Uncoordinated access schemes for the IoT: approaches, regulations, and performance

Internet of Things (IoT) devices communicate using a variety of protocols, differing in many aspects, with the channel access method being one of the most important. Most of the transmission technologies explicitly designed for IoT and Machine-to-Machine (M2M) communication use either an ALOHA-based channel access or some type of Listen Before Talk (LBT) strategy, based on carrier sensing. In this paper, we provide a comparative overview of the uncoordinated channel access methods for IoT technologies, namely ALOHA-based and LBT schemes, in relation with the ETSI and FCC regulatory frameworks. Furthermore, we provide a performance comparison of these access schemes, both in terms of successful transmissions and energy efficiency, in a typical IoT deployment. Results show that LBT is effective in reducing inter-node interference even for long-range transmissions, though the energy efficiency can be lower than that provided by ALOHA methods. The adoption of rate-adaptation schemes, furthermore, lowers the energy consumption while improving the fairness among nodes at different distances from the receiver. Coexistence issues are also investigated, showing that in massive deployments LBT is severely affected by the presence of ALOHA devices in the same area

Why Now?: A Case Study of Split Estate and Fracking Activity in Garfield County Colorado

This research examines the socio-environmental impacts associated with hydraulic fracturing activities and issues of split estate in Battlement Mesa Planned Unit Development in Garfield County, CO. Data for this research was collected during 2 months in the summer of 2015 using a series of ethnographic research methods. In doing so, this research adopts political ecology and political economy of nature as theoretical frameworks to understand the interconnections that exist between local impacts of fracking activities and a national strategy to secure gas markets internationally. I argue that the socio-environmental impacts associated with hydraulic fracturing in Garfield County, CO are not only the result of issues related to split estate, but are also the result of a national strategy lead by the federal government to create a supranational trade agreement known as the Trans Pacific Partnership (TPP) that incentivizes U.S. natural gas exports, which in-turn will maximize profits generated from those exports at a national scale

Platforms and Protocols for the Internet of Things

Building a general architecture for the Internet of Things (IoT) is a very complex task, exacerbated by the extremely large variety of devices, link layer technologies, and services that may be involved in such a system. In this paper, we identify the main blocks of a generic IoT architecture, describing their features and requirements, and analyze the most common approaches proposed in the literature for each block. In particular, we compare three of the most important communication technologies for IoT purposes, i.e., REST, MQTT, and AMQP, and we also analyze three IoT platforms: openHAB, Sentilo, and Parse. The analysis will prove the importance of adopting an integrated approach that jointly addresses several issues and is able to flexibly accommodate the requirements of the various elements of the system. We also discuss a use case which illustrates the design challenges and the choices to make when selecting which protocols and technologies to use

Tuning the aspect ratio of arrays of silica nanochannels

Arrays of silica nanochannels (ASNCs) are ordered mesoporous silica particles with hexagonal prismatic shape. The entrances of the well-defined one-dimensional nanochannels are located on the base surfaces of the hexagonal prisms. The aspect ratio of the micrometer-sized particles (length-to-diameter ratio) can be tuned in the range of 0.8 to 2.2 by the addition of co-ions (K+ and Ca2+) to the hexadecyltrimethylammonium bromide (CTAB) templated synthesis and by an adjustment of the relative amounts of silica precursor (tetraethoxysilane) and CTAB. The length of the nanochannels can be varied between 2 and 9 μm. Co-ions thereby not only improve the regularity of the hexagonal prismatic particle shape, but also affect the diameter of the nanochannels, which lies at approximately 2.6 nm (with K+ as co-ion) and 3.2 nm (with Ca2+ as co-ion)

Functionalization of arrays of silica nanochannels by post-condensation

Functionalized arrays of silica nanochannels (ASNCs) were prepared by post-condensation of amino-functional alkoxysilanes (NH-silanes). The method of post-condensation combines postsynthetic grafting and co-condensation – the classical pathways for the functionalization of mesoporous silica – to afford a convenient one-pot reaction in aqueous medium. The structure of the NH-silanes determines the distribution of the surface-bound groups in the ASNCs. Accumulation at the channel entrances was observed by confocal laser scanning microscopy in the case of sterically hindered NH-silanes, whereas smaller NH-silanes led to a more uniform distribution. In all cases, the channels remained accessible for additional postsynthetic treatment or introduction of guests after extraction of the structure-directing agent. The particle size and morphology, as well as the pore size and the degree of ordering of the amino-functionalized ASNCs were comparable to pristine ASNCs

Massgeschneiderte Nanokanäle

https://www.zhaw.ch/de/lsfm/forschung/projekte-und-publikationen/transfer

Indigo in the nanochannels of zeolite L : towards a new type of colorant

A host-guest based colorant was synthesized by intercalating indigo molecules into the nanochannels of zeolite L (ZL). Reductive washing thereby ensured the efficient and selective removal of non-intercalated indigo molecules. The UV-vis diffuse reflectance spectrum of the product after intercalation and reductive washing (designated as indigo-ZL) was found to resemble the solution spectrum of indigo, leading to the conclusion that the formation of indigo aggregates is prevented due to the steric constraints imposed by the microporous structure of ZL. The application of indigo-ZL on cotton was tested by roll coating. The light absorption properties of the resulting textile prints showed no significant alteration when compared to the pure indigo-ZL powder. The UV-vis diffuse reflectance spectra of mixtures consisting of indigo-ZL and a further ZL-based colorant were successfully predicted by the weighted addition of the respective primary spectra

THE IMPACT OF THE WIDESPREAD SCREENING THROUGH PROSTATE-SPECIFIC ANTIGEN (PSA) TEST ON POPULATION-BASED MODELS FOR ESTIMATING PROSTATE CANCER BURDEN

Introduction. Screening for prostate cancer (PCa) through Prostate-Specific Antigen (PSA) test widespread in high-income countries long before definitive results about its efficacy. Actually, even though PSA testing do contribute to reduce PCa mortality, the harm to benefit ratio remains controversial, given that PSA testing can detect cancers that may otherwise go undiagnosed during a man\u2019s life (i.e., overdiagnosis and, consequently, overtreatment with severe side effects). To evaluate the impact of PSA testing diffusion in the Friuli Venezia Giulia (FVG) region, population-based methods for estimating and projecting cancer morbidity and mortality indicators were applied to PCa and results were compared to observed data. Taking advantage of the complete coverage of the FVG population of both the regional cancer registry and the digital health archive, data on PCa cases and on PSA testing use were concurrently analyzed. Estimates of prostate cancer burden in Friuli Venezia Giulia. Methods. The Mortality and Incidence Analysis Model (MIAMOD) (Verdecchia, 1989) is a regression of mortality on observed mortality data (from official statistics) to back-calculate age-period-cohort incidence. The MIAMOD method was applied for estimating and projecting incidence, mortality, and prevalence for selected cancers in FVG region in the period 1970-2015 (Zucchetto et al, 2013). For PCa, a specific procedure was used to better capture recent variations: preliminary mortality estimation up to 2010 was performed using regional mortality data for the period 1970-2007; relative survival estimates were calculated using data from EUROCARE-4 in the period 1985-2002 and modeled by means of mixture cure models of the Weibull type with power function at macro-area level (North-East) for the period 2003-2005, and then assumed to be constant. Results. MIAMOD estimates showed a high goodness of fit with the observed incidence for all cancer sites, except for PCa. Although both increasing with time, PCa incidence rates estimates were much lower than observed incidence rates, especially in the period 1996-2007 and they seemed to converge in 2008-2009. Conversely, in the same period, mortality rates were almost stable. Analysis of PSA testing rates and PCa incidence rates trends in Friuli Venezia Giulia. Methods. Data on PSA tests performed in men aged 40+ years were retrieved from FVG digital health archive for the period 1998-2012. The overall PSA testing rates were calculated as the number of tested men each year (multiple prescriptions to the same man were counted once) over the male population. PCa incidence rates (from the FVG cancer registry) among men aged 40+ years or more were analyzed for the period 1995-2009. Joinpoint regression analysis was performed to identify knots where a statistically significant change over time in the log-slope of the rates occurred. Age-period-cohort analyses were also performed. In order to solve the unidentifiability problem, the following assumptions have been made (based on preliminary plots of rates by periods, birth cohorts, and age classes): a period was selected as reference; cohort effects were constrained to be 0 on average with 0 slope. Age effects represented age-specific rates in the reference period, after adjustment for the cohort effects; period effects were interpretable as rate ratios (RRs) relative to the reference period; cohort effects were interpretable as residual RRs relative to the age-period prediction. Results. PSA testing increased from 12,792 per 100,000 men in 1998, up to 30,407 in 2009, and then slightly decreased. Significant changes emerged in 2002 and 2008, with a high increase of rates in the period 1998-2002 (annual percent change, aPC=16.9; 95% confidence interval, CI: 12.9 to 21.2), a smaller increase in the period 2002-2008 (aPC=3.6; 95% CI: 1.7 to 5.5), and a subsequent stabilization (aPC= -0.7; 95% CI: -3.1 to 1.8). Similar patterns emerged by age strata. Compared to reference period 1998-2002, PSA testing rates were significantly higher in 2003-2007 and stabilized thereafter. Age effects indicated sharp increasing rates up to age 70-74 years and then a reduction. No particular cohort effects emerged, except for a tendency of more recently born men to undergo PSA testing. Age-drift was equal to 4.7% (95% CI: 4.7% to 4.7%). The overall crude incidence rate of PCa increased from 219.8 per 100,000 men in 1995, up to 385.5 in 2007, and then decreased down to 328.3 in 2009. Joinpoint analysis estimated statistically significant changes in PCa incidence rates log-slopes in 1998 and 2007: the aPCs in the periods 1995-1998, 1998-2007, and 2007-2009 were 12.1 (95% CI: 6.6 to 17.9), 1.9 (95% CI: 0.9 to 2.8), and -7.0 (95% CI: -14.3 to 0.9), respectively. The results of age-period-cohort analysis with natural splines showed, as compared to the reference period 1995-1999, higher incidence rates in the subsequent 5-year period and then a plateau (the analysis performed using 1-year time spans, highlighted an increase up to 2007 followed by a reduction). Age-specific PCa incidence rates were sharply increasing up to 70-75 years and then reduced. Residual cohort effects highlighted high increasing risks for the most recently born men (i.e., after 1950). The age-drift was equal to 2.3% (95% CI: 1.9%-2.7%). Discussion. The diffusion of PSA testing in FVG has inflated the incidence of PCa without affecting the overall mortality. Given that MIAMOD estimates are based on mortality data, which have not been so heavily modified by the introduction of PSA test as PCa incidence rates, this could explain the difference between MIAMOD estimates and observed incidence rates, especially in the period 1996-2007. Though the period was not totally coincident, trend over time of PCa incidence rates resembled to some extent those of PSA-testing rates and the age, period, and cohort effects were somewhat similar (though PCa incidence was more affected by cohort effects). The PCa incidence estimates produced using MIAMOD could be considered as the rates that would be observed in FVG in the absence of such a great increase of PSA testing use (observed since 1998, but reasonably started before). Therefore, the difference between observed and estimated incidence rates (ranging between 7% and 18% in the period 1996-2007, median 11%), could be attributable to screening with PSA and, reasonably, to overdiagnosis. These results are in line with estimates of overdiagnosis derived from micro-simulation models based on randomized trials results. Conclusion. Estimates of PCa incidence and prevalence based on mortality data should be carefully evaluated taking into account of the age, period, and cohort trends of PSA testing data, which are available in several areas, including those not yet covered by cancer registration

Solutions for large scale, efficient, and secure Internet of Things

The design of a general architecture for the Internet of Things (IoT) is a complex task, due to the heterogeneity of devices, communication technologies, and applications that are part of such systems. Therefore, there are significant opportunities to improve the state of the art, whether to better the performance of the system, or to solve actual issues in current systems. This thesis focuses, in particular, on three aspects of the IoT. First, issues of cyber-physical systems are analysed. In these systems, IoT technologies are widely used to monitor, control, and act on physical entities. One of the most important issue in these scenarios are related to the communication layer, which must be characterized by high reliability, low latency, and high energy efficiency. Some solutions for the channel access scheme of such systems are proposed, each tailored to different specific scenarios. These solutions, which exploit the capabilities of state of the art radio transceivers, prove effective in improving the performance of the considered systems. Positioning services for cyber-physical systems are also investigated, in order to improve the accuracy of such services. Next, the focus moves to network and service optimization for traffic intensive applications, such as video streaming. This type of traffic is common amongst non-constrained devices, like smartphones and augmented/virtual reality headsets, which form an integral part of the IoT ecosystem. The proposed solutions are able to increase the video Quality of Experience while wasting less bandwidth than state of the art strategies. Finally, the security of IoT systems is investigated. While often overlooked, this aspect is fundamental to enable the ubiquitous deployment of IoT. Therefore, security issues of commonly used IoT protocols are presented, together with a proposal for an authentication mechanism based on physical channel features. This authentication strategy proved to be effective as a standalone mechanism or as an additional security layer to improve the security level of legacy systems