Single Aggregation Research Articles

Machine Learning Differential Privacy With Multifunctional Aggregation in a Fog Computing Architecture

Data aggregation plays an important role in the Internet of Things, and its study and analysis has resulted in a range of innovative services and benefits for people. However, the privacy issues associated with raw sensory data raise significant concerns due to the sensitive nature of the user information it often contains. Thus, numerous schemes have been proposed over the last few decades to preserve the privacy of users’ data. Most methods are based on encryption technology, which is computationally and communicationally expensive. In addition, most methods can only handle a single aggregation function. Therefore, in this paper, we propose a multifunctional data aggregation method with differential privacy. The method is based on machine learning and can support a wide range of statistical aggregation functions, including additive and non-additive aggregation. It operates within a fog computing architecture, which extends cloud computing to the edge of the network, alleviating much of the computational burden on the cloud server. And, by only reporting the results of the aggregation to the server, communication efficiency is improved. Extensive experimental results show that the proposed method not only answers flexible aggregation queries that meet diversified aggregation goals, but also produces aggregation results with high accuracy.

Particle Interactions Mediated by Dynamical Networks: Assessment of Macroscopic Descriptions

We provide a numerical study of the macroscopic model of Barré et al. (Multiscale Model Simul, 2017, to appear) derived from an agent-based model for a system of particles interacting through a dynamical network of links. Assuming that the network remodeling process is very fast, the macroscopic model takes the form of a single aggregation–diffusion equation for the density of particles. The theoretical study of the macroscopic model gives precise criteria for the phase transitions of the steady states, and in the one-dimensional case, we show numerically that the stationary solutions of the microscopic model undergo the same phase transitions and bifurcation types as the macroscopic model. In the two-dimensional case, we show that the numerical simulations of the macroscopic model are in excellent agreement with the predicted theoretical values. This study provides a partial validation of the formal derivation of the macroscopic model from a microscopic formulation and shows that the former is a consistent approximation of an underlying particle dynamics, making it a powerful tool for the modeling of dynamical networks at a large scale.

Long-term assessment of whale shark population demography and connectivity using photo-identification in the Western Atlantic Ocean.

The predictable occurrence of whale sharks, Rhincodon typus, has been well documented in several areas. However, information relating to their migratory patterns, residency times and connectivity across broad spatial scales is limited. In the present study photo-identification data is used to describe whale shark population structure and connectivity among known aggregation sites within the Western Central Atlantic Ocean (WCA). From 1999 to 2015, 1,361 individuals were identified from four distinct areas: the Yucatan Peninsula, Mexico (n = 1,115); Honduras (n = 146); northern Gulf of Mexico, United States (n = 112), and Belize (n = 49). Seasonal patterns in whale shark occurrence were evident with encounters occurring in the western Caribbean Sea earlier in the year than in the GOM. There was also a significant sex bias with 2.6 times more males present than females. Seventy sharks were observed in more than one area and the highest degree of connectivity occurred among three aggregation sites along the Mesoamerican Reef. Despite this, the majority of resightings occurred in the area where the respective sharks were first identified. This was true for the WCA as a whole, with the exception of Belize. Site fidelity was highest in Mexico. Maximum likelihood modelling resulted in a population estimate of 2,167 (95% c.i. 1585.21–2909.86) sharks throughout the entire region. This study is the first attempt to provide a broad, regional population estimate using photo-identification data from multiple whale shark aggregations. Our aim is to provide population metrics, along with the description of region-scale connectivity, that will help guide conservation action in the WCA. At a global level, rapidly growing photographic databases are allowing for researchers to look beyond the description of single aggregation sites and into the ocean-scale ecology of this pelagic species.

Demand forecasting by temporal aggregation: Using optimal or multiple aggregation levels?

Recent advances have demonstrated the benefits of temporal aggregation for demand forecasting, including increased accuracy, improved stock control and reduced modelling uncertainty. With temporal aggregation a series is transformed, strengthening or attenuating different elements and thereby enabling better identification of the time series structure. Two different schools of thought have emerged. The first focuses on identifying a single optimal temporal aggregation level at which a forecasting model maximises its accuracy. In contrast, the second approach fits multiple models at multiple levels, each capable of capturing different features of the data. Both approaches have their merits, but so far they have been investigated in isolation. We compare and contrast them from a theoretical and an empirical perspective, discussing the merits of each, comparing the realised accuracy gains under different experimental setups, as well as the implications for business practice. We provide suggestions when to use each for maximising demand forecasting gains.

Inter‐annual variation of the spawning aggregations of the white‐streaked grouper Epinephelus ongus, in relation to the lunar cycle and water temperature fluctuation

AbstractThe white‐streaked grouper, Epinephelus ongus (Serranidae), which forms spawning aggregations at specific times and sites, has been traditionally targeted by local fishers in the Yaeyama Islands, Okinawa. This study examined the long‐term dynamics of the population and the spawning aggregation of E. ongus, based on the historical catch data for a 20‐yr period. The continuous declines of the catch data suggested a substantial decrease in the population. The analysis of the daily catch data, which reflect the approximate volumetric fluctuation of the spawning aggregation, demonstrated that the distinctive peaks of daily catches appeared consistently over a 20‐yr span at the last quarter moon in the spawning season, in synchrony with the lunar phase as a spawning cue of the species. Contrary to this consistency, there were inter‐annual variations of spawning aggregation formation, which formed once or twice in the two consecutive months in the lunar calendar. The present study indicated that the water temperature before the aggregation period dictated not the only timing of the first spawning aggregation, but also the frequency of spawning aggregation and that the abundance between the first and the second spawning aggregation, represented by catch data, were negatively correlated. Together with previous evidence of gonadal histology, the findings indicated that water temperatures affect the gonadal maturation in the spawning population and control spawning aggregation formation. These facts imply that most individuals join in only a single spawning aggregation in the course of the year and highlight the importance of the spawning aggregation for reproduction of E. ongus.

Protein aggregation activates erratic stress response in dietary restricted yeast cells.

Chronic stress and prolonged activation of defence pathways have deleterious consequences for the cell. Dietary restriction is believed to be beneficial as it induces the cellular stress response machinery. We report here that although the phenomenon is beneficial in a wild-type cell, dietary restriction leads to an inconsistent response in a cell that is already under proteotoxicity-induced stress. Using a yeast model of Huntington’s disease, we show that contrary to expectation, aggregation of mutant huntingtin is exacerbated and activation of the unfolded protein response pathway is dampened under dietary restriction. Global proteomic analysis shows that when exposed to a single stress, either protein aggregation or dietary restriction, the expression of foldases like peptidyl-prolyl isomerase, is strongly upregulated. However, under combinatorial stress, this lead is lost, which results in enhanced protein aggregation and reduced cell survival. Successful designing of aggregation-targeted therapeutics will need to take additional stressors into account.

The Non-Use of Sleeping Substrate by the Sympatric BeesAmegilla florea urensandA. senahai senahai(Hymenoptera: Apoidea)

Few studies have addressed the use of overnight substrate by congeneric bee species, although sleeping bees with other insect taxa or other bee families have been found to share the same substrates. We observed the sleeping aggregations of two sympatric bees, Amegilla florea urens and A. senahai senahai, to determine whether they shared the same substrates for sleeping on Ishigaki Island, Okinawa Prefecture, Japan. Many sleeping aggregations were found in broad-leaved deciduous forests and were patchily distributed along a pathway in broad-leaved evergreen forests in June for 2 years. Overnight aggregations formed on the leaves of monocotyledons or the fine roots of trees exposed on the slope of a bare cliff along the edge of the pathway. Neither species showed preference for any particular substrates. Over 2 years, we found 1 A. f. urens male aggregation, 6 A. s. senahai male aggregations, and 88 A. f. urens female aggregations. A sleeping site with aggregations of both Amegilla bee species was observed only once. Although no physical contact or mating approach es among sleeping individuals in each species were observed during the night, conspecific individuals slept close to other individuals in the aggregation. We suggest that single species aggregation would have an advantage for conspecifics to increase the night survival rate by sharing information such as predator attack.

A survey on anti-thrombosis treatment plans for elderly patients with non-valvular atrial fibrillation in the different divisions of internal medicine

Objective To identify anti-thrombosis treatment plans for hospitalized elderly patients with non-valvular atrial fibrillation adopted by the different divisions of the internal medicine department. Methods Retrospective data on CHADS2 scores and the frequencies of anti-platelet aggregation and anticoagulation medication in 990 elderly hospitalized patients with non-valvular atrial fibrillation in the different divisions of internal medicine were analyzed. Results Most of the 990 subjects were located in Cardiology (357 cases, 36.1%), Geriatrics (131 cases, 13.2%), the Cadres' Ward (162 cases, 16.4%) and Neurology (138 cases, 13.9%), while a minority stayed in Emergency Medicine (70 cases, 7.0%), Respiratory Medicine (56 cases, 5.7%), Endocrinology (38 cases, 3.8%), Gastroenterology (20 cases, 2.0%) and Nephrology (18 cases, 1.8%). Of the 573 cases with a CHADS2 score of 2 or higher, 58.1% (333/573) received single antiplatelet aggregation therapy, 24.1% (138/573) received dual antiplatelet aggregation therapy and only 14% (80/573) received anticoagulation therapy (warfarin + new oral anticoagulants). The proportion of patients receiving anticoagulation (warfarin) was relatively high in Cardiology (20.1%, 43/214), Geriatrics (17.2%, 10/58) and the Cadres' Ward (13.1%, 11/84). Conclusions The use of anticoagulation therapy in elderly patients with non-valvular atrial fibrillation is generally infrequent and is relatively more commonly used in Cardiology, Geriatrics, and the Cadres' Ward than in other divisions of internal medicine. Key words: Atrial fibrillation; Platelet aggregation inhibitors

Eusocial bee male aggregations: spatially and temporally separated but genetically homogenous

AbstractMale insects mostly aggregate near sites where sexually reproductive virgin females are found and where mating occur. This reproductive strategy is quite common in Hymenoptera and appears to decrease the chances of inbreeding. In Hymenoptera, inbred mating frequently result in sterile diploid males. Production of diploid males may reach high proportions in small bee populations, and it usually lead to population extinction within a small number of generations. Aggregation of males during a short period of time allow the mixing of local genes. In this paper, we analyzed male aggregations of Tetragonisca angustula (Latreille) (Hymenoptera: Apidae), a eusocial stingless bee, using microsatellite molecular markers. We used population genetic statistics for haplodiploid organisms to address genetic structuring among male aggregations. Our findings indicate that, in general, male aggregations of T. angustula occurring over short time scales and in close proximity are genetically homogeneous as if a single aggregation. We conclude that T. angustula males randomly disperse within a population looking for mating chances rather than settle on a distinct male aggregation. This behavior seems to contribute to the reduction of inbreeding in this species.

Determination of critical nucleation number for a single nucleation amyloid-β aggregation model

Aggregates of amyloid-β (Aβ) peptide are known to be the key pathological agents in Alzheimer disease (AD). Aβ aggregates to form large, insoluble fibrils that deposit as senile plaques in AD brains. The process of aggregation is nucleation–dependent in which the formation of a nucleus is the rate–limiting step, and controls the physiochemical fate of the aggregates formed. Therefore, understanding the properties of nucleus and pre-nucleation events will be significant in reducing the existing knowledge–gap in AD pathogenesis. In this report, we have determined the plausible range of critical nucleation number (n*), the number of monomers associated within the nucleus for a homogenous aggregation model with single unique nucleation event, by two independent methods: A reduced-order stability analysis and ordinary differential equation based numerical analysis, supported by experimental biophysics. The results establish that the most likely range of n* is between 7 and 14 and within, this range, n* = 12 closely supports the experimental data. These numbers are in agreement with those previously reported, and importantly, the report establishes a new modeling framework using two independent approaches towards a convergent solution in modeling complex aggregation reactions. Our model also suggests that the formation of large protofibrils is dependent on the nature of n*, further supporting the idea that pre-nucleation events are significant in controlling the fate of larger aggregates formed. This report has re-opened an old problem with a new perspective and holds promise towards revealing the molecular events in amyloid pathologies in the future.

Shape Characteristics of Complex Single Chain and Aggregation by Exponential Law

Being an important part of polymer science, the single chain conformation and aggregation structure in polymer solution has been widely studied by many experiential exponential laws. In the review, several kinds of commonly used ex- ponential laws were summarized, and the use in the study of shape characteristics of complex single chain and aggregation was introduced. The aggregation structure and morphology of films can be controlled by precursor solution, so deep under- standing to the intrinsic properties of precursor solution is particularly important. Combined with the electron microscope, spectra, etc., the exponential law can be used to further study the single chain, aggregation size and morphology, structure evolution, and the law of the movement process of structure units at all levels in polymer solution, this will lay a theoretical foundation for the molecular designing, functional development and application of polymer materials.

Residency and Local Connectivity of White Sharks at Liguanea Island: A Second Aggregation Site in South Australia?

White sharks show a high degree of residency to specific aggregation sites, to which they return regularly over multiple years. Australian research has historically focused on single aggregation areas within each of the southern states where white sharks occur, but other key habitats likely exist and if so, will be important to identify to effectively monitor and protect threatened white shark populations. This study is the first to describe Liguanea Island as a second white shark aggregation site within South Australia, with residency periods and return visits recorded by multiple individuals. Eight sharks were detected at both Liguanea Island and the other known aggregation area in the state, the Neptune Islands, demonstrating movement between these locations. Sustained residency periods were recorded at both sites, although high periodic site fidelity was apparent with many individuals showing preference for the location at which they were tagged. Individual differences in site fidelity and residency patterns were found, although two sub-adult individuals were found to follow similar movement patterns. The implications of white shark movements, and the suggested identification of a second aggregation areas in close proximity are discussed.

A combined STM and SPA-LEED study of the “explosive” nucleation and collective diffusion in Pb/Si(111)

A novel type of very fast nucleation was recently found in Pb/Si(111) with 4- to 7-layer high islands becoming crystalline in an “explosive” way, when the Pb deposited amount in the wetting layer is compressed to θc~1.22ML, well above the metallic Pb(111) density. This “explosive” nucleation is very different from classical nucleation when island growth is more gradual and islands grow in size by single adatom aggregation [8]. In order to identify the key parameters that control the nucleation we used scanning tunneling microscopy (STM) and spot profile analysis low energy electron diffraction (SPA-LEED). It was found that the number and duration of steps in iterative deposition used to approach θc and the flux rate have dramatic effects on the crystallization process. Larger depositions over shorter times induce greater spatial coverage fluctuations, so local areas can reach the critical coverage θc easier. This can trigger the collective motion of the wetting layer from far away to build the Pb islands “explosively”. The SPA-LEED experiments show that even low flux experiments in iterative deposition experiments can trigger transfer of material to the superstable 7-layer islands, as seen from the stronger satellite rings close to the (00) spot.

Thermodynamic aspects of aurophilic hydrogelators.

The complexes [Au(4-pyridylethynyl)(phosph)] (phosph = PTA (1), DAPTA (2)) are known to produce supramolecular aggregates and gels in water. We studied the impact of these aggregation processes in the absorption spectra, (1)H NMR (at different temperatures and concentrations), and DLS and estimated the equilibrium constant for a single step aggregation of the molecule (K = 26760 and 2590 M(-1) for 1 and 2, respectively, at 25 °C). We present spectroscopic evidence for the presence of Au···Au contacts in the aggregates: the recorded changes on (1)H NMR and the appearance of new absorption bands assigned to (σ*Au···Au-π*) have been attributed to the short (Au···Au) average distances in the aggregates. Relativistic density functional theory computations support the existence of short Au···Au distances and reveal charge-transfer in the aurophilic interactions. The free energy for a single step aggregation was calculated from the experimental data, and the value obtained (ΔG ∼ -20 kJ/mol) is in good agreement with the expected values in the order of the energies found for hydrogen bonds. The DFT computations confirm the experimental findings that aggregation of monomer 1 is stronger than the aggregation of monomer 2 and the existence of aurophilic interactions.

Trapping characteristic of halloysite lumen for methyl orange

The interaction of clay minerals and dyes is an area of great interest especially in the development of novel adsorbents. In this report, we demonstrated interaction of halloysite nanotubes (HNTs) and an anionic dye, methyl orange (MO), through a electrostatic attraction. Halloysite lumen has a trapping characteristic for methyl orange, which is mainly determined by the positively charged nature of the inner surface of HNTs. XRD results confirmed that intercalation of methyl orange into HNTs did not occur. SEM–EDS and photostability results showed that MO molecules were primarily in HNTs lumen. Adsorption isotherm studies revealed an interesting phenomenon, i.e., a sudden increase of adsorption capacity occurred in the initial dye concentration of about 75mg/L, which was just the dye concentration corresponding to the onset of dye oligomer formation. This suggested dye aggregation state had a decisive influence to the adsorption behavior of MO on the halloysite. BET results demonstrated at low and high dye concentrations, single MO molecule and aggregation of several dimers through hydrophobic interaction, interacted with Al-OH2+ sites on the inner wall, respectively. Desorption experiments showed that MO in HNTs can be completely removed with deionized water, indicating halloysite is a low-cost and efficient adsorbent for anionic dye.

Performance of a Genetic Algorithm applied to robust design in multiobjective systems under different levels of fractioning

This paper studies the performance of a Genetic Algorithm (GA) to find solutions to problems of robust design in multiobjective systems with many control and noise factors, representing the output vector in a single aggregation function. The results show that the GA is able to find solutions that achieve a good adjustment of the responses to their corresponding target values and with low variability, even with highly fractional experimental designs, which provide a limited number of data points to be fed to the GA. This conclusion is important for the practical application of the GA to robust design studies. Generally, such studies are carried out using scarce resources and dealing with other limitations, which force the engineer to use few experimental treatments and gather a limited amount of data. Thus, knowing that the GA performs well under such situation expands its applicability.

Optical network scaling: roles of spectral and spatial aggregation.

As the bit rates of routed data streams exceed the throughput of single wavelength-division multiplexing channels, spectral and spatial traffic aggregation become essential for optical network scaling. These aggregation techniques reduce network routing complexity by increasing spectral efficiency to decrease the number of fibers, and by increasing switching granularity to decrease the number of switching components. Spectral aggregation yields a modest decrease in the number of fibers but a substantial decrease in the number of switching components. Spatial aggregation yields a substantial decrease in both the number of fibers and the number of switching components. To quantify routing complexity reduction, we analyze the number of multi-cast and wavelength-selective switches required in a colorless, directionless and contentionless reconfigurable optical add-drop multiplexer architecture. Traffic aggregation has two potential drawbacks: reduced routing power and increased switching component size.

Movement patterns of juvenile whale sharks tagged at an aggregation site in the Red Sea.

Conservation efforts aimed at the whale shark, Rhincodon typus, remain limited by a lack of basic information on most aspects of its ecology, including global population structure, population sizes and movement patterns. Here we report on the movements of 47 Red Sea whale sharks fitted with three types of satellite transmitting tags from 2009–2011. Most of these sharks were tagged at a single aggregation site near Al-Lith, on the central coast of the Saudi Arabian Red Sea. Individuals encountered at this site were all juveniles based on size estimates ranging from 2.5–7 m total length with a sex ratio of approximately 1∶1. All other known aggregation sites for juvenile whale sharks are dominated by males. Results from tagging efforts showed that most individuals remained in the southern Red Sea and that some sharks returned to the same location in subsequent years. Diving data were recorded by 37 tags, revealing frequent deep dives to at least 500 m and as deep as 1360 m. The unique temperature-depth profiles of the Red Sea confirmed that several whale sharks moved out of the Red Sea while tagged. The wide-ranging horizontal movements of these individuals highlight the need for multinational, cooperative efforts to conserve R. typus populations in the Red Sea and Indian Ocean.

Transaction aware tape-infrastructure monitoring

Administrating a large scale, multi protocol, hierarchical tape infrastructure like the CERN Advanced STORage manager (CASTOR)[2], which stores now 100 PB (with an increasing step of 25 PB per year), requires an adequate monitoring system for quick spotting of malfunctions, easier debugging and on demand report generation. The main challenges for such system are: to cope with CASTOR's log format diversity and its information scattered among several log files, the need for long term information archival, the strict reliability requirements and the group based GUI visualization. For this purpose, we have designed, developed and deployed a centralized system consisting of four independent layers: the Log Transfer layer for collecting log lines from all tape servers to a single aggregation server, the Data Mining layer for combining log data into transaction context, the Storage layer for archiving the resulting transactions and finally the Web UI layer for accessing the information. Having flexibility, extensibility and maintainability in mind, each layer is designed to work as a message broker for the next layer, providing a clean and generic interface while ensuring consistency, redundancy and ultimately fault tolerance. This system unifies information previously dispersed over several monitoring tools into a single user interface, using Splunk, which also allows us to provide information visualization based on access control lists (ACL). Since its deployment, it has been successfully used by CASTOR tape operators for quick overview of transactions, performance evaluation, malfunction detection and from managers for report generation.

Spatiotemporal dynamics of spawning aggregations of common snook on the east coast of Florida

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 505:227-240 (2014) - DOI: https://doi.org/10.3354/meps10774 Spatiotemporal dynamics of spawning aggregations of common snook on the east coast of Florida Joy M. Young*, Beau G. Yeiser, James A. Whittington Fish and Wildlife Research Institute, Florida Fish and Wildlife Conservation Commission Tequesta Field Laboratory, 19100 Southeast Federal Highway, Tequesta, Florida 33469, USA *Corresponding author: joy.young@myfwc.com ABSTRACT: Data collected to determine specific reproductive traits, including spatial and temporal patterns, are an area of need for improved understanding of factors that contribute to productivity in fish populations. We used passive acoustic telemetry to study the movements of 271 common snook Centropomus undecimalis on the east coast of Florida from 2008 to 2011 to assess spatial dynamics during the spawning seasons. Common snook were detected in 6 inlets from Port Canaveral to Palm Beach Inlet during the summer months when water temperature exceeded 23°C, with peak densities between July and August. Individual residency times in an aggregation were over 7.5 times shorter than the spawning season which, together with asynchronous arrival dates and frequent migrations away from the aggregation, indicates high rates of turnover. Nearly half of the tagged common snook were observed at multiple (2 to 5) spawning sites during a single season and showed varying degrees of fidelity to a spawning site. Area of residence, sex and size are influential factors in spawning traits of common snook. Females migrated earlier, made more trips, and spent longer periods in aggregations compared to males. Larger fish showed greater site fidelity to a single aggregation site. Each year a portion of the population was not detected in an inlet, implying that some common snook skip spawning or that spawning may occur outside of inlets. Findings highlight the need for a combined approach to management that includes updating the stock assessment, using more accurate measures of spawning effort and the protection of spawning areas from physical disturbance. KEY WORDS: Acoustic monitoring · Fish spawning · Fisheries management · Reproductive patterns · Centropomus undecimalis Full text in pdf format PreviousNextCite this article as: Young JM, Yeiser BG, Whittington JA (2014) Spatiotemporal dynamics of spawning aggregations of common snook on the east coast of Florida. Mar Ecol Prog Ser 505:227-240. https://doi.org/10.3354/meps10774 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 505. Online publication date: May 28, 2014 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2014 Inter-Research.