Variation In Activity Levels Research Articles

Decay time estimate for LEO spacecraft

The growing concerns posed by orbital debris represent a serious threat to the future of space operations in low Earth orbit. With the goal of limiting the formation of new debris, space agencies are proposing international guidelines that satellites should be able to deorbiting within 25 years of the end of their operational life. Orbital decay is typically caused by atmospheric drag, so estimating the decay time of a satellite subject to drag is critical to assessing whether the guidelines are met. However, such estimate is a very challenging task because of the difficulty of accurately modeling atmospheric properties and because of the coupling of orbital dynamics with spacecraft attitude. In this paper, a simplified algorithm based on the King-Hele formulation is proposed to rapidly estimate the decay time of an orbiting satellite without imposing any assumptions on the spacecraft’s nominal size, mass, geometry or attitude. The algorithm accounts for the effect of solar activity level variations on atmospheric properties and drag coefficient through an iterative procedure and can be applied to any object in orbit. Numerical tests show that the predictions in terms of decay times are very accurate for satellites that are quite different in size and geometry, including the presence of an aerodynamic drag augmentation system such as a drag sail.

Going urban: variation in personality traits of an invasive species along an urbanization gradient

Abstract The fast-growing expansion of urban areas pose severe pressures on wildlife. However, some generalist native mammals thrive in urbanized landscapes, while invasive alien species (IAS) are often more abundant in cities than in rural habitats. Variation in phenotypes—such as differences in personality traits—can influence the probability to colonize anthropized areas, especially in the case of IAS where certain traits are related to invasion success. Here, we investigated the expression of activity, exploration, and social tendency in the invasive alien Eastern Gray Squirrel (Sciurus carolinensis) in replicated study sites along a rural–urban gradient in Northern Italy. Personality traits expression was estimated using an open field test (OFT) followed by a mirror image stimulation (MIS) test. We found that squirrels were more active in urban than in suburban and rural sites, and behaved more sociable in urban than in suburban sites. Conversely, exploration did not differ along the gradient. Results also reveal the presence of a behavioral syndrome: activity (OFT), social tendency, and activity–exploration (MIS). We suggest that variation in activity level and social behavior in urban habitats could favor some species to respond positively to urbanization. This study sheds light on the underexplored personality–urbanization relationship in IAS, helping to understand the complex process of invasion.

Vegan and Vegetarian Soups Are Excellent Sources of Cholinesterase Inhibitors.

The cholinesterase theory stands as the most popular worldwide therapy for Alzheimer's disease (AD). Given the absence of a cure for AD, a plant-based diet has been repeatedly shown as positive in the prevention of AD, including exploring ready-made products in stores and the development of new functional foods. This study compared the anti-acetyl- and butyrylcholinesterase activity of thirty-two Polish market soups and five newly formulated soups intended to be functional. Additionally, the research aimed to assess the significance of animal content, distinguishing between vegan and vegetarian options, in cholinesterase inhibition. The anticholinesterase activity was investigated using a spectrophotometric method, and the inhibitory activity was expressed as % inhibition of the enzyme. The study categorized soups into three groups based on ingredients: those containing animal-derived components, vegetarian soups and vegan soups. Soups exhibited varying levels of activity against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), indicating differences in their compositions. Composition appeared to be the primary factor influencing anticholinesterase activity, as soups within each group showed significant variability in activity levels. While some commercial soups demonstrated notable anticholinesterase activity, they did not surpass the effectiveness of the optimized soups developed in the laboratory. Certain ingredients were associated with higher anticholinesterase activity, such as coconut, potato, onion, garlic, parsley and various spices and herbs. Vegetarian and vegan soups exhibited comparable or even superior anticholinesterase activity compared to animal-derived soups, highlighting the importance of plant-based ingredients. The study underscores the need for further research to explore the mechanisms underlying the anticholinesterase activity of soups, including the impact of ingredient combinations and processing methods.

Bis‐Ureido‐Substituted Benzenesulfonamides: Evaluation of Their Antibacterial, Anticholinesterase, and Cytotoxicity Properties

AbstractIn this study, we present the re‐synthesis of a series of twelve bis‐ureido‐substituted benzenesulfonamides, focusing on their potential as antibacterial, anticholinesterase, and cytotoxic agents. First, the antibacterial assessment of these compounds indicated varying activity levels across different bacterial strains, with S. aureus displaying resistance to all compounds, while compounds 9 and 11 exhibited promise against E. faecalis with a MIC value of 31.25 μg/mL. Additionally, P. aeruginosa showed resistance to compounds containing 4‐aminobenzene sulfonamides, whereas derivatives such as (8–11) and compound 19 displayed notable activity against E. coli, comparable to Ampicillin. Second, their anticholinesterase activities were examined, with a focus on their potential role in addressing neurological disorders, particularly Alzheimer′s disease. The findings indicated that all synthesized compounds showed a significant inhibitory effect on both AChE and BChE enzymes. Compound 11 demonstrated the most effective inhibition on the AChE enzyme with an IC50 value of 0.2160±0.09 nM, while compound 18 exhibited the most potent inhibition on the BChE enzyme with an IC50 value of 0.2257±0.06 nM. Finally, cytotoxicity studies were conducted across various cell lines, including breast, lung, and prostate cancer cells and normal cells. The results revealed that compound 12 emerged as the most potent tested compound against breast cancer cells with no cytotoxic effect on CRL‐4010 normal breast epithelial cells. The research presented here not only highlights the multifaceted pharmacological potential of bis‐ureido‐substituted benzenesulfonamides, but also indicates their potential as versatile compounds for antibacterial, anticholinesterase, and cytotoxicity applications, opening up new avenues for drug discovery and development.

The impact of differential transposition activities of autonomous and nonautonomous hAT transposable elements on genome architecture and gene expression in Caenorhabditis inopinata.

Transposable elements are DNA sequences capable of moving within genomes and significantly influence genomic evolution. The nematode Caenorhabditis inopinata exhibits a much higher transposable element copy number than its sister species, Caenorhabditis elegans. In this study, we identified a novel autonomous transposable element belonging to the hAT superfamily from a spontaneous transposable element-insertion mutant in C. inopinata and named this transposon Ci-hAT1. Further bioinformatic analyses uncovered 3 additional autonomous hAT elements-Ci-hAT2, Ci-hAT3, and Ci-hAT4-along with over 1,000 copies of 2 nonautonomous miniature inverted-repeat transposable elements, mCi-hAT1 and mCi-hAT4, likely derived from Ci-hAT1 and Ci-hAT4 through internal deletion. We tracked at least 3 sequential transpositions of Ci-hAT1 over several years. However, the transposition rates of the other 3 autonomous hAT elements were lower, suggesting varying activity levels. Notably, the distribution patterns of the 2 miniature inverted-repeat transposable element families differed significantly: mCi-hAT1 was primarily located in the chromosome arms, a pattern observed in the transposable elements of other Caenorhabditis species, whereas mCi-hAT4 was more evenly distributed across chromosomes. Additionally, interspecific transcriptome analysis indicated that C. inopinata genes with upstream or intronic these miniature inverted-repeat transposable element insertions tend to be more highly expressed than their orthologous genes in C. elegans. These findings highlight the significant role of de-silenced transposable elements in driving the evolution of genomes and transcriptomes, leading to species-specific genetic diversity.

Intra- and Inter-group Optimal Transport for User-Oriented Fairness in Recommender Systems

Recommender systems are typically biased toward a small group of users, leading to severe unfairness in recommendation performance, i.e., User-Oriented Fairness (UOF) issue. Existing research on UOF exhibits notable limitations in two phases of recommendation models. In the training phase, current methods fail to tackle the root cause of the UOF issue, which lies in the unfair training process between advantaged and disadvantaged users. In the evaluation phase, the current UOF metric lacks the ability to comprehensively evaluate varying cases of unfairness. In this paper, we aim to address the aforementioned limitations and ensure recommendation models treat user groups of varying activity levels equally. In the training phase, we propose a novel Intra- and Inter-GrOup Optimal Transport framework (II-GOOT) to alleviate the data sparsity problem for disadvantaged users and narrow the training gap between advantaged and disadvantaged users. In the evaluation phase, we introduce a novel metric called ?-UOF, which enables the identification and assessment of various cases of UOF. This helps prevent recommendation models from leading to unfavorable fairness outcomes, where both advantaged and disadvantaged users experience subpar recommendation performance. We conduct extensive experiments on three real-world datasets based on four backbone recommendation models to prove the effectiveness of ?-UOF and the efficiency of our proposed II-GOOT.

In Vitro Evaluation of Essential Oils and Saturated Fatty Acids for Repellency against the Old-World Sand Fly, Phlebotomus papatasi (Scopoli) (Diptera: Psychodidae).

The sand fly, Phlebotomus papatasi (Scopoli, 1786), is a major vector for Leishmania major in the Middle East, which has impacted human health and US military operations in the area, demonstrating the need to develop effective sand fly control and repellent options. Here, we report the results of spatial repellency and avoidance experiments in a static air olfactometer using the female P. papatasi testing essential oils of Lippia graveolens (Mexican oregano), Pimenta dioica (allspice), Amyris balsamifera (amyris), Nepeta cataria (catnip), Mentha piperita (peppermint), and Melaleuca alternifolia (tea tree); the 9-12 carbon saturated fatty acids (nonanoic acid, decanoic acid, undecanoic acid, and dodecanoic acid); and the synthetic repellents DEET and IR3535. The materials applied at 1% exhibited varying activity levels but were not significantly different in mean repellency and avoidance from DEET and IR3535, except in regards to nonanoic acid. Some materials, particularly nonanoic and undecanoic acids, produced sand fly mortality. The observed trends in mean repellency over exposure time included the following: (1) P. dioica oil, M. alternifolia oil, decanoic acid, undecanoic acid, DEET, and IR3535 exhibited increasing mean repellency over time; (2) oils of N. cataria, A. balsamifera, M. piperita, and dodecanoic acid exhibited relatively constant mean repellency over time; and (3) L. graveolens oil and nonanoic acid exhibited a general decrease in mean repellent activity over time. These studies identified the essential oils of N. cataria and A. balsamifera as effective spatial repellents at reduced concentrations compared to those of DEET. Additional research is required to elucidate the modes of action and potential synergism of repellents and essential oil components for enhanced repellency activity.

Unraveling the link: locomotor activity exerts a dual role in predicting Achilles tendon healing and boosting regeneration in mice.

Tendon disorders present significant challenges in the realm of musculoskeletal diseases, affecting locomotor activity and causing pain. Current treatments often fall short of achieving complete functional recovery of the tendon. It is crucial to explore, in preclinical research, the pathways governing the loss of tissue homeostasis and its regeneration. In this context, this study aimed to establish a correlation between the unbiased locomotor activity pattern of CRL:CD1 (ICR) mice exposed to uni- or bilateral Achilles tendon (AT) experimental injuries and the key histomorphometric parameters that influence tissue microarchitecture recovery. The study involved the phenotyping of spontaneous and voluntary locomotor activity patterns in male mice using digital ventilated cages (DVC®) with access to running wheels either granted or blocked. The mice underwent non-intrusive 24/7 long-term activity monitoring for the entire study period. This period included 7 days of pre-injury habituation followed by 28 days post-injury. The results revealed significant variations in activity levels based on the type of tendon injury and access to running wheels. Notably, mice with bilateral lesions and unrestricted wheel access exhibited significantly higher activity after surgery. Extracellular matrix (ECM) remodeling, including COL1 deposition and organization, blood vessel remodeling, and metaplasia, as well as cytological tendon parameters, such as cell alignment and angle deviation were enhanced in surgical (bilateral lesion) and husbandry (free access to wheels) groups. Interestingly, correlation matrix analysis uncovered a strong relationship between locomotion and microarchitecture recovery (cell alignment and angle deviation) during tendon healing. Overall, this study highlights the potential of using mice activity metrics obtained from a home-cage monitoring system to predict tendon microarchitecture recovery at both cellular and ECM levels. This provides a scalable experimental setup to address the challenging topic of tendon regeneration using innovative and animal welfare-compliant strategies.

Assessing human internal exposure to chemicals at different physical activity levels: A physiologically based kinetic (PBK) model incorporating metabolic equivalent of task (MET)

Physical activity levels have the potential to impact human internal exposure to environmental chemicals. However, the current lack of simple modeling approaches hinders the high-throughput screening of chemical exposure at different physical activity levels. To address this gap, this study proposes a straightforward model for assessing human internal exposure to chemicals. Our approach is based on the physiologically based kinetic (PBK) model and utilizes the metabolic equivalent of task (MET) to characterize internal exposure to chemicals at varying activity levels. To facilitate the application of this model, we have developed an Excel-based operation tool, allowing users to easily modify the MET value and generate simulation results for different physical activity levels. The simulation results demonstrate that as physical activity levels increase, the biotransfer factors (BTFs) of chemicals decrease, suggesting that higher physical activity levels reduce the bioaccumulation potential of chemicals. The intensified physical activity enhances the overall elimination kinetics of chemicals from the human body. However, the simulated concentrations of chemicals in the human body increase with higher physical activity levels, due to the significantly increased external exposure to chemicals, such as through inhalation. Our proposed modeling approach, along with the operational tool, enables high-throughput simulation of human chronic internal exposure to chemicals at different physical activity levels, where the findings can assist in screening chemicals for further health risk assessment. To accomplish this, the model incorporates certain assumptions and utilizes generic model input values. However, due to the intricate nature of the interaction between external and internal exposures at different physical activity levels, validating the simulation through experimental studies becomes challenging and is not performed in this study. For future studies, we recommend incorporating more MET-related physiological input variables, improving energy balance estimates, comprehending external exposure estimates, and conducting cohort studies to enhance and validate the proposed modeling approach.

In Situ Mapping of Activity Distribution of V(II)/V(III) and Onset Potential Distribution of Hydrogen Evolution Side Reaction in Vanadium Flow Batteries.

Vanadium flow batteries (VFBs) face a challenge with the low reaction rates of the V(II)/V(III) redox couple, which limits the performance of VFBs. Additionally, the negative electrode in VFBs is often accompanied by the persistent hydrogen evolution reaction (HER), which is difficult to eliminate. Therefore, understanding the spatial distribution of activity on the negative electrode and the HER side reaction on the electrode surface is of critical importance. This study proposes a weak measurement imaging method to characterize the spatial distribution of surface activity and HER onset potential on the negative electrode in VFBs). This method enables the visualization and in situ detection of key parameters such as the absolute values of |ipa |, |ipc |, |∆E|, |ipc /ipa |, and the HER onset potential. By comparing three different types of graphite felts with varying activity levels, it validates the feasibility of this method. Furthermore, electrochemical stability tests are conducted to study the electrodes repeatability, uniformity, and durability. This method holds promise in guiding the design of electrodes with enhanced activity, good reversibility, minimized HER side reactions, and uniform distribution.

Alpha and beta spillover in liquid scintillation counting analysis of urine samples.

Rapid detection and quantification of gross alpha/beta-emitting radionuclides by liquid scintillation counting (LSC) is vital in guiding response to a nuclear or radiological incidents. Liquid scintillation counters use signal pulse shape to discriminate alpha and beta events in samples but require precise optimization to minimize the spillover, or misclassification, of those events. In this study, samples at varying activity levels were analyzed by LSC to determine the effect of activity level, emitter type, and sample matrix on spillover. Analysis proved a matrix effect and a direct correlation of activity level on spillover percentage for both alpha and beta emitting-nuclides.

Bitcoin under the microscope

This paper explores and describes historical on-chain transaction data recorded on the Bitcoin blockchain, constructs a panel of all individual Bitcoin users, and computes their balances in the cross-section and over time. We run clustering algorithms to combine addresses that belong to the same user into wallets and we find that using wallets over addresses as the unit of analysis allows for more economically meaningful interpretations of user behavior. We identify and divide wallets into user categories – miners, exchanges, services, retail wallets and receiving-only addresses – and observe varying activity levels and balances in the cross-section and over time, corresponding to their intended role in the Bitcoin network. Our findings also suggest heterogeneity in financial performance across user categories with miners exhibiting higher realized returns relative to exchanges and retail users.

Spatial Patterning of Micromotor Aggregation and Flux.

Using a spatially varying light pattern with light activated semi-conductor based magnetic TiO2 micromotors, we study the difference in micromotor flux between illuminated and non-illuminated regions in the presence and absence of an applied magnetic field. We find that the magnetic field enhances the flux of the motors which we attribute to a straightening of the micromotor trajectories which decreases the time they spend in the illuminated region. We also demonstrate spatially patterned light-induced aggregation of the micromotors and study its time evolution at various micromotor concentrations. Although light induced aggregation has been observed previously, spatial patterning of aggregation demonstrates a further means of control which could be relevant to swarm control or self-assembly applications. Overall, these results draw attention to the effect of trajectory shape on the flux of active colloids as well as the concentration dependence of aggregation and its time dependence within a spatially patterned region, which is not only pertinent to self-assembly and swarm control, but also provides insight into the behavior of active matter systems with spatially varying activity levels.

Appraisal of Fungus-Derived Xanthoquinodins as Broad-Spectrum Anti-Infectives Targeting Phylogenetically Diverse Human Pathogens.

Xanthoquinodins make up a distinctive class of xanthone-anthraquinone heterodimers reported as secondary metabolites from several fungal species. Through a collaborative multi-institutional screening program, a fungal extract prepared from a Trichocladium sp. was identified that exhibited strong inhibitory effects against several human pathogens (Mycoplasma genitalium, Plasmodium falciparum, Cryptosporidium parvum, and Trichomonas vaginalis). This report focuses on one of the unique samples that exhibited a desirable combination of biological effects: namely, it inhibited all four test pathogens and demonstrated low levels of toxicity toward HepG2 (human liver) cells. Fractionation and purification of the bioactive components and their congeners led to the identification of six new compounds [xanthoquinodins NPDG A1-A5 (1-5) and B1 (6)] as well as several previously reported natural products (7-14). The chemical structures of 1-14 were determined based on interpretation of their 1D and 2D NMR, HRESIMS, and electronic circular dichroism (ECD) data. Biological testing of the purified metabolites revealed that they possessed widely varying levels of inhibitory activity against a panel of human pathogens. Xanthoquinodins A1 (7) and A2 (8) exhibited the most promising broad-spectrum inhibitory effects against M. genitalium (EC50 values: 0.13 and 0.12 μM, respectively), C. parvum (EC50 values: 5.2 and 3.5 μM, respectively), T. vaginalis (EC50 values: 3.9 and 6.8 μM, respectively), and P. falciparum (EC50 values: 0.29 and 0.50 μM, respectively) with no cytotoxicity detected at the highest concentration tested (HepG2 EC50 > 25 μM).

Relationship Between Activity Level and Knee Function Is Influenced by Negative Affect in Patients Undergoing Cell Therapy for Articular Cartilage Defects in the Knee.

Increased activity level is generally reported to be positively related to improved knee function after knee surgery. However, little research has been conducted into this relationship on an individual patient basis, or the influence of demographic and psychosocial factors such as patient affect-the subjective experience of emotion. The relationship between postoperative activity level and knee function will vary between patients and will be influenced by the patients' affect and demographic characteristics. Cohort study; Level of evidence, 3. Activity, knee function, demographic, and affect data were collected from patients enrolled in an ongoing trial for the treatment of articular cartilage lesions at preoperative and 2-, 12-, and 15-month postoperative points. Quantile mixed regression modeling was used to determine the patient-to-patient variation in activity level and knee function. Multiple linear regression and partial correlation analyses were performed to determine whether demographic characteristics and patient affect were associated with this variation. A total of 62 patients were included in the study (23 female; 39 male; mean age, 38.3 ± 9.5 years). We found substantial variation between patients in the relationship between activity level and knee function, with most patients (n = 56) demonstrating a positive relation (positive slope), but 6 patients demonstrating a negative relation (negative slope). A negative affect (NA) score was significantly correlated with the slope between activity level and knee function (r S = -0.30; P = .018) and was a significant individual predictor of knee function at 15 months postoperatively (coefficient = -3.5; P = .025). Our results suggest that the relationship between activity level and knee function varies between patients. The patients with a higher NA score were likely to report smaller improvements in knee function with increasing activity levels compared with those with a lower NA score.

Algerian and European hedgehogs cohabiting in periurban environments: spatial behaviour and habitat use

Habitat fragmentation is one of the most important threats to biodiversity in the last decades. Numerous species are forced to adapt to human presence as urbanization keeps increasing. Some studies show the impact of habitat changes in various species; however, there is little knowledge about the effect of habitat disturbance on hedgehogs in the Iberian Peninsula. We radio tracked 31 male hedgehogs: 14 European hedgehogs and 17 Algerian hedgehogs, being 18 individuals indigenous and 13 translocated. We analysed their home ranges, spatial behaviour and habitat use in a suburban area of Valencia City, Spain, where the two species coexist. Our results show that there are phenologic variations of activity levels, which differ between species, being maximum in spring for the European hedgehog and in summer for the Algerian hedgehog. We did not detect a territorial behaviour or interspecific spatial competition. However, we could detect a clear “release effect”, with translocated individuals presenting increased home range sizes and activity levels as they explore the unknown environment. Furthermore, we found that both species showed a clear preference for the pine forest habitat, avoiding all other habitat types, especially those with high human presence. Our results also suggest that the European hedgehog has a more generalist character than the Algerian hedgehog regarding habitat use. In conclusion, this study highlights the importance of conserving a connected mosaic of green patches in urbanized environments for the conservation of hedgehog populations.

Antibacterial, Antioxidant Potency, and Chemical Composition of Essential Oils from Dried Powdered Leaves and Flowers of Hypericum revolutum subsp. keniense (Schweinf.).

Hypericum revolutum subsp. keniense is a plant mainly used to treat diarrhoea, rheumatism, nervous disorders, and wounds in African traditional medicine. The objective of the current work was to establish antibacterial, antioxidant potency, and chemical composition of essential oil from the leaves and flowers of Hypericum revolutum subsp. keniense. The oils were isolated by steam distillation. Antibacterial activity against methicillin-resistant Staphylococcus aureus, Staphylococcus aureus (ATCC 12393), Escherichia coli (ATCC 25922), Acinetobacter baumannii (ATTC 19606), Salmonella enteritidis (NCTC12023), Salmonella typhimurium (ATCC 14028), Pseudomonas aeruginosa (ATCC 15442), and Haemophilus influenzae (ATCC 49766) was carried out by agar disk diffusion and microtiter broth dilution methods. Antioxidant activities of the essential oils were examined by different methods, DPPH, FRAP, and H2O2 assays. Chemical characterization was performed using gas chromatography interfaced with mass spectrometry, Fourier-transform infra-red (FTIR) spectroscopy, and quantification of phenolics and flavonoids by Folin-Ciocalteu reagent and aluminium nitrate, respectively. The oils showed potential antibacterial activity with mean zone of inhibition ranging from 20.67 ± 0.33 to 32.00 ± 1.00 mm at 100% oil concentration against the tested bacteria. Furthermore, the minimum inhibitory concentrations (MICs) in all the tested microorganisms were in the range from 250 to 15.6250 μg/ml. The essential oils derived from the leaves revealed varied antioxidant activity levels with the different methods of assay. The IC50 of values obtained from the three methods, DPPH, FRAP, and H2O2 were ˃1000 μg/ml, 0.31 μg/ml, and 12.33 μg/ml, respectively. Caryophyllene (22.1%) and 2, 3, 4-trimethylhexane were the major chemical components of the essential oils derived from the leaves and flowers, respectively. FTIR spectroscopy of the essential oils from the leaves and flowers showed similarity at peaks for hydroxyl, unsaturated olefinic, and amine functional groups. Further findings indicated that the total phenolic and flavonoid contents essential oils derived from leaves were 130.4 6 ± 10.5 mg GAE/g dry weight and 0.911 ± 0.04 mg CE/g dry weight, respectively. It was therefore concluded that essential oils from the leaves and flowers of H. revolutum subsp. keniense have compounds that have antibacterial and antioxidant potency.

Viral marketing branching processes

We consider the inherent timeline structure of the appearance of content in online social networks (OSNs) while studying content propagation. We model the propagation of a post/content of interest by an appropriate multi-type branching process. The branching process allows one to predict the emergence of global macro properties (e.g., the spread of a post in the network) from the laws and parameters that determine local interactions. The local interactions largely depend upon the timeline (an inverse stack capable of holding many posts and one dedicated to each user) structure and the number of friends (i.e., connections) of users, etc. We explore the use of multi-type branching processes to analyze the viral properties of the post, e.g., to derive the expected number of shares, the probability of virality of the content, etc.In OSNs, the new posts push down the existing contents in timelines, which can greatly influence content propagation; our analysis considers this influence. We find that one leads to draw incorrect conclusions when the timeline (TL) structure is ignored: (a) for instance, even less attractive posts are shown to get viral; (b) ignoring TL structure also indicates erroneous growth rates. More importantly, one cannot capture some interesting paradigm shifts/phase transitions; for example, virality chances are not monotone with network activity parameter, as shown by analysis including TL influence.In the last part, we integrate the online auctions into our viral marketing model. We study the optimization problem considering real-time bidding. We again compared the study with and without considering the TL structure for varying activity levels of the network. We find that the analysis without TL structure fails to capture the relevant phase transitions, thereby making the study incomplete.

302 MONITORING FALLS RISK IN THE COMMUNITY USING AN IMPLANTABLE CARDIAC MONITOR WITH EMBEDDED ACCELEROMETER

Abstract Background Falls are the most common cause of injury amongst older adults. Falls can lead to hospitalisation, functional decline and are associated with increased morbidity and mortality. The holy grail for clinicians would be to predict increased likelihood of falls occurring and intervene before the event. Understanding underlying dynamic biophysiological changes may therefore inform novel predictor models and falls prevention. This study examines activity and cardiac data acquired from an implanted Medtronic Reveal LINQ™ Insertable Cardiac Monitor (ICM) with an embedded tri-axial accelerometer. Methods Thirty participants with at least one unexplained fall in the previous two years were prospectively recruited. All met criteria for ICM insertion following comprehensive assessment. Participants were followed for one year and attended every three-months for cardiac and gait assessment. Information pertaining to activity levels, posture changes and cardiac parameters were collected daily from the device. Summary metrics and trends were collected for inclusion in a continual assessment of falls risk. Results Mean age of participants was 68.0 years (±9.3). 19/30 (63.3%) were female. 22/30 (73.3%) had at least one cardiovascular condition documented in their medical history. There was seasonal variation in activity levels. Twelve participants had falls and cardiovascular, gait and activity variables were examined at the time of a fall to determine any trends in biophysiological changes. Conclusion Causes of falls are usually multifactorial. A holistic approach is necessary to manage and minimise risk factors. The use of an ICM with an embedded tri-axial accelerometer allows clinicians to formulate an algorithm to determine if a person is at an increased risk of falling based on biophysiological changes. This may create an opportunity for falls to be predicted and prevented.

At-home end-tidal carbon dioxide measurement in children with invasive home mechanical ventilation.

Carbon dioxide concentration trending is used in chronic management of children with invasive home mechanical ventilation (HMV) in clinical settings, but options for end-tidal carbon dioxide (EtCO2 ) monitoring at home are limited. We hypothesized that a palm-sized, portable endotracheal capnograph (PEC) that measures EtCO2 could be adapted for in-home use in children with HMV. We evaluated the internal consistency of the PEC by calculating an intraclass correlation coefficient of threeback-to-back breaths by children (0-17 years) at baseline health in the clinic. Pearson's correlation was calculated for PEC EtCO2 values with concurrent mean values of in-clinic EtCO2 and transcutaneous CO2 (TCM) capnometers. The Bland-Altman test determined their level of agreement. Qualitative interviews and surveys assessed usability and acceptability by family-caregivers at home. CO2 values were collected in awake children in varied activity levels and positions (N = 30). The intraclass correlation coefficient for the PEC was 0.95 (p < 0.05). The correlation between the PEC and in-clinic EtCO2 device was 0.85 with a mean difference of -3.8 mmHg and precision of ±1.1 mmHg. The correlation between the PEC and the clinic TCM device was 0.92 with a mean difference of 0.2 mmHg and precision of ±1.0. Family-caregivers (N = 10) trialed the PEC at home; all were able to obtain measurements at home while children were awake and sometimes asleep. A portable, noninvasive device for measuring EtCO2 was feasible and acceptable, with values that trend similarly to currently in-practice, outpatient models. These devices may facilitate monitoring of EtCO2 at home in children with invasive HMV.