...the hasty identification of malnutrition using body mass index (BMI) or anthropometric measures or laboratory parameters after the acute event is fundamental to avoid poor outcomes 10, 14, 15. In ...the acute stage of stroke, dysphagia occurs in 30–50% of the patients and leads to a 12-fold increase in developing aspiration pneumonia and subsequent malnutrition 16, 23, 24. ...the presence of cognitive impairments, visual, language, and speech deficits can hinder effective communication about food preference and satiety leading to malnutrition 14. In the absence of infection and inflammation, serum albumin level can give a fair estimate of the nutritional status 14. ...CRP has been found to predict vasospasms and long-term outcome in SAH patients 33, 34. According to several studies 11, 39, 40, being at high risk of malnutrition, as assessed by MUST, is a significant independent predictor of mortality, length of hospitalization, and hospitalization costs at 6 months post-stroke.
Angiogenesis, the growth of new blood vessels, is a natural defense mechanism helping to restore oxygen and nutrient supply to the affected brain tissue following an ischemic stroke. By stimulating ...vessel growth, angiogenesis may stabilize brain perfusion, thereby promoting neuronal survival, brain plasticity, and neurologic recovery. However, therapeutic angiogenesis after stroke faces challenges: new angiogenesis-induced vessels have a higher than normal permeability, and treatment to promote angiogenesis may exacerbate outcomes in stroke patients. The development of therapies requires elucidation of the precise cellular and molecular basis of the disease. Microenvironment homeostasis of the central nervous system is essential for its normal function and is maintained by the blood-brain barrier (BBB). Tight junction proteins (TJP) form the tight junction (TJ) between vascular endothelial cells (ECs) and play a key role in regulating the BBB permeability. We demonstrated that after stroke, new angiogenesis-induced vessels in peri-infarct areas have abnormally high BBB permeability due to a lack of major TJPs in ECs. Therefore, promoting TJ formation and BBB integrity in the new vessels coupled with speedy angiogenesis will provide a promising and safer treatment strategy for improving recovery from stroke. Pericyte is a central neurovascular unite component in vascular barriergenesis and are vital to BBB integrity. We found that pericytes also play a key role in stroke-induced angiogenesis and TJ formation in the newly formed vessels. Based on these findings, in this article, we focus on regulation aspects of the BBB functions and describe cellular and molecular special features of TJ formation with an emphasis on role of pericytes in BBB integrity during angiogenesis after stroke.
Brought to life more than half a century ago and successfully applied for high-value petrochemical intermediates production, nickel-catalyzed olefin oligomerization is still a very dynamic topic, ...with many fundamental questions to address and industrial challenges to overcome. The unique and versatile reactivity of nickel enables the oligomerization of ethylene, propylene, and butenes into a wide range of oligomers that are highly sought-after in numerous fields to be controlled. Interestingly, both homogeneous and heterogeneous nickel catalysts have been scrutinized and employed to do this. This rare specificity encouraged us to interlink them in this review so as to open up opportunities for further catalyst development and innovation. An in-depth understanding of the reaction mechanisms in play is essential to being able to fine-tune the selectivity and achieve efficiency in the rational design of novel catalytic systems. This review thus provides a complete overview of the subject, compiling the main fundamental/industrial milestones and remaining challenges facing homogeneous/heterogeneous approaches as well as emerging catalytic concepts, with a focus on the last 10 years.
Alteration of gut microbiome composition has been linked to cardiovascular diseases. To identify specific bacterial communities associated with coronary artery diseases (CAD), we conducted a ...case-control study with 53 advanced CAD patients and 53 age-, sex-, race-, and BMI-matched controls. V3-V5 regions of the 16S rDNA from the fecal gut material were analyzed to compare the gut microbiome composition between CAD patients and controls. The alpha diversity, including Chao-1, Shannon-index, and the number of observed taxonomy units were significantly decreased in CAD patients indicating, decreased richness and evenness of gut microbiome. Among 23 different abundant taxa at the genus level, 12 taxa belonged to Lachnospiraceae family, which are known to produce butyrate. Further, we identified five taxa which showed more than two log-fold changes with maximum proportion >0.002, including Ruminococcus gnavus, Lachnospiraceae anaerosporobacter, Lachnospiraceae NK4B4 group, Lachnospiraceae UCG-004, and Ruminococcus gauvreauii. After adjustment for coronary risk factors (diabetes mellitus and dyslipidemia), decreased relative abundance of Lachnospiraceae NK4B4 group and Ruminococcus Gauvreauii and increased relative abundance of Ruminococcus gnavus were associated with the presence of advanced CAD. The observed differences in taxa between CAD patients and controls in this study may provide insight into the link between the gut microbiome and CAD.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
•Subcooled flow boiling heat transfer measurements were made in a 6 mm ID tube at various gravity levels, flow rates, heat fluxes, and subcoolings using temperature sensitive paints to obtain local ...heat transfer.•The average heat transfer coefficient typically increased with heat flux, mass flux, and absolute gravity level.•In microgravity, the lack of mixing at low heat fluxes due to the absence of natural convection and bubble slip velocity resulted in a decrease in heat transfer coefficient compared to downward and upward conditions.•Mechanisms by which heat is transferred under various conditions are discussed.
Subcooled flow boiling measurements using HFE-7000 were obtained in a vertical 6 mm ID sapphire tube during upward and downward flow at various gravity levels including hypergravity and microgravity. Temperature sensitive paint (TSP) applied to the inside of the tube was used to measure time and space resolved temperature and heat transfer distributions at the wall–fluid interface, and this data along with flow visualization were used to characterize the heat transfer for different flow patterns. Time-averaged heat transfer coefficients were compared at nine gravity levels, four mass fluxes, six heat fluxes, and two subcoolings. The average heat transfer coefficient typically increased with heat flux, mass flux, and absolute gravity level. In microgravity, the lack of mixing at low heat fluxes due to the absence of natural convection and bubble slip velocity resulted in a decrease in heat transfer coefficient compared to downward and upward conditions. The heat transfer was strongly dependent on the flow regime, causing certain data points at high mass flux or low gravity to deviate from the typical trends due to deactivation of nucleation sites. The heat transfer coefficient became less dependent on gravity as the mass flux and heat flux increased. Flow regimes were very sensitive to the competition between buoyancy and inertial forces, which in turn affected the heat transfer. Mechanisms by which heat is transferred under various conditions are discussed.
In elderly populations, frailty is associated with higher mortality risk. Although many frailty scores (FS) have been proposed, no single score is considered the gold standard. We aimed to evaluate ...the agreement between a wide range of FS in the English Longitudinal Study of Ageing (ELSA). Through a literature search, we identified 35 FS that could be calculated in ELSA wave 2 (2004-2005). We examined agreement between each frailty score and the mean of 35 FS, using a modified Bland-Altman model and Cohen's kappa (κ). Missing data were imputed. Data from 5,377 participants (ages ≥60 years) were analyzed (44.7% men, 55.3% women). FS showed widely differing degrees of agreement with the mean of all scores and between each pair of scores. Frailty classification also showed a very wide range of agreement (Cohen's κ = 0.10-0.83). Agreement was highest among "accumulation of deficits"-type FS, while accuracy was highest for multidimensional FS. There is marked heterogeneity in the degree to which various FS estimate frailty and in the identification of particular individuals as frail. Different FS are based on different concepts of frailty, and most pairs cannot be assumed to be interchangeable. Research results based on different FS cannot be compared or pooled.
Toward a Circuit Theory of Communication Ivrlac, Michel T; Nossek, Josef A
IEEE transactions on circuits and systems. I, Regular papers,
07/2010, Letnik:
57, Številka:
7
Journal Article
Recenzirano
Electromagnetic field theory provides the physics of radio communications, while information theory approaches the problem from a purely mathematical point of view. While there is a law of ...conservation of energy in physics, there is no such law in information theory. Consequently, when, in information theory, reference is made (as it frequently is) to terms like energy, power, noise, or antennas, it is by no means guaranteed that their use is consistent with the physics of the communication system. Circuit theoretic multiport concepts can help in bridging the gap between the physics of electromagnetic fields and the mathematical world of information theory, so that important terms like energy or antenna are indeed used consistently through all layers of abstraction. In this paper, we develop circuit theoretic multiport models for radio communication systems. To demonstrate the utility of the circuit theoretic approach, an in-depth analysis is provided on the impact of impedance matching, antenna mutual coupling, and different sources of noise on the performance of the communication system. Interesting insights are developed about the role of impedance matching and the noise properties of the receive amplifiers, as well as the way array gain and channel capacity scale with the number of antennas in different circumstances. One particularly interesting result is that, with arrays of lossless antennas that receive isotropic background noise, efficient multistreaming can be achieved no matter how densely the antennas are packed.
The understanding of interactions between electrons and phonons in atomically thin heterostructures is crucial for the engineering of novel two-dimensional devices. Electron-phonon (el-ph) ...interactions in layered materials can occur involving electrons in the same layer or in different layers. Here we report on the possibility of distinguishing intralayer and interlayer el-ph interactions in samples of twisted bilayer graphene and of probing the intralayer process in graphene/h-BN by using Raman spectroscopy. In the intralayer process, the el-ph scattering occurs in a single graphene layer and the other layer (graphene or h-BN) imposes a periodic potential that backscatters the excited electron, whereas for the interlayer process the el-ph scattering occurs between states in the Dirac cones of adjacent graphene layers. Our methodology of using Raman spectroscopy to probe different types of el-ph interactions can be extended to study any kind of graphene-based heterostructure.
Purpose: This one-group pretest−posttest, designed within a subject study, looks to compare the effects of an outdoor nature walk (ONW) to those of a virtual nature walk (VRW) on memory and cognitive ...function. Implications are discussed for education as well as for the world of virtual reality. Methods: Sixty-four healthy university students were asked to complete an ONW and a VRW, which was created using 3D video of the same nature trail used for the ONW. The VRW condition involved a five-minute walk on a treadmill, while wearing a virtual reality mask (Oculus, San Francisco, USA) that projected a previously recorded three-dimensional capture of the same nature walk they experienced outdoors. Both experimental conditions lasted approximately 5 min and were counterbalanced between participants. A Digit Span Test (Digit) for working memory and a Trail Test (TMT) for executive function were administered to all study participants, immediately before and after each type of walk. Results: For executive function testing (Trail Making Test), our results demonstrate that both the ONW and VRW condition improved the TMT time, when compared to a baseline (ONW 37.06 ± 1.31 s vs. 31.75 ± 1.07 s, p < 0.01 and VRW 36.19 ± 1.18 s vs. 30.69 ± 1.11 s, p < 0.01). There was no significant difference between the ONW and VRW groups. Similarly, for the Digit memory task, both conditions improved compared to the baseline (ONW 54.30 ± 3.01 vs. 68.4 ± 2.66, p < 0.01 and VRW 58.1 ± 3.10 vs. 67.4 ± 2.72, p < 0.01). There was a difference at the baseline between the ONW and VRW conditions (54.3 ± 3.01 vs. 58.1 ± 3.10, p < 0.01), but this baseline difference in memory performance was no longer significant post exercise, between groups at follow-up (68.4 ± 2.66 vs. 67.4 ± 2.72, p < 0.08). Conclusions: Our results suggest that both a virtual reality protocol and a nature walk can have positive outcomes on memory and executive function in younger adults.
OBJECTIVE
Frailty is a dynamic state of vulnerability in the elderly. We examined whether individuals with overt diabetes or higher levels of HbA1c or fasting plasma glucose (FG) experience different ...frailty trajectories with aging.
RESEARCH DESIGN AND METHODS
Diabetes, HbA1c, and FG were assessed at baseline, and frailty status was evaluated with a 36-item frailty index every 2 years during a 10-year follow-up among participants from the English Longitudinal Study of Ageing (ELSA). Mixed-effects models with age as time scale were used to assess whether age trajectories of frailty differed as a function of diabetes, HbA1c, and FG.
RESULTS
Among 5,377 participants (median age interquartile range 70 65, 77 years, 45% men), 35% were frail at baseline. In a model adjusted for sex, participants with baseline diabetes had an increased frailty index over aging compared with those without diabetes. Similar findings were observed with higher levels of HbA1c, while FG was not associated with frailty. In a model additionally adjusted for income, social class, smoking, alcohol, and hemoglobin, only diabetes was associated with an increased frailty index. Among nonfrail participants at baseline, both diabetes and HbA1c level were associated with a higher increased frailty index over time.
CONCLUSIONS
People with diabetes or higher HbA1c levels at baseline had a higher frailty level throughout later life. Nonfrail participants with diabetes or higher HbA1c also experienced more rapid deterioration of frailty level with aging. This observation could reflect a role of diabetes complications in frailty trajectories or earlier shared determinants that contribute to diabetes and frailty risk in later life.
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