Weed Control for Reduced Tillage Systems

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Assessment of Black Rail Status in North Carolina, Breeding Season 2017 and 2018 Summaries

The Black Rail (Laterallus jamaicensis) is the most secretive and least understood marsh bird in North America with the Eastern Black Rail (L. j. jamaicensis), one of two subspecies that occur here, listed as endangered in six states along the Atlantic Coast and proposed for federal listing under the Endangered Species Act (USFWS–R4–ES–2018–0057, 2018). Black Rails require dense vegetation for cover during all stages of their life cycle. They require wetlands with minimal water coverage during the breeding season. Historic population size for the Eastern subspecies was likely in the tens of thousands (25,000 to 100,000; Delaney and Scott 2002) but is now believed to be in the hundreds to low thousands. Eastern Black Rails breed within three geographic areas within North America including the Atlantic Coast, the Gulf Coast, and the Midwest. The Atlantic Coast has generally been thought to support the largest breeding population throughout the range with pairs mostly confined to the highest elevations within tidal salt marshes. The historic breeding range along the Atlantic Coast has contracted more than 450 kilometers south and the population is estimated to be declining by 9% annually (Watts 2016). The primary driver of declines over the past three decades is believed to be sea-level rise and associated tidal inundation during the nesting season. North Carolina has long been recognized as a stronghold for Black Rails within the mid-Atlantic region. Most of what we know about the distribution and abundance of Black Rails in the state is based on site specific surveys and scattered anecdotal records (Fussell and McCrimmon 1976, Fussell and Wilson 1983, Davis et al. 1988, Collazo et al. 1990, LeGrand 1993, Fussell 1994, Paxton and Watts 2002, Watts 2016). These reports have documented a number of tidal marsh breeding locations, a well-known larger population at the Cedar Island National Wildlife Refuge, and at Piney Island military installation (both in Carteret County). In the late 1800s and early 1900s Black Rails were documented in the western part of the state using agricultural fields but there have not been consistent records since that time (Lee 1999, Watts 2016). Prior to 2014, a comprehensive status assessment for Black Rails in North Carolina had not been conducted, nor were there any existing systematic monitoring programs in place to assess the health of Black Rail populations. The purpose of this project is to gain a systematic view of the distribution of Black Rails in coastal North Carolina to help determine their status and distribution, to expand upon previous survey locations from the 2014 and 2015 field seasons, to determine if Black Rails continue to occupy historic strongholds, and to initiate an inland survey centered on agricultural lands with high density freshwater wetlands, farm ponds, Carolina Bays, and other water features that Black Rails have historically used within the region. We designed a broad survey frame so sampling locations could be used for monitoring purposes into the future. During the 2017 field season, 284 coastal points were surveyed, and during the 2018 field season 192 points were surveyed. All points surveyed in 2017 were along the outer coast in tidal or impounded wetlands. During the 2018 survey, 169 inland points and 23 coastal points were surveyed. The 2018 coastal survey locations were comprised of a network of previously occupied areas from year 2000 on. Three rounds of surveys were conducted between 18 April and 20 July 2017 and between 1 May and 15 July 2018. All points were surveyed three times unless there were access issues during one of the survey rounds. We conducted a total of 1,394 individual play-back surveys, 844 in 2017 and 550 in 2018. We detected a minimum of 9 individual Black Rails at 4 survey points in 2017 and we detected zero Black Rails in 2018 for survey occupancy of .01% (4 of 476 total survey points). During the 2014 and 2015 breedin

Feedback Control of coupled-Bunch Instabilities

Abstract The next generation of synchrotron light sources and particle accelerators will require active feedback systems to control multi-bunch instabilities [1, Feedback systems to stabilize coupled-bunch instabilities may be understood in the frequency domain (modebased feedback) or in the time domain (bunch-by-bunch feedback). In both approaches an external amplifier system is used to create damping fields that prevent coupledbunch oscillations from growing without bound. The system requirements for transverse (betatron) and longitudinal (synchrotron) feedback are presented, and possible implementation options developed. Feedback system designs based on digital signal-processing techniques are described. Experimental results are shown from a synchrotron oscillation damper in the SSRLjSLAC storage ring SPEAR that uses digital signal-processing techniques

Childhood bullying, paranoid thinking, and the misappraisal of social threat: trouble at school

Background:Experiences of bullying predict the development of paranoia in school-age adolescents. While many instances of psychotic phenomena are transitory, maintained victimization can lead to increasingly distressing paranoid thinking. Furthermore, paranoid thinkers perceive threat in neutral social stimuli and are vigilant for environmental risk. Aims:The present paper investigated the association between different forms of bullying and paranoid thinking, and the extent to which school-age paranoid thinkers overestimate threat in interpersonal situations. Methods: Two hundred and thirty participants, aged between eleven and fourteen, were recruited from one secondary school in the UK. Participants completed a series of questionnaires hosted on the Bristol Online Survey tool. All data were collected in a classroom setting in quiet and standardized conditions. Results: A significant and positive relationship was found between experiences of bullying and paranoid thinking: greater severity of bullying predicted more distressing paranoid thinking. Further, paranoid thinking mediated the relationship between bullying and overestimation of threat in neutral social stimuli. Conclusion: Exposure to bullying is associated with distressing paranoid thinking and subsequent misappraisal of threat. As paranoid thinkers experience real and overestimated threat, the phenomena may persist

Inflight Radiometric Calibration of New Horizons' Multispectral Visible Imaging Camera (MVIC)

We discuss two semi-independent calibration techniques used to determine the in-flight radiometric calibration for the New Horizons' Multi-spectral Visible Imaging Camera (MVIC). The first calibration technique compares the observed stellar flux to modeled values. The difference between the two provides a calibration factor that allows the observed flux to be adjusted to the expected levels for all observations, for each detector. The second calibration technique is a channel-wise relative radiometric calibration for MVIC's blue, near-infrared and methane color channels using observations of Charon and scaling from the red channel stellar calibration. Both calibration techniques produce very similar results (better than 7% agreement), providing strong validation for the techniques used. Since the stellar calibration can be performed without a color target in the field of view and covers all of MVIC's detectors, this calibration was used to provide the radiometric keywords delivered by the New Horizons project to the Planetary Data System (PDS). These keywords allow each observation to be converted from counts to physical units; a description of how these keywords were generated is included. Finally, mitigation techniques adopted for the gain drift observed in the near-infrared detector and one of the panchromatic framing cameras is also discussed

The Small Satellites of Pluto as Observed by New Horizons

The New Horizons mission has provided resolved measurements of Pluto's moons Styx, Nix, Kerberos, and Hydra. All four are small, with equivalent spherical diameters of $\approx$40 km for Nix and Hydra and ~10 km for Styx and Kerberos. They are also highly elongated, with maximum to minimum axis ratios of $\approx$2. All four moons have high albedos ( $\approx$50-90 %) suggestive of a water-ice surface composition. Crater densities on Nix and Hydra imply surface ages $\gtrsim$ 4 Ga. The small moons rotate much faster than synchronous, with rotational poles clustered nearly orthogonal to the common pole directions of Pluto and Charon. These results reinforce the hypothesis that the small moons formed in the aftermath of a collision that produced the Pluto-Charon binary.Comment: in Science 351, aae0030 (2016