A framework for interference analysis of heterogeneous radio networks

The increasing use of unlicensed frequency bands for radio communications calls for investigations of the interference between coexisting radio networks. The wide variety of radio interfaces makes such investigations hard to perform. In this paper we present a general framework for the analysis of heterogeneous interfering radio networks, where the networks are modeled with individual properties for the packet types used, transmitted power distributions in time and frequency from the packet transmissions, and with path loss between network nodes. By using closed form expressions for the throughput of the networks, important mechanisms limiting their performance can be investigated. The closed form expressions enable fast and flexible analysis to be performed without extensive computer simulations. To illustrate the use of the framework we analyze an example system of interfering IEEE 802.11b and Bluetooth network

Energy-based throughput analysis of packet radio networks

The increasing use of wireless technology utilizing unlicensed frequency bands calls for more in-depth analysis of interference and coexistence between systems. In this paper a framework is presented for detailed analysis of the performance of coexisting networks in shared frequency bands. The framework allows for multiple packet lengths to be used by the communicating devices and the analysis is performed with respect to the received interfering energy, which in effect leads to a link budget analysis on a packet basis. A system of interfering Bluetooth piconets is analyzed to illustrate the use of the framework and the conceptual difference in basing the analysis on link budgets, rather than on packet collisions. Furthermore, some indications on throughput saturation in the analyzed Bluetooth system are presented

Species composition and abundance of entomopathogenic Metarhizium fungi in soils of a forest, pasture and agricultural field in Sweden

Annually insect and arthropod pests cause damage to both crops and cattle. In recent decades there has been an increased attention towards using alternative methods for pest control. The genus Metarhizium contains several soil associated entomopathogenic species of fungi which may be used as effective solutions for biological control of invertebrate pests. However, while the pathogenicity has been thoroughly studied, the ecology of this fungal group remains a tentative mystery. The aims of this study were to study the natural abundance of Metarhizium in a forest, pasture and agricultural field in Sweden. Out of 36 soil samples two species, Metarhizium flavoviride var. pemphigi and Metarhizium guizhouense were isolated from forest soil. A cultivation-independent assay revealed that the agricultural field harbored the highest abundance of Metarhizium. These findings are most likely due to the effect of local weather conditions at the time of sampling. The results herein indicates that time of sampling is a more important factor than previously anticipated

Throughput analysis of strongly interfering slow frequency-hopping wireless networks

We derive an approximation for the throughput of strongly interfering frequency-hopping wireless networks, where packet collisions always result in lost data. A system is defined to consist of a certain number of radio networks, each with an arbitrary number of communicating units, coordinated to communicate without interference. Using the approximation, we estimate upper and lower bounds on system throughput, as well as the number of networks which gives maximum system throughpu

Analysis and modeling of hydrothermal plume data acquired from the 85°E segment of the Gakkel Ridge

Author Posting. © American Geophysical Union, 2010. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 115 (2010): C06028, doi:10.1029/2009JC005776.We use data from a CTD plume-mapping campaign conducted during the Arctic Gakkel Vents (AGAVE) expedition in 2007 to constrain the nature of hydrothermal processes on the Gakkel Ridge at 85°E. Thermal and redox potential (Eh) anomalies were detected in two discrete depth intervals: 2400–2800 m (Interval 1) and 3000–3800 m (Interval 2). The spatial and temporal patterns of the signals indicate that the Interval 1 anomalies were most likely generated by a single large, high-temperature (T > 100°C) vent field located on the fault terraces that form the NE axial valley wall. In contrast, the Interval 2 anomalies appear to have been generated by up to 7 spatially distinct vent fields associated with constructional volcanic features on the floor of the axial valley, many of which may be sites of diffuse, low-temperature (T < 10°C) discharge. Numerical simulations of turbulent plumes rising in a weakly stratified Arctic Ocean water column indicate that the high-temperature field on the axial valley wall has a thermal power of ∼1.8 GW, similar to the Trans-Atlantic Geotraverse and Rainbow fields in the Atlantic Ocean, whereas the sites on the axial valley floor have values ranging from 5 to 110 MW.Thiswork was funded by the NSF Office of Polar Programs, Tellus—The Centre of Earth Systems Science at theUniversity of Gothenburg, and the Woods Hole Oceanographic Institution

Dynamic simulations of potential methane release from East Siberian continental slope sediments

Sediments deposited along continental margins of the Arctic Ocean presumably host large amounts of methane (CH4) in gas hydrates. Here we apply numerical simulations to assess the potential of gas hydrate dissociation and methane release from the East Siberian slope over the next 100 years. Simulations are based on a hypothesized bottom water warming of 3°C, and an assumed starting distribution of gas hydrate. The simulation results show that gas hydrate dissociation in these sediments is relatively slow, and that CH4 fluxes toward the seafloor are limited by low sediment permeability. The latter is true even when sediment fractures are permitted to form in response to overpressure in pore space. With an initial gas hydrate distribution dictated by present-day pressure and temperature conditions, nominally 0.35 Gt of CH4 are released from the East Siberian slope during the first 100 years of the simulation. However, this CH4 discharge becomes significantly smaller (~0.05 Gt) if glacial sea level changes in the Arctic Ocean are considered. This is because a lower sea level during the last glacial maximum (LGM) must result in depleted gas hydrate abundance within the most sensitive region of the modern gas hydrate stability zone. Even if all released CH4 reached the atmosphere, the amount coming from East Siberian slopes would be trivial compared to present-day atmospheric CH4 inputs from other sources

Intrusive thoughts and quality of life among men with prostate cancer before and three months after surgery.

To access publisher's full text version of this article, please click on the hyperlink in Additional Links field or click on the hyperlink at the top of the page marked Files. This article is open access.Sudden, unwelcome and repetitive thoughts about a traumatic event--intrusive thoughts--could relate to how men assess their quality of life after prostate-cancer diagnosis. We aimed to study the prevalence of intrusive thoughts about prostate cancer and their association with quality-of-life outcomes before and after radical prostatectomy.During the first year of the LAPPRO-trial, 971 men scheduled for radical prostatectomy were prospectively included from 14 urological centers in Sweden. Of those, 833 men responded to two consecutive study-specific questionnaires before and three months after surgery (participation rate 86%). The association of intrusive thoughts with three quality-of-life outcomes, i.e. self-assessed quality of life, depressive mood and waking up with anxiety was estimated by prevalence ratios that were calculated, together with a 95% confidence interval, at the same time-point as well as over time. Fisher's exact-test was used to analyze differences between respondents and non-respondents. Wilcoxon signed-ranks and Cochran-Armitage trend tests were used for analysis of change over time. To validate new questions on intrusive thoughts, written answers to open-ended questions were read and analyzed by qualitative content analysis.Before surgery, 603 men (73%) reported negative intrusive thoughts about their cancer at some time in the past month and 593 men (59%) reported such thoughts three months after surgery. Comparing those reporting intrusive thoughts at least weekly or once a week before surgery with those who did not, the prevalence ratio (95% confidence interval), three months after surgery, for waking up in the middle of the night with anxiety was 3.9 (2.7 to 5.5), for depressed mood 1.8 (1.6 to 2.1) and for impaired self-assessed quality of life 1.3 (1.2 to 1.5).The prevalence of negative intrusive thoughts about prostate cancer at the time of surgery associates with studied quality-of-life outcomes three months later.Current Controlled Trials, ISRCTN06393679.Swedish Cancer Society CAN2008/922 CAN2009/1099 CAN2010/593 Region Vastra Gotaland Sahlgrenska University Hospital VGR 27551 79291 152231 ALF 11573 138751 146201 HTA - VGR 6011 Swedish Research Council Mrs Mary von Sydow Foundation Anna and Edvin Berger foundat

Observations and modeling of a hydrothermal plume in Yellowstone Lake

Author Posting. © American Geophysical Union, 20XX. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 46(12), (2019): 6435-6442, doi:10.1029/2019GL082523.Acoustic Doppler current profiler and conductivity‐temperature‐depth data acquired in Yellowstone Lake reveal the presence of a buoyant plume above the “Deep Hole” hydrothermal system, located southeast of Stevenson Island. Distributed venting in the ~200 × 200‐m hydrothermal field creates a plume with vertical velocities of ~10 cm/s in the mid‐water column. Salinity profiles indicate that during the period of strong summer stratification the plume rises to a neutral buoyancy horizon at ~45‐m depth, corresponding to a ~70‐m rise height, where it generates an anomaly of ~5% (−0.0014 psu) relative to background lake water. We simulate the plume with a numerical model and find that a heat flux of 28 MW reproduces the salinity and vertical velocity observations, corresponding to a mass flux of 1.4 × 103 kg/s. When observational uncertainties are considered, the heat flux could range between 20 to 50 MW.The authors thank Yellowstone National Park Fisheries and Aquatic Sciences, The Global Foundation for Ocean Exploration, and Paul Fucile for logistical support. This research was supported by the National Science Foundation grants EAR‐1516361 to R. S., EAR‐1514865 to K. L., and EAR‐1515283 to R. H. and J. F. All work in Yellowstone National Park was completed under an authorized Yellowstone research permit (YELL‐2018‐SCI‐7018). CTD and ADCP profiles reported in this paper are available through the Marine Geoscience Data System (doi:10.1594/IEDA/324713 and doi:10.1594/IEDA/324712, accessed last on 17 April 2019, respectively).2019-11-0