Multi-omics for studying and understanding polar life.

Polar ecosystems are experiencing amongst the most rapid rates of regional warming on Earth. Here, we discuss 'omics' approaches to investigate polar biodiversity, including the current state of the art, future perspectives and recommendations. We propose a community road map to generate and more fully exploit multi-omics data from polar organisms. These data are needed for the comprehensive evaluation of polar biodiversity and to reveal how life evolved and adapted to permanently cold environments with extreme seasonality. We argue that concerted action is required to mitigate the impact of warming on polar ecosystems via conservation efforts, to sustainably manage these unique habitats and their ecosystem services, and for the sustainable bioprospecting of novel genes and compounds for societal gain.

Molecular responses to ocean acidification in an Antarctic bivalve and an ascidian.

Southern Ocean organisms are considered particularly vulnerable to Ocean acidification (OA), as they inhabit cold waters where calcite-aragonite saturation states are naturally low. It is also generally assumed that OA would affect calcifying animals more than non-calcifying animals. In this context, we aimed to study the impact of reduced pH on both types of species: the ascidian Cnemidocarpa verrucosa sp. A, and the bivalve Aequiyoldia eightsii, from an Antarctic fjord. We used gene expression profiling and enzyme activity to study the responses of these two Antarctic benthic species to OA. We report the results of an experiment lasting 66 days, comparing the molecular mechanisms underlying responses under two pCO2 treatments (ambient and elevated pCO2). We observed 224 up-regulated and 111 down-regulated genes (FC ≥ 2; p-value ≤ 0.05) in the ascidian. In particular, the decrease in pH caused an upregulation of genes involved in the immune system and antioxidant response. While fewer differentially expressed (DE) genes were observed in the infaunal bivalve, 34 genes were up-regulated, and 69 genes were downregulated (FC ≥ 2; p-value ≤ 0.05) in response to OA. We found downregulated genes involved in the oxidoreductase pathway (such as glucose dehydrogenase and trimethyl lysine dioxygenase), while the heat shock protein 70 was up-regulated. This work addresses the effect of OA in two common, widely distributed Antarctic species, showing striking results. Our major finding highlights the impact of OA on the non-calcifying species, a result that differ from the general trend, which describes a higher impact on calcifying species. This calls for discussion of potential effects on non-calcifying species, such as ascidians, a diverse and abundant group that form extended three-dimensional clusters in shallow waters and shelf areas in the Southern Ocean.

Societal importance of Antarctic negative feedbacks on climate change: blue carbon gains from sea ice, ice shelf and glacier losses.

Diminishing prospects for environmental preservation under climate change are intensifying efforts to boost capture, storage and sequestration (long-term burial) of carbon. However, as Earth's biological carbon sinks also shrink, remediation has become a key part of the narrative for terrestrial ecosystems. In contrast, blue carbon on polar continental shelves have stronger pathways to sequestration and have increased with climate-forced marine ice losses-becoming the largest known natural negative feedback on climate change. Here we explore the size and complex dynamics of blue carbon gains with spatiotemporal changes in sea ice (60-100 MtCyear-1), ice shelves (4-40 MtCyear-1 = giant iceberg generation) and glacier retreat (< 1 MtCyear-1). Estimates suggest that, amongst these, reduced duration of seasonal sea ice is most important. Decreasing sea ice extent drives longer (not necessarily larger biomass) smaller cell-sized phytoplankton blooms, increasing growth of many primary consumers and benthic carbon storage-where sequestration chances are maximal. However, sea ice losses also create positive feedbacks in shallow waters through increased iceberg movement and scouring of benthos. Unlike loss of sea ice, which enhances existing sinks, ice shelf losses generate brand new carbon sinks both where giant icebergs were, and in their wake. These also generate small positive feedbacks from scouring, minimised by repeat scouring at biodiversity hotspots. Blue carbon change from glacier retreat has been least well quantified, and although emerging fjords are small areas, they have high storage-sequestration conversion efficiencies, whilst blue carbon in polar waters faces many diverse and complex stressors. The identity of these are known (e.g. fishing, warming, ocean acidification, non-indigenous species and plastic pollution) but not their magnitude of impact. In order to mediate multiple stressors, research should focus on wider verification of blue carbon gains, projecting future change, and the broader environmental and economic benefits to safeguard blue carbon ecosystems through law.

Molecular mechanisms underlying responses of the Antarctic coral Malacobelemnon daytoni to ocean acidification.

Benthic organisms of the Southern Ocean are particularly vulnerable to ocean acidification (OA), as they inhabit cold waters where calcite-aragonite saturation states are naturally low. OA most strongly affects animals with calcium carbonate skeletons or shells, such as corals and mollusks. We exposed the abundant cold-water coral Malacobelemnon daytoni from an Antarctic fjord to low pH seawater (LpH) (7.68 ± 0.17) to test its physiological responses to OA, at the level of gene expression (RT-PCR) and enzyme activity. Corals were exposed in short- (3 days) and long-term (54 days) experiments to two pCO2 conditions (ambient and elevated pCO2 equaling RCP 8.5, IPCC 2019, approximately 372.53 and 956.78 µatm, respectively). Of the eleven genes studied through RT-PCR, six were significantly upregulated compared with control in the short-term in the LpH condition, including the antioxidant enzyme superoxide dismutase (SOD), Heat Shock Protein 70 (HSP70), Toll-like receptor (TLR), galaxin and ferritin. After long-term exposure to low pH conditions, RT-PCR analysis showed seven genes were upregulated. These include the mannose-binding C-Lectin and HSP90. Also, the expression of TLR and galaxin, among others, continued to be upregulated after long-term exposure to LpH. Expression of carbonic anhydrase (CA), a key enzyme involved in calcification, was also significantly upregulated after long-term exposure. Our results indicated that, after two months, M. daytoni is not acclimatized to this experimental LpH condition. Gene expression profiles revealed molecular impacts that were not evident at the enzyme activity level. Consequently, understanding the molecular mechanisms behind the physiological processes in the response of a coral to LpH is critical to understanding the ability of polar species to cope with future environmental changes. Approaches integrating molecular tools into Antarctic ecological and/or conservation research make an essential contribution given the current ongoing OA processes.

Excessive daytime sleepiness, morning tiredness and major adverse cardiovascular events in patients with chronic coronary syndrome.

BACKGROUND: Sleep-related breathing disorders (SRBDs), particularly obstructive sleep apnoea, are associated with increased cardiovascular (CV) risk. However, it is not known whether individual questions used for SRBD screening are associated with major adverse CV events (MACE) and death specifically in patients with chronic coronary syndrome (CCS). METHODS: Symptoms associated with SRBD were assessed by a baseline questionnaire in 15,640 patients with CCS on optimal secondary preventive therapy in the STABILITY trial. The patients reported the frequency (never/rarely, sometimes, often and always) of: 1) loud snoring; 2) more than one awakening/night; 3) morning tiredness (MT); 4) excessive daytime sleepiness (EDS); or 5) gasping, choking or apnoea when asleep. In adjusted Cox regression models, associations between the frequency of SRBD symptoms and CV outcomes were assessed with never/rarely as reference. RESULTS: During a median follow-up time of 3.7 years, 1,588 MACE events (541 CV deaths, 749 nonfatal myocardial infarctions [MI] and 298 nonfatal strokes) occurred. EDS was associated (hazard ratio [HR], 95% confidence interval [CI]) with increased risk of MACE (sometimes 1.14 [1.01-1.29], often 1.19 [1.01-1.40] and always 1.43 [1.15-1.78]), MI (always 1.61 [1.17-2.20]) and all-cause death (often 1.26 [1.05-1.52] and always 1.71 [1.35-2.15]). MT was associated with higher risk of MACE (often 1.23 [1.04-1.45] and always 1.46 [1.18-1.81]), MI (always 1.61 [1.22-2.14]) and all-cause death (always 1.54 [1.20-1.98]). The other SRBD-related questions were not consistently associated with worse outcomes. CONCLUSIONS: In patients with CCS, gradually higher levels of EDS and MT were independently associated with increased risk of MACE, including mortality.

Organization of intensive cardiac care units in Europe: Results of a multinational survey.

BACKGROUND: The present survey aims to describe the intensive cardiac care unit organization and admission policies in Europe. METHODS: A total of 228 hospitals (61% academic) from 27 countries participated in this survey. In addition to the organizational aspects of the intensive cardiac care units, including classification of the intensive cardiac care unit levels, data on the admission diagnoses were gathered from consecutive patients who were admitted during a two-day period. Admission policies were evaluated by comparing illness severity with the intensive cardiac care unit level. Gross national income was used to differentiate high-income countries (n=13) from middle-income countries (n=14). RESULTS: A total of 98% of the hospitals had an intensive cardiac care unit: 70% had a level 1 intensive cardiac care unit, 76% had a level 2 intensive cardiac care unit, 51% had a level 3 intensive cardiac care unit, and 60% of the hospitals had more than one intensive cardiac care unit level. High-income countries tended to have more level 3 intensive cardiac care units than middle-income countries (55% versus 41%, p=0.07). A total of 5159 admissions were scored on illness severity: 63% were low severity, 24% were intermediate severity, and 12% were high severity. Patients with low illness severity were predominantly admitted to level 1 intensive cardiac care units, whereas patients with high illness severity were predominantly admitted to level 2 and 3 intensive cardiac care units. A policy mismatch was observed in 12% of the patients; some patients with high illness severity were admitted to level 1 intensive cardiac care units, which occurred more often in middle-income countries, whereas some patients with low illness severity were admitted to level 3 intensive cardiac care units, which occurred more frequently in high-income countries. CONCLUSION: More than one-third of the admitted patients were considered intermediate or high risk. Although patients with higher illness severity were mostly admitted to high-level intensive cardiac care units, an admission policy mismatch was observed in 12% of the patients; this mismatch was partly related to insufficient logistic intensive cardiac care unit capacity.

Co-solvent effects on reaction rate and reaction equilibrium of an enzymatic peptide hydrolysis.

This work presents an approach that expresses the Michaelis constant KaM and the equilibrium constant Kth of an enzymatic peptide hydrolysis based on thermodynamic activities instead of concentrations. This provides KaM and Kth values that are independent of any co-solvent. To this end, the hydrolysis reaction of N-succinyl-l-phenylalanine-p-nitroanilide catalysed by the enzyme α-chymotrypsin was studied in pure buffer and in the presence of the co-solvents dimethyl sulfoxide, trimethylamine-N-oxide, urea, and two salts. A strong influence of the co-solvents on the measured Michaelis constant (KM) and equilibrium constant (Kx) was observed, which was found to be caused by molecular interactions expressed as activity coefficients. Substrate and product activity coefficients were used to calculate the activity-based values KaM and Kth for the co-solvent free reaction. Based on these constants, the co-solvent effect on KM and Kx was predicted in almost quantitative agreement with the experimental data. The approach presented here does not only reveal the importance of understanding the thermodynamic non-ideality of reactions taking place in biological solutions and in many technological applications, it also provides a framework for interpreting and quantifying the multifaceted co-solvent effects on enzyme-catalysed reactions that are known and have been observed experimentally for a long time.

Psychosocial stress and major cardiovascular events in patients with stable coronary heart disease.

OBJECTIVES: Assess the risk of ischaemic events associated with psychosocial stress in patients with stable coronary heart disease (CHD). METHODS: Psychosocial stress was assessed by a questionnaire in 14 577 patients (median age 65.0, IQR 59, 71; 81.6% males) with stable CHD on optimal secondary preventive therapy in the prospective randomized STABILITY clinical trial. Adjusted Cox regression models were used to assess associations between individual stressors, baseline cardiovascular risk factors and outcomes. RESULTS: After 3.7 years of follow-up, depressive symptoms, loss of interest and financial stress were associated with increased risk (hazard ratio, 95% confidence interval) of CV death (1.21, 1.09-1.34; 1.15, 1.05-1.27; and 1.19, 1.08-1.30, respectively) and the primary composite end-point of CV death, nonfatal MI or nonfatal stroke (1.21, 1.13-1.30; 1.19, 1.11-1.27; and 1.17, 1.10-1.24, respectively). Living alone was related to higher risk of CV death (1.68, 1.38-2.05) and the primary composite end-point (1.28, 1.11-1.48), whereas being married as compared with being widowed, was associated with lower risk of CV death (0.64, 0.49-0.82) and the primary composite end-point (0.81, 0.67-0.97). CONCLUSIONS: Psychosocial stress, such as depressive symptoms, loss of interest, living alone and financial stress, were associated with increased CV mortality in patients with stable CHD despite optimal medical secondary prevention treatment. Secondary prevention of CHD should therefore focus also on psychosocial issues both in clinical management and in future clinical trials.

Emotional distress as a predictor of statin non-adherence among Swedish first-time myocardial infarction patients, 2006-2013.

BACKGROUND: Emotional distress (depression and anxiety) has been known to affect mortality after a myocardial infarction (MI). One possible mechanism is through medication non-adherence. Few studies have investigated the link between statin adherence and emotional distress, and results are not consistent. We aimed to explore whether emotional distress affects adherence among first-time MI patients younger than 75years old receiving a prescription for the first time. METHODS: We identified first-MI individuals younger than 75years from the SWEDEHEART national quality registers discharged with a statin prescription. The main exposure was the anxiety/depression portion of the EQ-5D from Interview 1 (6-10weeks post-MI) and Interview 2 (12-14months post-MI). We calculated adherence from the Swedish Prescribed Drugs Register during three observation periods (OP): [1] Interview 1 to Interview 2, [2] one year post Interview 2, and [3] two years post Interview 1. RESULTS: Emotional distress at Interview 1 was not associated with statin adherence for OP1 (RR: 0.99, 95% CI: 0.98, 1.01). Emotional distress at Interview 2 was associated with lower adherence one year later (RR: 0.95, 95% CI: 0.93, 0.98). Emotional distress at Interview 1 was associated with a small decrease in adherence in the complete OP for adherence (RR: 0.98, 95% CI: 0.96, 0.99). CONCLUSION: Emotional distress was marginally, but independently, associated with lower adherence to statin two years after the MI. Our study suggests that emotional distress may be an important factor for long-term statin adherence, and, thus, may play a clinically important role in long-term outcome.

Pelagic and benthic communities of the Antarctic ecosystem of Potter Cove: Genomics and ecological implications.

Molecular technologies are more frequently applied in Antarctic ecosystem research and the growing amount of sequence-based information available in databases adds a new dimension to understanding the response of Antarctic organisms and communities to environmental change. We apply molecular techniques, including fingerprinting, and amplicon and metagenome sequencing, to understand biodiversity and phylogeography to resolve adaptive processes in an Antarctic coastal ecosystem from microbial to macrobenthic organisms and communities. Interpretation of the molecular data is not only achieved by their combination with classical methods (pigment analyses or microscopy), but furthermore by combining molecular with environmental data (e.g., sediment characteristics, biogeochemistry or oceanography) in space and over time. The studies form part of a long-term ecosystem investigation in Potter Cove on King-George Island, Antarctica, in which we follow the effects of rapid retreat of the local glacier on the cove ecosystem. We formulate and encourage new approaches to integrate molecular tools into Antarctic ecosystem research, environmental conservation actions, and polar ocean observatories.

Novel approaches in primary cardiovascular disease prevention: the HOPE-3 trial rationale, design, and participants' baseline characteristics

AbstractBACKGROUND:Cholesterol and blood pressure (BP) can be effectively and safely lowered with statin drugs and BP-lowering drugs, reducing major cardiovascular (CV) events by 20%-30% within 5 years in high-risk individuals. However, there are limited data in lower-risk populations. The Heart Outcomes Prevention Evaluation-3 (HOPE-3) trial is evaluating whether cholesterol lowering with a statin drug, BP lowering with low doses of 2 antihypertensive agents, and their combination safely reduce major CV events in individuals at intermediate risk who have had no previous vascular events and have average cholesterol and BP levels.METHODS:A total of 12,705 women 65 years or older and men 55 years or older with at least 1 CV risk factor, no known CV disease, and without any clear indication or contraindication to the study drugs were randomized to rosuvastatin 10 mg/d or placebo and to candesartan/hydrochlorothiazide 16/12.5 mg/d or placebo (2 × 2 factorial design) and will be followed for a mean of 5.8 years. The coprimary study outcomes are the composite of CV death, nonfatal myocardial infarction (MI), and nonfatal stroke and the composite of CV death, nonfatal MI, nonfatal stroke, resuscitated cardiac arrest, heart failure, and arterial revascularization.RESULTS:Participants were recruited from 21 countries in North America, South America, Europe, Asia, and Australia. Mean age at randomization was 66 years and 46% were women.CONCLUSIONS:The HOPE-3 trial will provide new information on cholesterol and BP lowering in intermediate-risk populations with average cholesterol and BP levels and is expected to inform approaches to primary prevention worldwide (HOPE-3 ClinicalTrials.govNCT00468923).

Oat1/3 restoration protects against renal damage after ischemic AKI.

Expression of proximal tubular organic anion transporters Oat1 and Oat3 is reduced by PGE2 after renal ischemia and reperfusion (I/R) injury. We hypothesized that impaired expression of Oat1/3 is decisively involved in the deterioration of renal function after I/R injury. Therefore, we administered probenecid, which blocks proximal tubular indomethacin uptake, to abolish the indomethacin-mediated restoration of Oat1/3 regulation and its effect on renal functional and morphological outcome. Ischemic acute kidney injury (iAKI) was induced in rats by bilateral clamping of renal arteries for 45 min with 24-h follow-up. Low-dose indomethacin (1 mg/kg) was given intraperitoneally (ip) at the end of ischemia. Probenecid (50 mg/kg) was administered ip 20 min later. Indomethacin restored the expression of Oat1/3, PAH net secretion, and PGE2 clearance. Additionally, indomethacin improved kidney function as measured by glomerular filtration rate (GFR), renal perfusion as determined by corrected PAH clearance, and morphology, whereas it reduced renal cortical apoptosis and nitric oxide production. Notably, indomethacin did not affect inflammation parameters in the kidneys (e.g., monocyte chemoattractant protein-1, ED1+ cells). On the other hand, probenecid blocked the indomethacin-induced restoration of Oat1/3 and moreover abrogated all beneficial effects. Our study indicates that the beneficial effect of low-dose indomethacin in iAKI is not due to its anti-inflammatory potency, but in contrast to its restoration of Oat1/3 expression and/or general renal function. Inhibition of proximal tubular indomethacin uptake abrogates the beneficial effect of indomethacin by resetting the PGE2-mediated Oat1/3 impairment, thus reestablishing renal damage. This provides evidence for a mechanistic effect of Oat1/3 in a new model of the induction of renal damage after iAKI.

Review of free software tools for image analysis of fluorescence cell micrographs.

An increasing number of free software tools have been made available for the evaluation of fluorescence cell micrographs. The main users are biologists and related life scientists with no or little knowledge of image processing. In this review, we give an overview of available tools and guidelines about which tools the users should use to segment fluorescence micrographs. We selected 15 free tools and divided them into stand-alone, Matlab-based, ImageJ-based, free demo versions of commercial tools and data sharing tools. The review consists of two parts: First, we developed a criteria catalogue and rated the tools regarding structural requirements, functionality (flexibility, segmentation and image processing filters) and usability (documentation, data management, usability and visualization). Second, we performed an image processing case study with four representative fluorescence micrograph segmentation tasks with figure-ground and cell separation. The tools display a wide range of functionality and usability. In the image processing case study, we were able to perform figure-ground separation in all micrographs using mainly thresholding. Cell separation was not possible with most of the tools, because cell separation methods are provided only by a subset of the tools and are difficult to parametrize and to use. Most important is that the usability matches the functionality of a tool. To be usable, specialized tools with less functionality need to fulfill less usability criteria, whereas multipurpose tools need a well-structured menu and intuitive graphical user interface.

Randomized, double-blind phase II study to compare nitroglycerin plus oral vinorelbine plus cisplatin with oral vinorelbine plus cisplatin alone in patients with stage IIIB/IV non-small cell lung cancer (NSCLC).

OBJECTIVES: Adding nitroglycerin to the combination of vinorelbine plus cisplatin has been reported to improve the overall survival (OS) of Asian patients with stage IIIB/IV non-small cell lung cancer (NSCLC) probably due to better drug delivery based on changed vascular tonus. The main objective of our study was to evaluate the effect of adding nitroglycerin to vinorelbine and cisplatin in a Caucasian population. METHODS: 66 chemonaïve patients with stage IIIB/IV NSCLC received oral vinorelbine (first cycle 60 mg/m(2), subsequent cycles: 80 mg/m(2) in the absence of any hematological toxicity ≥ grade 3 in cycle 1) once daily on days 1 and 8 of each cycle and cisplatin (80 mg/m(2) i.v.) on day 1 of each cycle (q3w). Nitroglycerin (arm A, n=34) or placebo patches (arm B, n=32) were administered once daily from day -3 to day 2 of each cycle and were removed about 12h after administration. One nitroglycerin patch contained 25mg nitroglycerin. RESULTS: Median age was 62.5 (33-82) years. In the overall population (n=66), the objective response rate (ORR) was 27.3% (all PR; 95%CI: 17.0-39.6), with a disease control rate (DCR) of 57.6% (95%CI: 44.8-69.7), a median time to progression (TTP) of 4.8 months (n=58; 95%CI: 3.4-5.9) and a median overall survival (OS) of 11.5 months (95%CI: 7.9-13.6). ORR and DCR were numerically higher in arm A than in arm B (35.3% vs. 18.8% and 61.8% vs. 53.1%, respectively), whereas TTP and OS were comparable. The main hematological and non-hematological toxicities grade ≥ 3 were moderate with no significant differences between the two treatment arms. CONCLUSIONS: Overall, oral vinorelbine plus cisplatin showed a high level of efficacy and adequate tolerability in first line treatment of NSCLC. Despite the low sample size per group the results seem to confirm the previous results reported in Asian patients.

Single trial P300 detection in children using expert knowledge and SOM.

Preliminary results of an automatic system for single trial P300 visual evoked potential events detection are presented. For each single trial P300, several candidate events were generated, and then filtered, using 3 wave features. The surviving candidate events were fed into a SOM-based classifier. A context filter was applied before the final output. No stationary condition of the P300 is involved in the algorithms. Recordings of 27 assessment sessions, each with 120 trials, were visually inspected by experts to identify and mark the P300 events, which was accomplished in about one third of the trials. The dataset was divided in training (18) and testing (9) subsets. The system identifies the initial and end times of the P300; it obtained a sensitivity of 53.9%, a specificity of 64.0% and an accuracy of 61.2% in the testing dataset.

A balanced sleep/wakefulness classification method based on actigraphic data in adolescents.

Several research groups have developed automated sleep-wakefulness classifiers for night wrist actigraphic (ACT) data. These classifiers tend to be unbalanced, with a tendency to overestimate the detection of sleep, at the expense of poorer detection of wakefulness. The reason for this is that the measure of success in previous works was the maximization of the overall accuracy, disregarding the balance between sensitivity and specificity. The databases were usually sleep recordings, hence the over-representation of sleep samples. In this work an Artificial Neural Network (ANN), sleep-wakefulness classifier is presented. ACT data was collected every minute. An 11-min moving window was used as observing frame for data analysis, as applied in previous sleep ACT studies. However, our feature set adds new variables such as the time of the day, the median and the median absolute deviation. Sleep and Wakefulness data were balanced to improve the system training. A comparison with previous studies can still be done, by choosing the point in the ROC curve associated with the corresponding data balance. Our results are compared with a polysomnogram-based hypnogram as golden standard, rendering an accuracy of 92.8%, a sensitivity of 97.6% and a specificity of 73.4%. Geometric mean between sensitivity and specificity is 84.9%.

Night time sleep macrostructure is altered in otherwise healthy 10-year-old overweight children.

OBJECTIVE: Epidemiological evidence shows an inverse relationship between sleep duration and overweight/obesity risk. However, there are few polysomnographic studies that relate the organization of sleep stages to pediatric overweight (OW). We compared sleep organization in otherwise healthy OW and normal-weight (NW) 10-year-old children. SUBJECTS: Polysomnographic assessments were performed in 37 NW and 59 OW children drawn from a longitudinal study beginning in infancy. Weight and height were used to evaluate body mass index (BMI) according to international criteria. Non-rapid eye movement (NREM) sleep (stages N1, N2 and N3), rapid eye movement (REM) sleep (stage R) and wakefulness (stage W) were visually scored. Sleep parameters were compared in NW and OW groups for the whole sleep period time (SPT) and for each successive third of it using independent Student's t-tests or nonparametric tests. The relationship between BMI and sleep variables was evaluated by correlation analyses controlling for relevant covariates. RESULTS: The groups were similar in timing of sleep onset and offset, and sleep period time. BMI was inversely related to total sleep time (TST) and sleep efficiency. OW children showed reduced TST, sleep efficiency and stage R amount, but higher stage W amount. In analysis by thirds of the SPT, the duration of stage N3 episodes was shorter in the first third and longer in the second third in OW children as compared with NW children. CONCLUSIONS: Our results show reduced sleep amount and quality in otherwise healthy OW children. The lower stage R amount and changes involving stage N3 throughout the night suggest that OW in childhood is associated with modifications not only in sleep duration, but also in the ongoing night time patterns of NREM sleep and REM sleep stages.

Reconstruction of surface potential from Kelvin probe force microscopy images.

We present an algorithm for reconstructing a sample surface potential from its Kelvin probe force microscopy (KPFM) image. The measured KPFM image is a weighted average of the surface potential underneath the tip apex due to the long-range electrostatic forces. We model the KPFM measurement by a linear shift-invariant system where the impulse response is the point spread function (PSF). By calculating the PSF of the KPFM probe (tip+cantilever) and using the measured noise statistics, we deconvolve the measured KPFM image to obtain the surface potential of the sample.The reconstruction algorithm is applied to measurements of CdS-PbS nanorods measured in amplitude modulation KPFM (AM-KPFM) and to graphene layers measured in frequency modulation KPFM (FM-KPFM). We show that in the AM-KPFM measurements the averaging effect is substantial, whereas in the FM-KPFM measurements the averaging effect is negligible.