Measurement-driven dynamics for a coherently-excited atom

The phenomenon of telegraphing in a measurement-driven two-level atom was noted in Cresser et al. [Cresser, J.D.; Barnett, S.M.; Jeffers, J.; Pegg, D.T. Opt. Commun. 2006, 264, 352361]. Here we introduce two quantitative measures of telegraphing: one based on the accumulated measurement record and one on the evolution of the quantum state. We use these to analyse the dynamics of the atom over a wide range of parameters. We find, in particular, that the measures provide broadly similar statistics when the measurements are frequent, but differ widely when measurements are sparse. This is in line with intuition, and demonstrates the utility of both measures

Migrant Common Eider, Somateria mollissima, Collisions with Power Transmission Lines and Shortwave Communication Towers on the Tantramar Marsh in Southeastern New Brunswick

Between 1971 and 2009, 85 dead, injured, or grounded Common Eiders, Somateria mollissima, were recorded on the Tantramar Marsh in southeastern New Brunswick, apparently the result of collisions with power transmission lines and shortwave communication towers. Of 82 location observations, 53 (65%) were near a series of power transmission lines and 21 (26%) were in the vicinity of shortwave communication towers. Of the 85 birds observed, 43 (51%) were found dead, 18 (21%) were found alive on the ground with undetermined injuries, 5 (6%) were found alive with broken wings, and 9 birds (11%) were found alive with no obvious external injuries and were released in water. A further 10 live birds (12%) were observed on small bodies of water and appeared unable to fly. Occurrences appear to be predominantly during fall migration, with most sightings recorded between 9 October and 21 December (99%, n = 73). The effects of cumulative mortality on Common Eiders should be considered if further infrastructure within the Tantramar Marsh or infrastructure involving other known overland routes used by Common Eiders during migration is proposed

Inferring the rules of social interaction in migrating caribou

Social interactions are a significant factor that influence the decision-making of species ranging from humans to bacteria. In the context of animal migration, social interactions may lead to improved decision-making, greater ability to respond to environmental cues, and the cultural transmission of optimal routes. Despite their significance, the precise nature of social interactions in migrating species remains largely unknown. Here we deploy unmanned aerial systems to collect aerial footage of caribou as they undertake their migration from Victoria Island to mainland Canada. Through a Bayesian analysis of trajectories we reveal the fine-scale interaction rules of migrating caribou and show they are attracted to one another and copy directional choices of neighbours, but do not interact through clearly defined metric or topological interaction ranges. By explicitly considering the role of social information on movement decisions we construct a map of near neighbour influence that quantifies the nature of information flow in these herds. These results will inform more realistic, mechanism-based models of migration in caribou and other social ungulates, leading to better predictions of spatial use patterns and responses to changing environmental conditions. Moreover, we anticipate that the protocol we developed here will be broadly applicable to study social behaviour in a wide range of migratory and non-migratory taxa. This article is part of the theme issue ‘Collective movement ecology’

Patterned probes for high precision 4D-STEM bragg measurements.

Nanoscale strain mapping by four-dimensional scanning transmission electron microscopy (4D-STEM) relies on determining the precise locations of Bragg-scattered electrons in a sequence of diffraction patterns, a task which is complicated by dynamical scattering, inelastic scattering, and shot noise. These features hinder accurate automated computational detection and position measurement of the diffracted disks, limiting the precision of measurements of local deformation. Here, we investigate the use of patterned probes to improve the precision of strain mapping. We imprint a "bullseye" pattern onto the probe, by using a binary mask in the probe-forming aperture, to improve the robustness of the peak finding algorithm to intensity modulations inside the diffracted disks. We show that this imprinting leads to substantially improved strain-mapping precision at the expense of a slight decrease in spatial resolution. In experiments on an unstrained silicon reference sample, we observe an improvement in strain measurement precision from 2.7% of the reciprocal lattice vectors with standard probes to 0.3% using bullseye probes for a thin sample, and an improvement from 4.7% to 0.8% for a thick sample. We also use multislice simulations to explore how sample thickness and electron dose limit the attainable accuracy and precision for 4D-STEM strain measurements

Quantifying physiological influences on otolith microchemistry

Trace element concentrations in fish earstones (‘otoliths’) are widely used to discriminate spatially discrete populations or individuals of marine fish, based on a commonly held assumption that physiological influences on otolith composition are minor, and thus variations in otolith elemental chemistry primarily reflect changes in ambient water chemistry. We carried out a long-term (1-year) experiment, serially sampling seawater, blood plasma and otoliths of mature and immature European plaice (Pleuronectes platessa L.) to test relationships between otolith chemistry and environmental and physiological variables. Seasonal variations in otolith elemental composition did not track seawater concentrations, but instead reflected physiological controls on metal transport and biokinetics, which are likely moderated by ambient temperature. The influence of physiological factors on otolith composition was particularly evident in Sr/Ca ratios, the most widely used elemental marker in applied otolith microchemistry studies. Reproduction also triggered specific variations in otolith and blood plasma metal chemistry, especially Zn/Ca ratios in female fish, which could potentially serve as retrospective spawning indicators. The influence of physiology on the trace metal composition of otoliths may explain the success of microchemical stock discrimination in relatively homogenous marine environments, but could complicate alternative uses for trace element compositions in biominerals of higher organism

Details of Eastern Coyote, Canis latrans, Predation on Great Black-backed Gull, Larus marinus, Eggs on Boot Island National Wildlife Area, Nova Scotia

We detail field observations of Eastern Coyote eating Great Black-backed Gull eggs for the first time in the literature. Photographic evidence of the remaining egg shells allowed us to identify the Coyote as the predator

PENGARUH TINGKAT PENDIDIKAN DAN PEKERJAAN TERHADAP ORAL HYGIENE PADA IBU HAMIL DI RSUD MEURAXA BANDA ACEH

ABSTRAKNama: Muhammad AdriansyahProgram Studi: Kedokteran GigiJudul:Pengaruh Tingkat Pendidikan dan Pekerjaan Terhadap Oral Hygiene pada Ibu Hamil di RSUD Meuraxa Banda AcehPendidikan adalah faktor sosial ekonomi yang mempengaruhi status kesehatan. Pekerjaan dihubungkan dengan tingkat pendidikan dan penghasilan, dimana pekerjaan membutuhkan latar belakang pendidikan yang tinggi, dan penghasilan dimana seseorang mempunyai penghasilan lebih besar maka akan mampu memenuhi kebutuhan dalam menjaga kesehatan gigi dan mulut. Selama masa kehamilan, wanita mengalami beberapa perubahan fisiologis yang menyebabkan terjadinya perubahan hormonal. Perubahan fisiologis juga berdampak pada perubahan menjaga kesehatan gigi dan mulut, sehingga wanita hamil lebih rentan terkena masalah gigi dan mulut. Tujuan penelitian ini adalah untuk mengetahui pengaruh tingkat pendidikan dan pekerjaan terhadap oral hygiene pada ibu hamil di RSUD Meuraxa Banda Aceh. Jenis penelitian ini bersifat analitik dengan metode cross sectional untuk melihat hubungan antar dua variabel. Penelitian ini melibatkan 48 subjek yang memenuhi kriteria inklusi. Subjek penelitian mengisi kuisioner yang diberikan serta diperiksa tingkat kebersihan rongga mulutnya. Data dianalisis dengan SPSS menggunakan Korelasi Spearman. Hasil uji menunjukkan ada pengaruh yang signifikan antara tingkat pendidikan (

Convection in a mushy-layer along a heated wall

Motivated by the mushy zones of sea ice, volcanoes, and icy moons of the outer solar system, we perform a theoretical and numerical study of boundary-layer convection along a vertical heated wall in a bounded ideal mushy region. The mush is comprised of a porous and reactive binary alloy with a mixture of saline liquid in a solid matrix, and is studied in the near-eutectic approximation. Here we demonstrate the existence of four regions and study their behavior asymptotically. Starting from the bottom of the wall, the four regions are (i) an isotropic corner region; (ii) a buoyancy dominated vertical boundary layer; (iii) an isotropic connection region; and (iv) a horizontal boundary layer at the top boundary with strong gradients of pressure and buoyancy. Scalings from numerical simulations are consistent with the theoretical predictions. Close to the heated wall, the convection in the mushy layer is similar to a rising buoyant plume abruptly stopped at the top, leading to increased pressure and temperature in the upper region, whose impact is discussed as an efficient melting mechanism

Accurate quantification of lattice temperature dynamics from ultrafast electron diffraction of single-crystal films using dynamical scattering simulations

In ultrafast electron diffraction (UED) experiments, accurate retrieval of time-resolved structural parameters such as atomic coordinates and thermal displacement parameters requires an accurate scattering model. Unfortunately, kinematical models are often inaccurate even for relativistic electron probes, especially for dense, oriented single crystals where strong channeling and multiple scattering effects are present. This article introduces and demonstrates dynamical scattering models tailored for quantitative analysis of UED experiments performed on single-crystal films. As a case study, we examine ultrafast laser heating of single-crystal gold films. Comparison of kinematical and dynamical models reveals the strong effects of dynamical scattering within nm-scale films and their dependence on sample topography and probe kinetic energy. Applied to UED experiments on an 11 nm thick film using 750 keV electron probe pulses, the dynamical models provide a tenfold improvement over a comparable kinematical model in matching the measured UED patterns. Also, the retrieved lattice temperature rise is in very good agreement with predictions based on previously measured optical constants of gold, whereas fitting the Debye-Waller factor retrieves values that are more than three times lower. Altogether, these results show the importance of dynamical scattering theory for quantitative analysis of UED, and demonstrate models that can be practically applied to single-crystal materials and heterostructures.Comment: 12 pages, 7 figure