Fermi Surface of Cr1−x_{1-x}Vx_x across the Quantum Critical Point

We have measured de Haas-van Alphen oscillations of Cr$_{1-x}$V$_x$, $0 \le x \le 0.05$, at high fields for samples on both sides of the quantum critical point at $x_c=0.035$. For all samples we observe only those oscillations associated with a single small hole band with magnetic breakdown orbits of the reconstructed Fermi surface evident for $x<x_c$. The absence of oscillations from Fermi surface sheets most responsible for the spin density wave (SDW) in Cr for $x>x_c$ is further evidence for strong fluctuation scattering of these charge carriers well into the paramagnetic regime. We find no significant mass enhancement of the carriers in the single observed band at any $x$. An anomalous field dependence of the dHvA signal for our $x=0.035$ crystal at particular orientations of the magnetic field is identified as due to magnetic breakdown that we speculate results from a field induced SDW transition at high fields.Comment: 8 pages with 7 figure

River Clyde Environmental Change Network diatom analysis project final: report to SEPA

This report provides details of work performed on the SEPA contract to ENSIS Ltd. involving the preparation and analysis of historic (September 1994 – August 2010) Environmental Change Network diatom samples from the River Clyde at the Tidal Weir. Diatoms were collected from the site by SEPA, forwarded to ENSIS Ltd and prepared for analysis following protocols described in the United Kingdom Environmental Change Network’s “Protocols for Standard Measurements at Freshwater Sites” (Sykes et al., 1999). Samples were taken at the site at various times of year and a full list of those that have been received by ENSIS is provided in Appendix 1. For this project, in order to minimise any inter-seasonal variability in the time-series, Kate Arnold from SEPA selected a subset of 16 summer samples for analysis, all collected between late July and early September. Approximately 400 diatom valves were counted per sample by Gina Clarke using a light microscope with phase contrast at 1000x magnification. Count data were recorded on a spreadsheet and transferred to ENSIS where they have been added to the ECN diatom database and have also been provided to SEPA. The diatom count data was run through the DARLEQII program (Kelly et al, 2011) in order to generate Trophic Diatom Index (TDI), Ecological Quality Ratio (EQR) and status class values (high, good, moderate, poor, bad) for each sample. Alkalinity values for the calculations were provided by SEPA for all samples except the earliest three in the timeseries, for which the average from all samples was used. Both TDI3 and TDI4 scores were calculated for all samples and the scores reported here. Table 1 is taken from the DARLEQII user guide (Kelly et al, 2011) and describes the output fields provided in the results section for the site below. Electronic copies of the full DARLEQII program output have been provided to SEPA

PDFS: Practical Data Feed Service for Smart Contracts

Smart contracts are a new paradigm that emerged with the rise of the blockchain technology. They allow untrusting parties to arrange agreements. These agreements are encoded as a programming language code and deployed on a blockchain platform, where all participants execute them and maintain their state. Smart contracts are promising since they are automated and decentralized, thus limiting the involvement of third trusted parties, and can contain monetary transfers. Due to these features, many people believe that smart contracts will revolutionize the way we think of distributed applications, information sharing, financial services, and infrastructures. To release the potential of smart contracts, it is necessary to connect the contracts with the outside world, such that they can understand and use information from other infrastructures. For instance, smart contracts would greatly benefit when they have access to web content. However, there are many challenges associated with realizing such a system, and despite the existence of many proposals, no solution is secure, provides easily-parsable data, introduces small overheads, and is easy to deploy. In this paper we propose PDFS, a practical system for data feeds that combines the advantages of the previous schemes and introduces new functionalities. PDFS extends content providers by including new features for data transparency and consistency validations. This combination provides multiple benefits like content which is easy to parse and efficient authenticity verification without breaking natural trust chains. PDFS keeps content providers auditable, mitigates their malicious activities (like data modification or censorship), and allows them to create a new business model. We show how PDFS is integrated with existing web services, report on a PDFS implementation and present results from conducted case studies and experiments.Comment: Blockchain; Smart Contracts; Data Authentication; Ethereu

Burton Mill Pond vision and work programme

This Report, commissioned by West Sussex County Council, provides environmental and ecological evidence to determine the current conservation value and status of Burton Mill Pond (BMP), and builds the evidence into a vision for the site. Site management is discussed within the context of achieving this vision, and a work programme presented, from which WSCC can develop and detailed management schedule

The Fermi surface of CeCoIn5: dHvA

Measurements of the de Haas - van Alphen effect in the normal state of the heavy Fermion superconductor CeCoIn5 have been carried out using a torque cantilever at temperatures ranging from 20 to 500 mK and in fields up to 18 tesla. Angular dependent measurements of the extremal Fermi surface areas reveal a more extreme two dimensional sheet than is found in either CeRhIn5 or CeIrIn5. The effective masses of the measured frequencies range from 9 to 20 m*/m0.Comment: 4 pages, 2 figures, submitted to PRB Rapid

Large parallel and perpendicular electric fields on electron spatial scales in the terrestrial bow shock

Large parallel ($\leq$ 100 mV/m) and perpendicular ($\leq$ 600 mV/m) electric fields were measured in the Earth's bow shock by the vector electric field experiment on the Polar satellite. These are the first reported direct measurements of parallel electric fields in a collisionless shock. These fields exist on spatial scales comparable to or less than the electron skin depth (a few kilometers) and correspond to magnetic field-aligned potentials of tens of volts and perpendicular potentials up to a kilovolt. The perpendicular fields are amongst the largest ever measured in space, with energy densities of $\epsilon_0 E^2/ n k_b T_e$ of order 10%. The measured parallel electric field implies that the electrons can be demagnetized, which may result in stochastic (rather than coherent) electron heating

Analysis of sediment, fish and phytoplankton samples from Indawgyi Lake, Myanmar

Fauna and Flora International are coordinating a management plan for Indawgyi Lake (under consideration as a Ramsar and UNESCO World Heritage Site) in Myanmar. Part of this process will be to set-up monitoring protocols for the inflow/outflow streams and the lake. Potential impacts on the lake include artisanal gold mining in the in-flow streams, farming around the lake (mostly rice) and some waste inputs from villages. There are further concerns related to the introduction of invasive fish (Oreochromis niloticus – Nile tilapia) and plant (Eichhornia sp. ‘water hyacinth’) species. In 2015 the following samples were collected following advice from ENSIS: i) water samples to measure phosphate, nitrates and sulphates (and other N, P, and S species that may be appropriate)*; ii) river and lake sediments and biological material (fish biopsy from whole small fish or tissue from larger fish) to measure heavy metal concentrations (with key elements being mercury, arsenic, lead and copper). Fish samples were preserved in 100% ethanol. Samples were taken of sediment (in triplicate) from about 15 locations from tributary rivers and from the lake periphery (45 samples in total); iii) water column samples from Indawgyi Lake (10 cm below the surface) to measure algae abundance and algal species composition. Samples were preserved in Lugol's iodine, initially from 1 l of water but siphoned to about 150 ml final volume

Predicting magnetopause crossings at geosynchronous orbit during the Halloween storms

[1] In late October and early November of 2003, the Sun unleashed a powerful series of events known as the Halloween storms. The coronal mass ejections launched by the Sun produced several severe compressions of the magnetosphere that moved the magnetopause inside of geosynchronous orbit. Such events are of interest to satellite operators, and the ability to predict magnetopause crossings along a given orbit is an important space weather capability. In this paper we compare geosynchronous observations of magnetopause crossings during the Halloween storms to crossings determined from the Lyon-Fedder-Mobarry global magnetohydrodynamic simulation of the magnetosphere as well to predictions of several empirical models of the magnetopause position. We calculate basic statistical information about the predictions as well as several standard skill scores. We find that the current Lyon-Fedder-Mobarry simulation of the storm provides a slightly better prediction of the magnetopause position than the empirical models we examined for the extreme conditions present in this study. While this is not surprising, given that conditions during the Halloween storms were well outside the parameter space of the empirical models, it does point out the need for physics-based models that can predict the effects of the most extreme events that are of significant interest to users of space weather forecasts