assessment that included a clinical and neuroimaging assessment, two cognitive tests (clock-drawing test, CDT; Montreal Cognitive Assessment-Basic, MoCA-B) and measures of premorbid function (including the Clinical Dementia Rating Scale). A follow-up examination was repeated 3-4&nbsp;months after the acute event. Results: Two hundred and twenty-three patients (52.5% women, mean age&nbsp;\ub1&nbsp;SD 75.8&nbsp;years&nbsp;\ub1&nbsp;12.3) were evaluated. Prestroke cognitive impairment was present in 91 patients (40.8%). At follow-up, the prevalence of cognitive impairment was 49%, while its incidence among patients who did not have any prestroke cognitive impairment was 38.8%. Of the originally admitted 223 patients (71 were lost to follow-up), only 60 (26.9%) were still cognitively intact at follow-up. On regression analysis, age and baseline CDT were associated with worsening of cognitive status at follow-up. In patients without cognitive impairment at baseline, a cutoff of 23 for MoCA-B and of 8.7 for CDT scores predicted the diagnosis of post-stroke cognitive impairment with sufficient accuracy. Discussion and conclusion: Prestroke and post-stroke cognitive impairment affect a large proportion of patients with stroke. Our findings suggest that a neuropsychological screening during the acute phase might be predictive of the development of post-stroke cognitive impairment