Microcirculation and Macrocirculation in Cardiac Surgical Patients

Background. The aim of our study was to investigate the relationship between microcirculatory alterations after open cardiac surgery, macrohemodynamics, and global indices of organ perfusion. Methods. Patients' microcirculation was assessed with near-infrared spectroscopy (NIRS) and the vascular occlusion technique (VOT). Results. 23 patients undergoing open cardiac surgery (11 male/12 female, median age 68 (range 28–82) years, EuroSCORE 6 (1–12)) were enrolled in the study. For pooled data, CI correlated with the tissue oxygen consumption rate as well as the reperfusion rate (r = 0.56, P < 0.001 and r = 0.58, P < 0.001, resp.). In addition, both total oxygen delivery (DO2, mL/min per m2) and total oxygen consumption (VO2, mL/min per m2) also correlated with the tissue oxygen consumption rate and the reperfusion rate. The tissue oxygen saturation of the thenar postoperatively correlated with the peak lactate levels during the six hour monitoring period (r = 0.50, P < 0.05). The tissue oxygen consumption rate (%/min) and the reperfusion rate (%/min), as derived from the VOT, were higher in survivors compared to nonsurvivors for pooled data [23 (4–54) versus 20 (8–38) P < 0.05] and [424 (27–1215) versus 197 (57–632) P < 0.01], respectively. Conclusion. Microcirculatory alterations after open cardiac surgery are related to macrohemodynamics and global indices of organ perfusion

Evidence of functional deficits at the single muscle fiber level in experimentally-induced renal insufficiency

Chronic kidney disease patients present with metabolic and functional muscle abnormalities, called uremic myopathy, whose mechanisms have not yet been fully elucidated. We investigated whether chronic renal insufficiency (CRI) affects skeletal muscle contractile properties at the cellular level. CRI was induced surgically in New Zealand rabbits (UREM), with sham-operation for controls (CON), and samples were collected at 3 months post-surgery, following euthanasia. All protocols had University Ethics approval following national and European guidelines. Sample treatments and evaluations were blinded. Maximal isometric force was assessed in 382 permeabilized psoas fibers (CON, n=142, UREM, n=240) initially at pH7, 10oC (‘standard’ conditions), in subsets of fibers in acidic conditions (pH6.2, 10oC) but also at near physiological temperature (pH7, 30oC and pH6.2, 30oC). CRI resulted in significant smaller average CSA (~11%) for UREM muscle fibers (vs CON, P<0.01). At standard conditions, UREM fibers produced lower absolute and specific forces (i.e. normalized force per fiber CSA) (vs CON, P<0.01); force increased in 30oC for both groups (P<0.01), but the disparity between UREM and CON remained significant. Acidosis significantly reduced force (vs pH7, 10oC P<0.01), similarly in both groups (in UREM by -48% and in CON by -43%, P>0.05). For the first time, we give evidence that CRI can induce significant impairments in single psoas muscle fibers force generation, only partially explained by fiber atrophy, thus affecting muscle mechanics at the cellular level

Combined Investigation of Indoor Environmental Conditions and Energy Performance of an Aquatic Center

This study presents a combined investigation of indoor environmental conditions and energy performance in a naturally ventilated aquatic center in Western Macedonia, Greece. The experimental analysis was conducted over nine days during the summer. The operative temperature exceeded the acceptable limits for most days, while the same can be stated for the PMV, demonstrating high indoor air and radiant temperature values. The weaknesses of applying the above thermal comfort models in this type of buildings are also discussed. Relative humidity presents generally acceptable values during operation time, indicating the contribution of natural ventilation; nevertheless, as demonstrated by the CO2 concentration values, the ventilation rate can be further increased. On the basis of the above findings, a renovation scenario has been formulated, considering the installation of an air-conditioning system, as well as specific interventions, towards the improvement of the building envelope and systems’ thermal performance. A dynamic energy analysis, based on Energy Plus software, had energy savings of 9%, noting the considerable upgrade of indoor conditions. Overall, the proposed combined investigation approach proved to be suitable for such a complicated problem, as the one of indoor aquatic centers, presenting a high generalization potential

Combined Investigation of Indoor Climate Parameters and Energy Performance of a Winery

Wineries present significant interest on a research level, combining Indoor Air Quality (IAQ) issues related with substances emitted through the wine production, as well as the need for minimizing conventional energy consumption (optimizing energy performance). In the proposed work, experimental and theoretical analyses are presented which aim to achieve both targets, that of improved indoor climate and energy performance. An extensive measurement campaign was implemented, regarding indoor climate thermal parameters, as well as concentration of substances (CO2, VOCs, NO2) affecting IAQ. The results of the parameters were exploited for the assessment of indoor climate; moreover, data from indoor thermal parameters together with values of specific parameters related to the efficiency of the individual devices were utilized in the development of the energy model. The model was used to formulate and evaluate proposals for reducing the energy consumption of the winery. The proposals include the use of Renewable Energy Sources (RES) and, in particular, the installation of a photovoltaic array on the roof of the premises. Finally, an economic and technical study was carried out to determine the performance of the suggested interventions and the expected payback period

Combined Investigation of Indoor Climate Parameters and Energy Performance of a Winery

Wineries present significant interest on a research level, combining Indoor Air Quality (IAQ) issues related with substances emitted through the wine production, as well as the need for minimizing conventional energy consumption (optimizing energy performance). In the proposed work, experimental and theoretical analyses are presented which aim to achieve both targets, that of improved indoor climate and energy performance. An extensive measurement campaign was implemented, regarding indoor climate thermal parameters, as well as concentration of substances (CO2, VOCs, NO2) affecting IAQ. The results of the parameters were exploited for the assessment of indoor climate; moreover, data from indoor thermal parameters together with values of specific parameters related to the efficiency of the individual devices were utilized in the development of the energy model. The model was used to formulate and evaluate proposals for reducing the energy consumption of the winery. The proposals include the use of Renewable Energy Sources (RES) and, in particular, the installation of a photovoltaic array on the roof of the premises. Finally, an economic and technical study was carried out to determine the performance of the suggested interventions and the expected payback period

The development of a chatbot using Convolutional Neural Networks

Chatbots are artificial intelligence systems that comprehend the intent, context, and sentiment of the user, interact properly with them leading to an increased development of their creation, the past few years. In this study, Convolutional Neural Networks (CNNs) are applied as the classifier and some specific tools for tokenization are used for the creation of a chatbot. Taking into account that it is difficult to apply any algorithm in text, we use a technique called “Word Embedding”, which converts a text into numbers in order to run text processing. Specifically, “Word2Vec” Word Embedding technique was applied. AlexNet, LeNet5, ResNet and VGGNet CNN architectures were utilised. These architectures were compared for their accuracy, f1 score, training time and execution time. The results obtained highlighted that there were significant differences in the performance of the architectures applied. The most preferable architecture of our study was LeNet-5 having the best accuracy compared to other architectures, the fastest training time, and the least losses whereas it was not very accurate on smaller datasets such as our Test Set. Limitations and directions for future research are also presented

Air Quality Versus Perceived Comfort and Health in Office Buildings at Western Macedonia Area, Greece during the Pandemic Period

This study investigated the indoor environment quality (IEQ) of eight office buildings of interest due to: (a) their location at the region of Western Macedonia, Greece, which is an area characterized by aggravated air quality and is currently in a transition phase because of changes in the energy production strategy to reduce the use of lignite as an energy fuel; and (b) the survey’s timing, characterized by new working conditions implemented during the COVID-19 pandemic period. In-site measurements were performed to identify the indoor air pollutants to which the occupants were exposed, while questionnaires were collected regarding the participants’ perception of the working environment conditions, indoor air quality, and health symptoms. The statistical analysis results showed that the most-reported health symptoms were headache, dry eyes, and sneezing. The acceptance of new working conditions showed a significant correlation with their overall comfort and health perception. Occupants in offices with higher pollutant concentrations, such as NO2, benzene and toluene, were more likely to report health symptoms. The evaluation of the plausible health risks for the occupants of the buildings with carcinogenic and no-cancer models showed that health problems could exist despite low pollutant concentration levels