Edge usage, motifs and regulatory logic for cell cycling genetic networks

The cell cycle is a tightly controlled process, yet its underlying genetic network shows marked differences across species. Which of the associated structural features follow solely from the ability to impose the appropriate gene expression patterns? We tackle this question in silico by examining the ensemble of all regulatory networks which satisfy the constraint of producing a given sequence of gene expressions. We focus on three cell cycle profiles coming from baker's yeast, fission yeast and mammals. First, we show that the networks in each of the ensembles use just a few interactions that are repeatedly reused as building blocks. Second, we find an enrichment in network motifs that is similar in the two yeast cell cycle systems investigated. These motifs do not have autonomous functions, but nevertheless they reveal a regulatory logic for cell cycling based on a feed-forward cascade of activating interactions.Comment: 9 pages, 9 figures, to be published in Phys. Rev.

The Feasibility of Counting Songbirds Using Unmanned Aerial Vehicles

Obtaining unbiased survey data for vocal bird species is inherently challenging due to observer biases, habitat coverage biases, and logistical constraints. We propose that combining bioacoustic monitoring with unmanned aerial vehicle (UAV) technology could reduce some of these biases and allow bird surveys to be conducted in less accessible areas. We tested the feasibility of the UAV approach to songbird surveys using a low-cost quadcopter with a simple, lightweight recorder suspended 8 m below the vehicle. In a field experiment using playback of bird recordings, we found that small variations in UAV altitude (it hovered at 28, 48, and 68 m) didn\u27t have a significant effect on detections by the recorder attached to the UAV, and we found that the detection radius of our equipment was comparable with detection radii of standard point counts. We then field tested our equipment, comparing songbird detections from our UAV-mounted recorder with standard point-count data from 51 count stations. We found that the number of birds per point on UAV counts was comparable with standard counts for most species, but there were significant underestimates for some—specifically, issues of song masking for a species with a low-frequency song, the Mourning Dove (Zenaida macroura); and underestimation of the abundance of a species that was found in very high densities, the Gray Catbird (Dumetella carolinensis). Species richness was lower on UAV counts (mean = 5.6 species point−1) than on standard counts (8.3 species point−1), but only slightly lower than on standard counts if nonaudible detections are omitted (6.5 species point−1). Excessive UAV noise is a major hurdle to using UAVs for bioacoustic monitoring, but we are optimistic that technological innovations to reduce motor and rotor noise will significantly reduce this issue. We conclude that UAV-based bioacoustic monitoring holds great promise, and we urge other researchers to consider further experimentation to refine techniques

Online Mapping Tools for Geolocating Amish Settlements

This technical note demonstrates the value of using online mapping tools as a method of geolocating Amish settlements. Primarily using freely available Bing and Google maps and published lists of the addresses of Amish ministers, we geolocated 1,362 Amish households in Ohio and 1,203 in Pennsylvania, representing about 10% of Amish households in those states. From these data we were able to derive a population density map of the Amish across Ohio and Pennsylvania. We caution that our map is merely a model and based on several assumptions, but the product is a finer resolution map of Amish distribution than has previously been published. We add that the locations of Amish schools provide another promising avenue for geolocation of Amish settlements, but we were not able to locate sufficiently comprehensive lists to include them in our analysis

The Feasibility of Using Drones to Count Songbirds

Point and transect counts are the most common bird survey methods, but are subject to biases and accessibility issues. To eliminate some of these biases, we propose attaching a recorder to a consumer-grade quadcopter (Unmanned Aerial Vehicle, or UAV) to estimate songbird populations from audio recordings. We conducted a blind experiment using broadcast recordings to estimate the detection radius of a compact recorder attached to a UAV, and found that the detection radius did not vary significantly when the UAV was flown at elevations of 20, 40 and 60m. We field tested our system by comparing UAV-based bird counts with standard point count surveys at 51 locations on State Game Lands 249, PA. Species richness was similar at standard and UAV point counts, but species composition differed. For most species, the number detections on UAV recordings were similar to standard counts, but UAV surveys under-sampled Mourning Doves Zenaida macroura, Gray Catbirds Dumetella carolinensis, and Willow Flycatchers Empidonax traillii. Birds with quiet or low frequency songs are likely to be under-detected by UAV-based methods, due to masking by the drone noise of the quadcopter. Recordings of bird songs from ground-based recorders show that bird song output was slightly reduced when the quadcopter was overhead. The development of quieter quadcopters would overcome the masking and the possible behavioral response issues that we highlighted. We demonstrate that low-cost UAVs provide a useful new method of surveying songbirds that is accessible to organizations and researchers with restricted budgets

Trash on Arctic beach: Coastal pollution along Calypsostranda, Bellsund, Svalbard

Beach pollution is one of the most common hazards in present-day anthropogenic environments. Even in the remote Svalbard Archipelago, pollution impacts the beach system and can pose environmental threats. The significant increase in human activity observed in Svalbard over the last 20–30 years has resulted in a visible change in the amount of coastal pollution. A 5 km long transect of modern beach developed along Calypsostranda (Recherchefjorden, Bellsund) was surveyed in the summer of 2015 in order to characterize the beach pollution. During the survey 296 pieces of trash were found on beach surface. 82% of found trash was plastic, followed by glass (8%), and metal (5%). The comparison with previous pollution survey showed the significant increase of plastic waste in local beach environment. Similar problem has been recently recorded in other parts of Svalbard suggesting an urgent need for coastal pollution monitoring

Dense Freeze‐cast Li_7La_3Zr_2O_(12) Solid Electrolytes with Oriented Open Porosity and Contiguous Ceramic Scaffold

Freeze casting is used for the first time to prepare solid electrolyte scaffolds with oriented porosity and dense ceramic walls made of Li_7La_3Zr_2O_(12) (LLZO), one of the most promising candidates for solid state battery electrolytes. Processing parameters ‐ such as solvent solidification rate, solvent type, and ceramic particle size ‐ are investigated, focusing on their influence on porosity and ceramic wall density. Dendrite‐like porosity is obtained when using cyclohexane and dioxane as solvents. Lamellar porosity is observed in aqueous slurries resulting in a structure with the highest apparent porosity and densest ceramic scaffold but weakest mechanical properties due to the lack of interlamellar support. The use of smaller LLZO particle size in the slurries resulted in lower porosity and denser ceramic walls. The intrinsic ionic conductivity of the oriented LLZ ceramic scaffold is unaffected by the freeze casting technique, providing a promising ceramic scaffold for polymer infill in view of designing new types of ceramic‐polymer composites