Cluster based jamming and countermeasures for wireless sensor network MAC protocols

A wireless sensor network (WSN) is a collection of wireless nodes, usually with limited computing resources and available energy. The medium access control layer (MAC layer) directly guides the radio hardware and manages access to the radio spectrum in controlled way. A top priority for a WSN MAC protocol is to conserve energy, however tailoring the algorithm for this purpose can create or expose a number of security vulnerabilities. In particular, a regular duty cycle makes a node vulnerable to periodic jamming attacks. This vulnerability limits the use of use of a WSN in applications requiring high levels of security. We present a new WSN MAC protocol, RSMAC (Random Sleep MAC) that is designed to provide resistance to periodic jamming attacks while maintaining elements that are essential to WSN functionality. CPU, memory and especially radio usage are kept to a minimum to conserve energy while maintaining an acceptable level of network performance so that applications can be run transparently on top of the secure MAC layer. We use a coordinated yet pseudo-random duty cycle that is loosely synchronized across the entire network via a distributed algorithm. This thwarts an attacker\u27s ability to predict when nodes will be awake and likewise thwarts energy efficient intelligent jamming attacks by reducing their effectiveness and energy-efficiency to that of non-intelligent attacks. Implementing the random duty cycle requires additional energy usage, but also offers an opportunity to reduce asymmetric energy use and eliminate energy use lost to explicit neighbor discovery. We perform testing of RSMAC against non-secure protocols in a novel simulator that we designed to make prototyping new WSN algorithms efficient, informative and consistent. First we perform tests of the existing SMAC protocol to demonstrate the relevance of the novel simulation for estimating energy usage, data transmission rates, MAC timing and other relevant macro characteristics of wireless sensor networks. Second, we use the simulation to perform detailed testing of RSMAC that demonstrates its performance characteristics with different configurations and its effectiveness in confounding intelligent jammers

THE USE OF DISCRETE VARIABLES TO ESTIMATE PRICE AND INCOME ELASTICITIES FOR PRODUCTS WITH SEASONAL CONSUMPTION PATTERNS

Food Consumption/Nutrition/Food Safety,

Landscape Loopholes: Moments for Change

Social-ecological systems are breaking down at local, regional, and global scales, and sustainability seems an increasingly distant aspiration. Social harmony and economic systems are connected to ecological systems and climate, in multiple complex ways, at many scales. Adapting research practice to match integration opportunities within social-ecological systems could contribute foresight capabilities emerging from landscape change studies, which can be coupled with emerging policy transformation opportunities. The shaping of landscapes by human imagination and physical action creates meaningful contexts for building sustainability. However, the policy landscape is often dominated by circularity and “lock-in” to unsustainable pathways that are hard to escape. Moments for change emerge through timely convergence of circumstances, within a landscape context, that provide a window of opportunity—a “landscape loophole”—through which the transformation to more sustainable social-ecological relationships might be achieved. Creating future options redundancy (FOR) plans, a variety of possible pathways and alternative landscape futures within the characteristics and capacity of a region, could facilitate policy shifts and adaptive capacity, and reduce risk through reflexive future options. The convergence of circumstances providing loophole opportunities to escape existing lock-in might be understood, and even predicted, by closely coupling landscape sciences and policy research

An Alternative Futures Approach to Green Infrastructure Planning for an Increasing Population

In 2017, the U.S. Census Bureau announced Idaho to be the fastest growing state by population in the country. As these trends continue, this growth can have various impacts on socio-ecological systems such as increased development, pressure exerted on agricultural production, and increased effects of urban stream syndrome. Various scenarios, driven by stakeholders, can help effectively guide the designs of our green infrastructure networks. This project evokes stakeholder-defined key issues addressed within a National Science Foundation (NSF) funded project in Idaho’s Magic Valley. Innovations at the Nexus of Food, Energy, and Water Systems (INFEWS) is an interdisciplinary research initiative seeking to address issues concerning drought, water demand, water quality, and food security by using a stakeholder-driven alternative futures framework (Steinitz 2012). Researchers within the project seek to operationalize stakeholder-driven assumptions for various scenarios utilizing the planning and suitability of effective Best Management Practices (BMPs) for the Magic Valley in Idaho. The project will utilize an alternative futures methodology to interpret and represent rural and urban green infrastructure interventions at various locations within the watershed. This approach has the potential to operate at various scales and, through this project, we seek to construct the narrative at both the landscape and the site scale. The results aim to provide policy makers, planners, developers, and landscape architects about siting various BMP types through a framework for planning and design. These outputs will also depict modeled landscape change via various scenario solutions. The stakeholder group will substantiate plausible solutions and scenarios for the Valley, which will guide the green infrastructure network. Once validated, we will focus on the siting of three different structural BMP networks to address water quality, water quantity, soil health, and inclusion of public green space

High-resolution spectroscopy of QY Sge -- An obscured RV Tauri variable?

The first high-resolution optical spectra of QY Sge are presented and discussed. Menzies & Whitelock (1988) on the basis of photometry and low-resolution spectra suggested that this G0I supergiant was obscured by dust and seen only by scattered light from a circumstellar reflection nebula. The new spectra confirm and extend this picture. Photospheric lines are unusually broad indicating scattering of photons from dust in the stellar wind. Presence of very broad Na D emission lines is confirmed. Sharp emission lines from low levels of abundant neutral metal atoms are reported for the first time. An abundance analysis of photospheric lines shows that the stellar atmosphere is of approximately solar composition but with highly condensible (e.g., Sc and Ti) elements depleted by factors of 5 to 10.Comment: 8 pages, 9 figures, accepted for publication in MNRA

Acceleration of small intestine development and remodeling of the microbiome following hyaluronan 35 KDa treatment in neonatal mice

The beneficial effects of human milk suppressing the development of intestinal pathologies such as necrotizing enterocolitis in preterm infants are widely known. Human milk (HM) is rich in a multitude of bioactive factors that play major roles in promoting postnatal maturation, differentiation, and the development of the microbiome. Previous studies showed that HM is rich in hyaluronan (HA) especially in colostrum and early milk. This study aims to determine the role of HA 35 KDa, a HM HA mimic, on intestinal proliferation, differentiation, and the development of the intestinal microbiome. We show that oral HA 35 KDa supplementation for 7 days in mouse pups leads to increased villus length and crypt depth, and increased goblet and Paneth cells, compared to controls. We also show that HA 35 KDa leads to an increased predominance of Clostridiales Ruminococcaceae, Lactobacillales Lactobacillaceae, and Clostridiales Lachnospiraceae. In seeking the mechanisms involved in the changes, bulk RNA seq was performed on samples from the terminal ileum and identified upregulation in several genes essential for cellular growth, proliferation, and survival. Taken together, this study shows that HA 35 KDa supplemented to mouse pups promotes intestinal epithelial cell proliferation, as well as the development of Paneth cells and goblet cell subsets. HA 35 KDa also impacted the intestinal microbiota; the implications of these responses need to be determined

Photometric redshifts and quasar probabilities from a single, data-driven generative model

We describe a technique for simultaneously classifying and estimating the redshift of quasars. It can separate quasars from stars in arbitrary redshift ranges, estimate full posterior distribution functions for the redshift, and naturally incorporate flux uncertainties, missing data, and multi-wavelength photometry. We build models of quasars in flux-redshift space by applying the extreme deconvolution technique to estimate the underlying density. By integrating this density over redshift one can obtain quasar flux-densities in different redshift ranges. This approach allows for efficient, consistent, and fast classification and photometric redshift estimation. This is achieved by combining the speed obtained by choosing simple analytical forms as the basis of our density model with the flexibility of non-parametric models through the use of many simple components with many parameters. We show that this technique is competitive with the best photometric quasar classification techniques---which are limited to fixed, broad redshift ranges and high signal-to-noise ratio data---and with the best photometric redshift techniques when applied to broadband optical data. We demonstrate that the inclusion of UV and NIR data significantly improves photometric quasar--star separation and essentially resolves all of the redshift degeneracies for quasars inherent to the ugriz filter system, even when included data have a low signal-to-noise ratio. For quasars spectroscopically confirmed by the SDSS 84 and 97 percent of the objects with GALEX UV and UKIDSS NIR data have photometric redshifts within 0.1 and 0.3, respectively, of the spectroscopic redshift; this amounts to about a factor of three improvement over ugriz-only photometric redshifts. Our code to calculate quasar probabilities and redshift probability distributions is publicly available

Shining Light on Merging Galaxies I: The Ongoing Merger of a Quasar with a `Green Valley' Galaxy

Serendipitous observations of a pair z = 0.37 interacting galaxies (one hosting a quasar) show a massive gaseous bridge of material connecting the two objects. This bridge is photoionized by the quasar (QSO) revealing gas along the entire projected 38 kpc sightline connecting the two galaxies. The emission lines that result give an unprecedented opportunity to study the merger process at this redshift. We determine the kinematics, ionization parameter (log U ~ -2.5 +- 0.03), column density (N_H ~ 10^{21} cm^{-2}), metallicity ([M/H] ~ -0.20 +- 0.15), and mass (~ 10^8 Msun) of the gaseous bridge. We simultaneously constrain properties of the QSO-host (M_DM>8.8x 10^{11} Msun) and its companion galaxy (M_DM>2.1 x 10^{11} Msun; M_star ~ 2 x 10^{10} Msun; stellar burst age=300-800 Myr; SFR~6 Msun/yr; and metallicity 12+log (O/H)= 8.64 +- 0.2). The general properties of this system match the standard paradigm of a galaxy-galaxy merger caught between first and second passage while one of the galaxies hosts an active quasar. The companion galaxy lies in the so-called `green valley', with a stellar population consistent with a recent starburst triggered during the first passage of the merger and has no detectable AGN activity. In addition to providing case-studies of quasars associated with galaxy mergers, quasar/galaxy pairs with QSO-photoionized tidal bridges such as this one offer unique insights into the galaxy properties while also distinguishing an important and inadequately understood phase of galaxy evolution.Comment: 23 pages, 12 figures, 5 tables, Submitted to ApJ, revised to address referee's comment

On the mechanism of ubiquinone mediated photocurrent generation by a reaction center based photocathode

Upon photoexcitation, the reaction center (RC) pigment-proteins that facilitate natural photosynthesis achieve a metastable separation of electrical charge among the embedded cofactors. Because of the high quantum efficiency of this process, there is a growing interest in their incorporation into biohybrid materials for solar energy conversion, bioelectronics and biosensing. Multiple bioelectrochemical studies have shown that reaction centers from various photosynthetic organisms can be interfaced with diverse electrode materials for the generation of photocurrents, but many mechanistic aspects of native protein functionality in a non-native environment is unknown. In vivo, RC's catalyse ubiquinone-10 reduction, protonation and exchange with other lipid phase ubiquinone-10s via protein-controlled spatial orientation and protein rearrangement. In contrast, the mechanism of ubiquinone-0 reduction, used to facilitate fast RC turnover in an aqueous photoelectrochemical cell (PEC), may not proceed via the same pathway as the native cofactor. In this report we show truncation of the native isoprene tail results in larger RC turnover rates in a PEC despite the removal of the tail's purported role of ubiquinone headgroup orientation and binding. Through the use of reaction centers with single or double mutations, we also show the extent to which two-electron/two-proton ubiquinone chemistry that operates in vivo also underpins the ubiquinone-0 reduction by surface-adsorbed RCs in a PEC. This reveals that only the ubiquinone headgroup is critical to the fast turnover of the RC in a PEC and provides insight into design principles for the development of new biophotovoltaic cells and biosensors

A High Yield of New Sightlines for the Study of Intergalactic Helium: Far-UV-Bright Quasars from SDSS, GALEX, and HST

Investigations of He II Ly-alpha (304 A rest) absorption toward a half-dozen quasars at z~3-4 have demonstrated the great potential of helium studies of the IGM, but the current critically small sample size of clean sightlines for the He II Gunn-Peterson test limits confidence in cosmological inferences, and a larger sample is required. Although the unobscured quasar sightlines to high redshift are extremely rare, SDSS DR6 provides thousands of z>2.8 quasars. We have cross-correlated these SDSS quasars with GALEX GR2/GR3 to establish a catalog of 200 higher-confidence (~70% secure) cases of quasars at z=2.8-5.1 potentially having surviving far-UV (restframe) flux. We also catalog another 112 likely far-UV-bright quasars from GALEX cross-correlation with other (non-SDSS) quasar compilations. Reconnaissance UV prism observations with HST of 24 of our SDSS/GALEX candidates confirm 12 as detected in the far-UV, with at least 9 having flux extending to very near the He II break; with refinements our success rate is even higher. Our SDSS/GALEX selection approach is thereby confirmed to be an order of magnitude more efficient than previous He II quasar searches, more than doubles the number of spectroscopically confirmed clean sightlines to high redshift, and provides a resource list of hundreds of high-confidence sightlines for upcoming He II and other far-UV studies from HST. Our reconnaissance HST prism spectra suggest some far-UV diversity, confirming the need to obtain a large sample of independent quasar sightlines across a broad redshift range to assess such issues as the epoch(s) of helium reionization, while averaging over individual-object pathology and/or cosmic variance.Comment: 32 pages, 7 figures, accepted by Ap