Low Levels of Selenoprotein P Are Associated With Cognitive Impairment in Patients Hospitalized for Heart Failure.

BACKGROUND: Selenoprotein P (SELENOP) is a transporter for selenium and has been shown to protect selenium-status maintenance in the brain against deficiency and to support neuronal development, neurogenesis and neurocognitive function. Selenium deficiency has previously been associated with cognitive impairment in various populations, but no studies have been carried out in subjects with heart failure (HF). PURPOSE: To explore whether SELENOP deficiency in subjects with acute HF is associated with cognitive impairment. METHODS: Plasma SELENOP, as measured by an immunoassay analysis, is a well-validated marker of plasma selenium status and has the benefit of providing information on the bioavailable fraction of selenium to preferentially supplied cells equipped with receptors for SELENOP uptake. SELENOP was measured in 320 subjects hospitalized for HF. Of the subjects, 187 also underwent 4 cognitive tests assessing global cognitive function: Montreal Cognitive Assessment (MoCA); information processing (Symbol Digit Modalities Test [SDMT]); visual attention and task switching (Trailmaking Test A [TMT-A]); and executive speed (A Quick Test of Cognitive Speed [AQT] form and color). Appropriate cutoffs were used for each cognitive test to define cognitive impairment. Cross-sectional associations between SELENOP concentrations and cognitive impairment, as defined by each cognitive test, were explored using multivariable logistic models. Further, multivariable logistic models exploring associations between selenium deficiency, defined as the lowest quartile of SELENOP levels, and cognitive impairment, defined by each cognitive test, were carried out. RESULTS: The 187 participants had a mean age of 73 (± 11.9) years; 31% were female and had a mean body mass index of 28.1 (± 5.6) kg/m2. Each 1 standard deviation increment in SELENOP concentrations was associated with lower odds of cognitive impairment, defined as a MoCA cut-off score < 23 (odds ratio [OR] 0.60; 95% CI 0.40-0.91; P = 0.017). Further, SELENOP concentrations in the lowest quartile (≤ 2.3 mg/L) were associated with cognitive impairment as measured by MoCA (OR 3.10; 95% CI 1.38-6.97; P = 0.006), SDMT (OR 2.26; 95% CI 1.10-4.67; P = 0.027) and TMT-A (OR 3.40; 95% CI 1.47-7.88; P = 0.004) but not by AQT form and color. CONCLUSIONS: In subjects admitted for HF, higher SELENOP concentrations were associated with better performance on the MoCA test, reflecting global cognition, and SELENOP deficiency was associated with cognitive impairment as defined by 3 cognitive tests.

Structured diabetes care routines in cardiac rehabilitation are associated with increased diabetes detection and improved treatment after myocardial infarction: a nationwide observational study.

BACKGROUND: Despite the detrimental impact of abnormal glucose metabolism on cardiovascular prognosis after myocardial infarction (MI), diabetes is both underdiagnosed and undertreated. We investigated associations between structured diabetes care routines in cardiac rehabilitation (CR) and detection and treatment of diabetes at one-year post-MI. METHODS: Center-level data was derived from the Perfect-CR survey, which evaluated work routines applied at Swedish CR centers (n = 76). Work routines involving diabetes care included: (1) routine assessment of fasting glucose and/or HbA1c, (2) routine use of oral glucose tolerance test (OGTT), (3) having regular case rounds with diabetologists, and (4) whether glucose-lowering medication was adjusted by CR physicians. Patient-level data was obtained from the national MI registry SWEDEHEART (n = 7601, 76% male, mean age 62.6 years) and included all post-MI patients irrespective of diabetes diagnosis. Using mixed-effects regression we estimated differences between patients exposed versus. not exposed to the four above-mentioned diabetes care routines. Outcomes were newly detected diabetes and the proportion of patients receiving oral glucose-lowering medication at one-year post-MI. RESULTS: Routine assessment of fasting glucose/HbA1c was performed at 63.2% (n = 48) of the centers, while 38.2% (n = 29) reported using OGTT for detecting glucose abnormalities. Glucose-lowering medication adjusted by CR physicians (n = 13, 17.1%) or regular case rounds with diabetologists (n = 7, 9.2%) were less frequently reported. In total, 4.0% of all patients (n = 304) were diagnosed with diabetes during follow-up and 17.9% (n = 1361) were on oral glucose-lowering treatment one-year post-MI. Routine use of OGTT was associated with a higher rate of newly detected diabetes at one-year (risk ratio [95% confidence interval]: 1.62 [1.26, 1.98], p = 0.0007). At one-year a higher proportion of patients were receiving oral glucose-lowering medication at centers using OGTT (1.22 [1.07, 1.37], p = 0.0046) and where such medication was adjusted by CR physicians (1.31 [1.06, 1.56], p = 0.0155). Compared to having none of the structured diabetes care routines, the more routines implemented the higher the rate of newly detected diabetes (from 0 routines: 2.7% to 4 routines: 6.3%; p for trend = 0.0014). CONCLUSIONS: Having structured routines for diabetes care implemented within CR can improve detection and treatment of diabetes post-MI. A cluster-randomized trial is warranted to ascertain causality.

Ventricular-arterial coupling and cardiovascular risk among young adults: The African-PREDICT study.

Ventricular-arterial coupling (VAC) has independent diagnostic and prognostic value for cardiovascular (CV) risk stratification, but studies on its association with anthropometric and CV factors are sparse in young individuals without overt CV disease. We aim to provide descriptive data regarding VAC and its associations with CV risk factors in young adults without overt CV disease. For 631 (mean age, 24 ± 3 yr; 51% female) individuals, VAC was determined by carotid-femoral pulse wave velocity (PWV)/global longitudinal strain (GLS). Multivariable logistic and linear regression models were performed to explore the association between PWV/GLS and CV risk factors. A P-value < 0.05 was considered statistically significant. The mean PWV/GLS was 0.33 ± 0.07 m/s%. Higher ratios of PWV/GLS associated with older age, male sex, and a higher prevalence of CV risk factors (i.e., higher blood pressure, prevalent hypertension, higher waist circumference, active smoking, higher plasma triglycerides, lower high-density lipoprotein cholesterol, and an adverse urine albumin/creatinine ratio). Furthermore, higher PWV/GLS was associated with echocardiographic measures such as lower ejection fraction and higher left ventricle mass index. In expanded logistic regression models, higher ratios of PWV/GLS were significantly associated with the prevalence of active smoking [odds ratio (OR), 1.88; confidence interval (CI) 1.36-2.58, P < 0.001] and hypertension (OR 1.98; CI 1.40-2.80, P < 0.001). We demonstrated that worse VAC reflected by higher values of PWV/GLS are significantly associated with CV risk factors in young adults. The results suggest that PWV/GLS might serve as a tool to improve the profiling of cardiovascular risk in young adults.NEW & NOTEWORTHY Assessing VAC is especially useful in heart failure and valvular heart disease, but less is known about VAC in the pathophysiology of CV disease risk in younger individuals. In young individuals without overt CV disease, we showed descriptive data regarding VAC, determined by PWV/GLS ratio, and explored the associations of VAC with clinical CV disease risk factors. Worse VAC, reflected by higher values of PWV/GLS, associated with high blood pressure and smoking in young adults.

The complexity of kidney disease and diagnosing it - cystatin C, selective glomerular hypofiltration syndromes and proteome regulation.

Estimation of kidney function is often part of daily clinical practice, mostly done by using the endogenous glomerular filtration rate (GFR)-markers creatinine or cystatin C. A recommendation to use both markers in parallel in 2010 has resulted in new knowledge concerning the pathophysiology of kidney disorders by the identification of a new set of kidney disorders, selective glomerular hypofiltration syndromes. These syndromes, connected to strong increases in mortality and morbidity, are characterized by a selective reduction in the glomerular filtration of 5-30 kDa molecules, such as cystatin C, compared to the filtration of small molecules <1 kDa dominating the glomerular filtrate, for example water, urea and creatinine. At least two types of such disorders, shrunken or elongated pore syndrome, are possible according to the pore model for glomerular filtration. Selective glomerular hypofiltration syndromes are prevalent in investigated populations, and patients with these syndromes often display normal measured GFR or creatinine-based GFR-estimates. The syndromes are characterized by proteomic changes promoting the development of atherosclerosis, indicating antibodies and specific receptor-blocking substances as possible new treatment modalities. Presently, the KDIGO guidelines for diagnosing kidney disorders do not recommend cystatin C as a general marker of kidney function and will therefore not allow the identification of a considerable number of patients with selective glomerular hypofiltration syndromes. Furthermore, as cystatin C is uninfluenced by muscle mass, diet or variations in tubular secretion and cystatin C-based GFR-estimation equations do not require controversial race or sex terms, it is obvious that cystatin C should be a part of future KDIGO guidelines.

Sub-Picosecond Carrier Dynamics Explored using Automated High-Throughput Studies of Doping Inhomogeneity within a Bayesian Framework.

Bottom-up production of semiconductor nanomaterials is often accompanied by inhomogeneity resulting in a spread in electronic properties which may be influenced by the nanoparticle geometry, crystal quality, stoichiometry, or doping. Using photoluminescence spectroscopy of a population of more than 11 000 individual zinc-doped gallium arsenide nanowires, inhomogeneity is revealed in, and correlation between doping and nanowire diameter by use of a Bayesian statistical approach. Recombination of hot-carriers is shown to be responsible for the photoluminescence lineshape; by exploiting lifetime variation across the population, hot-carrier dynamics is revealed at the sub-picosecond timescale showing interband electronic dynamics. High-throughput spectroscopy together with a Bayesian approach are shown to provide unique insight in an inhomogeneous nanomaterial population, and can reveal electronic dynamics otherwise requiring complex pump-probe experiments in highly non-equilibrium conditions.

The chronic stress risk phenotype mirrored in the human retina as a neurodegenerative condition.

The brain is the key organ that orchestrates the stress response which translates to the retina. The retina is an extension of the brain and retinal symptoms in subjects with neurodegenerative diseases substantiated the eye as a window to the brain. The retina is used in this study to determine whether chronic stress reflects neurodegenerative signs indicative of neurodegenerative conditions. A three-year prospective cohort (n = 333; aged 46 ± 9 years) was stratified into stress-phenotype cases (n = 212) and controls (n = 121) by applying the Malan stress-phenotype index. Neurodegenerative risk markers included ischemia (astrocytic S100 calcium-binding protein B/S100B); 24-h blood pressure, proteomics; inflammation (tumor-necrosis-factor-α/TNF-α); neuronal damage (neuron-specific-enolase); anti-apoptosis of retinal-ganglion-cells (beta-nerve-growth-factor), astrocytic activity (glial-fibrillary-acidic-protein); hematocrit (viscosity) and retinal follow-up data [vessels; stress-optic-neuropathy]. Stress-optic-neuropathy risk was calculated from two indices: a newly derived diastolic-ocular-perfusion-pressure cut-point ≥68 mmHg relating to the stress-phenotype; combined with an established cup-to-disk ratio cut-point ≥0.3. Higher stress-optic-neuropathy (39% vs. 17%) and hypertension (73% vs. 16%) prevalence was observed in the stress-phenotype cases vs. controls. Elevated diastolic-ocular-perfusion-pressure, indicating hypoperfusion, was related to arterial narrowing and trend for ischemia increases in the stress-phenotype. Ischemia in the stress-phenotype at baseline, follow-up and three-year changes was related to consistent inflammation (TNF-α and cytokine-interleukin-17-receptor-A), neuron-specific-enolase increases, consistent apoptosis (chitinase-3-like protein 1, low beta-nerve-growth-factor), glial-fibrillary-acidic-protein decreases, elevated viscosity, vein widening as risk marker of endothelial dysfunction in the blood-retinal barrier, lower vein count, and elevated stress-optic-neuropathy. The stress-phenotype and related neurodegenerative signs of ongoing brain ischemia, apoptosis and endothelial dysfunction compromised blood-retinal barrier permeability and optic nerve integrity. In fact, the stress-phenotype could identify persons at high risk of neurodegeneration to indicate a neurodegenerative condition.

Proenkephalin as a biomarker correlates with acute kidney injury: a systematic review with meta-analysis and trial sequential analysis.

BACKGROUND: Proenkephalin A 119-159 (PENK) is freely filtered in the glomerulus with plasma levels correlating with glomerular filtration rate. Therefore, PENK has been proposed as an early indicator of acute kidney injury (AKI) although its performance is dependent on the clinical setting. This meta-analysis aimed to investigate the correlation between PENK levels and the development of AKI. METHODS: We conducted a comprehensive search on the PubMed, Embase, Cochrane databases, the website ClinicalTrials.gov and Cnki.net until June 26, 2023. Summary receiver operating characteristic (SROC) curves were used to amalgamate the overall test performance. Diagnostic odds ratio (DOR) was employed to compare the diagnostic accuracy of PENK with other biomarkers. Quality of the evidence was assessed using the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) criteria. RESULTS: We incorporated 11 observational studies with 3969 patients with an incidence of AKI of 23.4% (929 out of 3969 patients) with the best optimal cutoff value of PENK for early detection of AKI being 57.3 pmol/L. The overall sensitivity and specificity of PENK in identifying AKI were 0.69 (95% CI 0.62-0.75) and 0.76 (95% CI 0.68-0.82), respectively. The combined positive likelihood ratio (LR) stood at 2.83 (95% CI 2.06-3.88), and the negative LR was 0.41 (95% CI 0.33-0.52). The SROC curve showcased pooled diagnostic accuracy of 0.77 (95% CI 0.73-0.81). Interestingly, patients with a history of hypertension or heart failure demonstrated a lower specificity of PENK in correlating the development of AKI. CONCLUSION: Our results indicate that PENK possesses significant potential as a biomarker for the early detection of the development of AKI, using a cutoff point of 57.3 pmol/L for PENK.

Plasma Galectin-4 Levels Are Increased after Stroke in Mice and Humans.

Epidemiological studies have associated plasma galectin-4 (Gal-4) levels with prevalent and incident diabetes, and with an increased risk of coronary artery disease. To date, data regarding possible associations between plasma Gal-4 and stroke are lacking. Using linear and logistic regression analyses, we tested Gal-4 association with prevalent stroke in a population-based cohort. Additionally, in mice fed a high-fat diet (HFD), we investigated whether plasma Gal-4 increases in response to ischemic stroke. Plasma Gal-4 was higher in subjects with prevalent ischemic stroke, and was associated with prevalent ischemic stroke (odds ratio 1.52; 95% confidence interval 1.01-2.30; p = 0.048) adjusted for age, sex, and covariates of cardiometabolic health. Plasma Gal-4 increased after experimental stroke in both controls and HFD-fed mice. HFD exposure was devoid of impact on Gal-4 levels. This study demonstrates higher plasma Gal-4 levels in both experimental stroke and in humans that experienced ischemic stroke.

Prevalence of Subclinical Coronary Artery Atherosclerosis in the General Population.

BACKGROUND: Early detection of coronary atherosclerosis using coronary computed tomography angiography (CCTA), in addition to coronary artery calcification (CAC) scoring, may help inform prevention strategies. We used CCTA to determine the prevalence, severity, and characteristics of coronary atherosclerosis and its association with CAC scores in a general population. METHODS: We recruited 30 154 randomly invited individuals age 50 to 64 years to SCAPIS (the Swedish Cardiopulmonary Bioimage Study). The study includes individuals without known coronary heart disease (ie, no previous myocardial infarctions or cardiac procedures) and with high-quality results from CCTA and CAC imaging performed using dedicated dual-source CT scanners. Noncontrast images were scored for CAC. CCTA images were visually read and scored for coronary atherosclerosis per segment (defined as no atherosclerosis, 1% to 49% stenosis, or ≥50% stenosis). External validity of prevalence estimates was evaluated using inverse probability for participation weighting and Swedish register data. RESULTS: In total, 25 182 individuals without known coronary heart disease were included (50.6% women). Any CCTA-detected atherosclerosis was found in 42.1%; any significant stenosis (≥50%) in 5.2%; left main, proximal left anterior descending artery, or 3-vessel disease in 1.9%; and any noncalcified plaques in 8.3% of this population. Onset of atherosclerosis was delayed on average by 10 years in women. Atherosclerosis was more prevalent in older individuals and predominantly found in the proximal left anterior descending artery. Prevalence of CCTA-detected atherosclerosis increased with increasing CAC scores. Among those with a CAC score >400, all had atherosclerosis and 45.7% had significant stenosis. In those with 0 CAC, 5.5% had atherosclerosis and 0.4% had significant stenosis. In participants with 0 CAC and intermediate 10-year risk of atherosclerotic cardiovascular disease according to the pooled cohort equation, 9.2% had CCTA-verified atherosclerosis. Prevalence estimates had excellent external validity and changed marginally when adjusted to the age-matched Swedish background population. CONCLUSIONS: Using CCTA in a large, random sample of the general population without established disease, we showed that silent coronary atherosclerosis is common in this population. High CAC scores convey a significant probability of substantial stenosis, and 0 CAC does not exclude atherosclerosis, particularly in those at higher baseline risk.

Galectin-4 levels in hospitalized versus non-hospitalized subjects with obesity: the Malmö Preventive Project.

BACKGROUND: Obesity is strongly associated with the development of cardiovascular disease (CVD). However, the heterogenous nature of obesity in CVD-risk is still poorly understood. We aimed to explore novel CVD biomarkers and their possible association with presumed unhealthy obesity, defined as hospitalized subjects with obesity (HO). METHODS: Ninety-two proteins associated with CVD were analyzed in 517 (mean age 67 ± 6 years; 33.7% women) individuals with obesity (BMI ≥30 kg/m2) from the Malmö Preventive Project cohort, using a proximity extension array technique from the Olink CVD III panel. Individuals with at least one recorded hospitalization for somatic disease prior to study baseline were defined as HO phenotypes. Associations between proteins and HO (n = 407) versus non-hospitalized subjects with obesity (NHO, n = 110), were analyzed using multivariable binary logistic regression, adjusted for traditional risk factors. RESULTS: Of 92 analyzed unadjusted associations between biomarkers and HO, increased levels of two proteins were significant at a false discovery rate < 0.05: Galectin-4 (Gal-4) and insulin-like growth factor-binding protein 1 (IGFBP-1). When these two proteins were included in logistic regression analyses adjusted for age and sex, Gal-4 remained significant. Gal-4 was independently associated with the HO phenotype in multivariable logistic regression analysis (OR 1.72; CI95% 1.16-2.54). Post-hoc analysis revealed that this association was only present in the subpopulation with diabetes (OR 2.26; CI95% 1.25-4.07). However, an interaction analysis was performed, showing no significant interaction between Gal-4 and prevalent diabetes (p = 0.16). CONCLUSIONS: In middle-aged and older individuals with obesity, increased Gal-4 levels were associated with a higher probability of HO. This association was only significant in subjects with diabetes only, further implying a role for Gal-4 in diabetes and its complications.

Alterations to Cerebral Perfusion, Metabolite Profiles, and Neuronal Morphology in the Hippocampus and Cortex of Male and Female Mice during Chronic Exposure to a High-Salt Diet.

Excess dietary salt reduces resting cerebral blood flow (CBF) and vascular reactivity, which can limit the fueling of neuronal metabolism. It is hitherto unknown whether metabolic derangements induced by high-salt-diet (HSD) exposure during adulthood are reversed by reducing salt intake. In this study, male and female mice were fed an HSD from 9 to 16 months of age, followed by a normal-salt diet (ND) thereafter until 23 months of age. Controls were continuously fed either ND or HSD. CBF and metabolite profiles were determined longitudinally by arterial spin labeling magnetic resonance imaging and magnetic resonance spectroscopy, respectively. HSD reduced cortical and hippocampal CBF, which recovered after dietary salt normalization, and affected hippocampal but not cortical metabolite profiles. Compared to ND, HSD increased hippocampal glutamine and phosphocreatine levels and decreased creatine and choline levels. Dietary reversal only allowed recovery of glutamine levels. Histology analyses revealed that HSD reduced the dendritic arborization and spine density of cortical and hippocampal neurons, which were not recovered after dietary salt normalization. We conclude that sustained HSD exposure throughout adulthood causes permanent structural and metabolic alterations to the mouse brain that are not fully normalized by lowering dietary salt during aging.

Aerotaxy: gas-phase epitaxy of quasi 1D nanostructures.

Cost- and resource-efficient growth is necessary for many applications of semiconductor nanowires. We here present the design, operational details and theory behind Aerotaxy, a scalable alternative technology for producing quality crystalline nanowires at a remarkably high growth rate and throughput. Using size-controlled Au seed particles and organometallic precursors, Aerotaxy can produce nanowires with perfect crystallinity and controllable dimensions, and the method is suitable to meet industrial production requirements. In this report, we explain why Aerotaxy is an efficient method for fabricating semiconductor nanowires and explain the technical aspects of our custom-built Aerotaxy system. Investigations using SEM (scanning electron microscope), TEM (transmission electron microscope) and other characterization methods are used to support the claim that Aerotaxy is indeed a scalable method capable of producing nanowires with reproducible properties. We have investigated both binary and ternary III-V semiconductor material systems like GaAs and GaAsP. In addition, common aspects of Aerotaxy nanowires deduced from experimental observations are used to validate the Aerotaxy growth model, based on a computational flow dynamics (CFD) approach. We compare the experimental results with the model behaviour to better understand Aerotaxy growth.

Glucose-dependent insulinotropic peptide and risk of cardiovascular events and mortality: a prospective study.

AIMS/HYPOTHESIS: Evidence that glucose-dependent insulinotropic peptide (GIP) and/or the GIP receptor (GIPR) are involved in cardiovascular biology is emerging. We hypothesised that GIP has untoward effects on cardiovascular biology, in contrast to glucagon-like peptide 1 (GLP-1), and therefore investigated the effects of GIP and GLP-1 concentrations on cardiovascular disease (CVD) and mortality risk. METHODS: GIP concentrations were successfully measured during OGTTs in two independent populations (Malmö Diet Cancer-Cardiovascular Cohort [MDC-CC] and Prevalence, Prediction and Prevention of Diabetes in Botnia [PPP-Botnia]) in a total of 8044 subjects. GLP-1 (n = 3625) was measured in MDC-CC. The incidence of CVD and mortality was assessed via national/regional registers or questionnaires. Further, a two-sample Mendelian randomisation (2SMR) analysis between the GIP pathway and outcomes (coronary artery disease [CAD] and myocardial infarction) was carried out using a GIP-associated genetic variant, rs1800437, as instrumental variable. An additional reverse 2SMR was performed with CAD as exposure variable and GIP as outcome variable, with the instrumental variables constructed from 114 known genetic risk variants for CAD. RESULTS: In meta-analyses, higher fasting levels of GIP were associated with risk of higher total mortality (HR[95% CI] = 1.22 [1.11, 1.35]; p = 4.5 × 10-5) and death from CVD (HR[95% CI] 1.30 [1.11, 1.52]; p = 0.001). In accordance, 2SMR analysis revealed that increasing GIP concentrations were associated with CAD and myocardial infarction, and an additional reverse 2SMR revealed no significant effect of CAD on GIP levels, thus confirming a possible effect solely of GIP on CAD. CONCLUSIONS/INTERPRETATION: In two prospective, community-based studies, elevated levels of GIP were associated with greater risk of all-cause and cardiovascular mortality within 5-9 years of follow-up, whereas GLP-1 levels were not associated with excess risk. Further studies are warranted to determine the cardiovascular effects of GIP per se.

Metabolically Healthy Obesity (MHO)-New Research Directions for Personalised Medicine in Cardiovascular Prevention.

PURPOSE OF REVIEW: To discuss new findings on the heterogeneity of obesity and associated risks. RECENT FINDINGS: Obesity is a public health problem of immense importance on a global scale. However, epidemiological findings and clinical studies have revealed that obesity is a heterogeneous phenotype and that not all obese subjects run the same risk for complications. Current research has tried to describe so-called metabolically healthy obesity (MHO), defined by lack of risk factors included in the metabolic syndrome. These subjects will not escape long-term complications, but mortality risk is not increased. However, a new definition of MHO has recently been proposed, based on the lack of hospitalisation for somatic disease for decades in middle life. MHO subjects defined in this way are characterised by being "fat and fit" and also run a lower risk of long-term complications. If MHO could be better understood, this could contribute to a more diverse clinical approach to obesity based on personalised medicine.

Optical far-field extinction of a single GaAs nanowire towards in situ size control of aerotaxy nanowire growth.

A substrate-free approach of semiconductor nanowire growth has been achieved by the aerotaxy technique previously. In this work, we propose an in situ method to monitor the size of nanowires through non-destructive optical-extinction measurements. Our work aims to build a theoretical look-up database of extinction spectra for a single nanowire of varying dimensions. We describe the origin of possible peaks in the spectra, for example due to nanowire-length dependent Fabry-Perot resonances and nanowire-diameter dependent TM and TE mode resonances. Furthermore, we show that the Au catalyst on top of the nanowire can be ignored in the simulations when the volume of the nanowire is an order of magnitude larger than that of the Au catalyst and the diameter is small compared to the incident wavelength. For the calculation of the extinction spectra, we use the finite element method, the discrete dipole approximation and the Mie theory. To compare with experimental measurements of randomly oriented nanowires, we perform an averaging over nanowire orientation for the modeled results. However, in the experiments, nanowires are accumulating on the quartz window of the measurement setup, which leads to increasing uncertainty in the comparison with the experimental extinction spectra. This uncertainty can be eliminated by considering both a sparse and a dense collection of nanowires on the quartz window in the optical simulations. Finally, we create a database of extinction spectra for a GaAs nanowire of varying diameters and lengths. This database can be used to estimate the diameter and the length of the nanowires by comparing the position of a peak and the peak-to-shoulder difference in the extinction spectrum. Possible tapering of nanowires can be monitored through the appearance of an additional peak at a wavelength of 700-800 nm.

Calibrating Range Measurements of Lidars Using Fixed Landmarks in Unknown Positions.

We consider the problem of calibrating range measurements of a Light Detection and Ranging (lidar) sensor that is dealing with the sensor nonlinearity and heteroskedastic, range-dependent, measurement error. We solved the calibration problem without using additional hardware, but rather exploiting assumptions on the environment surrounding the sensor during the calibration procedure. More specifically we consider the assumption of calibrating the sensor by placing it in an environment so that its measurements lie in a 2D plane that is parallel to the ground. Then, its measurements come from fixed objects that develop orthogonally w.r.t. the ground, so that they may be considered as fixed points in an inertial reference frame. Moreover, we consider the intuition that moving the distance sensor within this environment implies that its measurements should be such that the relative distances and angles among the fixed points above remain the same. We thus exploit this intuition to cast the sensor calibration problem as making its measurements comply with this assumption that "fixed features shall have fixed relative distances and angles". The resulting calibration procedure does thus not need to use additional (typically expensive) equipment, nor deploy special hardware. As for the proposed estimation strategies, from a mathematical perspective we consider models that lead to analytically solvable equations, so to enable deployment in embedded systems. Besides proposing the estimators we moreover analyze their statistical performance both in simulation and with field tests. We report the dependency of the MSE performance of the calibration procedure as a function of the sensor noise levels, and observe that in field tests the approach can lead to a tenfold improvement in the accuracy of the raw measurements.

BDNF increases associated with constant troponin T levels and may protect against poor cognitive interference control: The SABPA prospective study.

BACKGROUND: Brain-derived neurotrophic factor (BDNF) modulates brain health and cognition, which can interfere with executive cognitive function. BDNF was implicated with microcirculatory ischaemia and may reflect cardiomyocyte injury. We aimed to determine whether prospective changes (%Δ) in BDNF and cardiac troponin T (cTnT) will be associated with executive cognitive function in a bi-ethnic cohort. DESIGN: A prospective investigation was conducted over a three-year period in a bi-ethnic sex cohort (N = 338; aged 20-65 years) from South Africa. Fasting serum samples for BDNF and cTnT were obtained. The STROOP-color-word conflict test (CWT) was applied to assess executive cognitive function at baseline. RESULTS: In Blacks, BDNF (P < 0.001) increased over the three-year period while cTnT did not change. In contrast, in Whites, BDNF and cTnT decreased over three years. In Black men, no change in cTnT was associated with increased ΔBDNF (ß = 0.25; 95% CI 0.05-0.45; P = 0.02). In the Black men, constant cTnT levels were inversely associated with executive cognitive function (ß = -0.33; 95% CI -0.53 to -0.12; P = 0.003). Three-year increases in BDNF increased the likelihood for chronic lower cTnT levels at a pre-established cut-point of <4.2 ng/L [OR = 2.35 (1.12-4.94), P = 0.02]. The above associations were not found in the White sex groups. CONCLUSIONS: Central neural control mechanisms may have upregulated BDNF in Black men as a way to protect against myocardial stress progression and to possibly improve processes related to cognitive interference control. High-sensitive cTnT levels may act as an early predictor of disturbed neural control mechanisms.

Electron Tomography Reveals the Droplet Covered Surface Structure of Nanowires Grown by Aerotaxy.

For the purpose of functionalizing III-V semiconductor nanowires using n-doping, Sn-doped GaAs zincblende nanowires are produced, using the growth method of Aerotaxy. The growth conditions used are such that Ga droplets, formed on the nanowire surface, increase in number and concentrations when the Sn-precursor concentration is increased. Droplet-covered wires grown with varying Sn concentrations are analyzed by transmission electron microscopy and electron tomography, which together establish the positioning of the droplets to be preferentially on {-111}B facets. These facets have the same polarity as the main wire growth direction, [-1-1-1]B. This means that the generated Ga particles can form nucleation sites for possible nanowire branch growth. The concept of azimuthal mapping is introduced as a useful tool for nanowire surface visualization and evaluation. It is demonstrated here that electron tomography is useful in revealing both the surface and internal morphologies of the nanowires, opening up for applications in the analysis of more structurally complicated systems like radially asymmetrical nanowires. The analysis also gives a further understanding of the limits of the dopants which can be used for Aerotaxy nanowires.

n-type doping and morphology of GaAs nanowires in Aerotaxy.

Controlled doping in semiconductor nanowires modifies their electrical and optical properties, which are important for high efficiency optoelectronic devices. We have grown n-type (Sn) doped GaAs nanowires in Aerotaxy, a new continuous gas phase mass production technique. The morphology of Sn doped nanowires is found to be a strong function of dopant, tetraethyltin to trimethylgallium flow ratio, Au-Ga-Sn alloying, and nanowire growth temperatures. High temperature and high flow ratios result in low morphological quality nanowires and in parasitic growth on the wire base and surface. Alloying and growth temperatures of 400 °C and 530 °C, respectively, resulted in good morphological quality nanowires for a flow ratio of TESn to TMGa up to 2.25 × 10-3. The wires are pure zinc-blende for all investigated growth conditions, whereas nanowires grown by metal-organic vapor phase epitaxy with the same growth conditions are usually mainly Wurtzite. The growth rate of the doped wires is found to be dependent more on the TESn flow fraction than on alloying and nanowire growth temperatures. Our photoluminescence measurements, supported by four-point probe resistivity measurements, reveal that the carrier concentration in the doped wires varies only slightly (1-3) × 1019 cm-3 with TESn flow fraction and both alloying and growth temperatures, indicating that good morphological quality wires with high carrier density can be grown with low TESn flow. Carrier concentrations lower than 1019 cm-3 can be grown by further reducing the flow fraction of TESn, which may give better morphology wires.