2,048 research outputs found

    A Two-Dimensional, Self-Consistent Model of Galactic Cosmic Rays in the Heliosphere

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    We present initial results from our new two-dimensional (radius and latitude), self-consistent model of galactic cosmic rays in the heliosphere. We focus on the latitudinal variations in the solar wind flow caused by the energetic particles. Among other things our results show that the cosmic rays significantly modify the latitudinal structure of the solar wind flow downstream of the termination shock. Specifically, for A>0 (corresponding to the present solar minimum) the wind beyond the shock is driven towards the equator, resulting in a faster wind flow near the current sheet, while for A<0 the effect is reversed and the wind turns towards the pole, with a faster flow at high latitudes. We attribute this effect to the latitudinal gradients in the cosmic ray pressure, caused by drifts, that squeeze the flow towards the ecliptic plane or the pole, respectively.Comment: 10 pages, 4 Postscript figures, uses AAS LaTeX v4.0, to be published in The Astrophysical Journal Letter

    cDrake CPIES Data Report November 2007 to December 2011

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    The goal of cDrake is to quantify the transport and understand the dynamic balances of the Antarctic Circumpolar Current (ACC) in Drake Passage. For this purpose, a transport line spanning all of Drake Passage and a local dynamics array of CPIES were deployed for a period of four years. A CPIES comprises an inverted echo sounder equipped with a bottom pressure gauge and a current meter tethered 50 m above the bottom. In addition to the CPIESs, three current meter moorings were deployed along the continental margins for the initial two years of the field program. Subsequently, a current meter comparison mooring was deployed in a region of strong bottom currents for a period of one year. Conductivity-temperature-depth and lowered acoustic Doppler current profiler measurements were taken at each CPIES site. Shipboard acoustic Doppler current profiler measured the velocity structure along the cruise track. In this report, the CPIES data collected during the field experiment are presented. The collection, processing and calibration of the CPIES are described

    Cascadia Pilot Experiment Data Report

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    This report documents the processing of data collected from an line of inverted echo sounders equipped with bottom pressure gauges and current meters (CPIES) deployed offshore of Oregon in the Cascadia subduction zone region from April to November 2017. The line consisted of four URI-model CPIES across the continental slope, spanning water depths from 2900 m to 1300 m. From offshore to onshore, the sites were designated O1, O1.5, O2 and O3. The instrument spacing telescoped toward the coast from 3.5 km to 7 km to 9 km. CTDs were taken at each site on the deployment and recovery cruises. Additionally, two Sonardyne-model PIES (lacking the integrated current meter) were colocated at the deepest and shallowest sites (O1 and O3) for comparison tests. An Aanderaa Seaguard current meter was moored in August 2017 at site O2 because the status of CPIES current meter at that location was uncertain

    PIES and CPIES Data Processing Manual

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    The Inverted Echo Sounder (IES) is an ocean bottom-moored instrument that measures the vertical acoustic travel time (VATT) round-trip from the seafloor to the sea surface and back. The VATT varies principally due to changes in the temperature profile of the water column, making the IES well-suited for monitoring changes in temperature structure and dynamic height (baroclinic signal). Currently, the Model 6.2, a combined IES, data-logger, and acoustic release, with measurements of bottom pressure and temperature (PIES) and optional measurements of current speed and direction (CPIES, with attached Aanderaa Doppler current sensor) is produced at URI/GSO. Data are processed in situ and are available (optional) remotely by an acoustic telemetry link. In addition to the IES-measured baroclinic signals, barotropic near-bottom pressure variations may be measured with the optional pressure sensor. A report was written in 1991 describing IES data processing [Fields et al., 1991]. Since that report, significant improvements have been made to both IES hardware and software, warranting an update of the IES data processing. The report by Kennelly et al. [2007] documents the standard processing steps contained in IESpkg 3, which has been used since the early 2000s, for IES/PIES/CPIES Models 6.1 and 6.2 at URI/GSO. More recently, IESpkg 4 was developed to allow more flexibility in the processing steps and data outputs, and to process the Fast PIES versions that sample 96 travel times each hour. This report documents the processing steps in IESpkg 4 and it repeats as much of the original text of Kennelly et al. [2007] as is still applicable. A separate document, Inverted Echo Sounder User\u27s Manual, IES Model 6.2, describes the IES hardware and instrument configuratio

    Zero-temperature generalized phase diagram of the 4d transition metals under pressure

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    We use an accurate implementation of density functional theory (DFT) to calculate the zero-temperature generalized phase diagram of the 4dd series of transition metals from Y to Pd as a function of pressure PP and atomic number ZZ. The implementation used is full-potential linearized augmented plane waves (FP-LAPW), and we employ the exchange-correlation functional recently developed by Wu and Cohen. For each element, we obtain the ground-state energy for several crystal structures over a range of volumes, the energy being converged with respect to all technical parameters to within 1\sim 1 meV/atom. The calculated transition pressures for all the elements and all transitions we have found are compared with experiment wherever possible, and we discuss the origin of the significant discrepancies. Agreement with experiment for the zero-temperature equation of state is generally excellent. The generalized phase diagram of the 4dd series shows that the major boundaries slope towards lower ZZ with increasing PP for the early elements, as expected from the pressure induced transfer of electrons from spsp states to dd states, but are almost independent of PP for the later elements. Our results for Mo indicate a transition from bcc to fcc, rather than the bcc-hcp transition expected from spsp-dd transfer.Comment: 28 pages and 10 figures. Submitted to Phys. Rev.

    Estimates of Eddy Heat Flux Crossing the Antarctic Circumpolar Current from Observations in Drake Passage

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    The 4-yr measurements by current- and pressure-recording inverted echo sounders in Drake Passage produced statistically stable eddy heat flux estimates. Horizontal currents in the Antarctic Circumpolar Current (ACC) turn with depth when a depth-independent geostrophic current crosses the upper baroclinic zone. The dynamically important divergent component of eddy heat flux is calculated. Whereas full eddy heat fluxes differ greatly in magnitude and direction at neighboring locations within the local dynamics array (LDA), the divergent eddy heat fluxes are poleward almost everywhere. Case studies illustrate baroclinic instability events that cause meanders to grow rapidly. In the southern passage, where eddy variability is weak, heat fluxes are weak and not statistically significant. Vertical profiles of heat flux are surface intensified with ~50% above 1000 m and uniformly distributed with depth below. Summing poleward transient eddy heat transport across the LDA of −0.010 ± 0.005 PW with the stationary meander contribution of −0.004 ± 0.001 PW yields −0.013 ± 0.005 PW. A comparison metric, −0.4 PW, represents the total oceanic heat loss to the atmosphere south of 60°S. Summed along the circumpolar ACC path, if the LDA heat flux occurred at six “hot spots” spanning similar or longer path segments, this could account for 20%–70% of the metric, that is, up to −0.28 PW. The balance of ocean poleward heat transport along the remaining ACC path should come from weak eddy heat fluxes plus mean cross-front temperature transports. Alternatively, the metric −0.4 PW, having large uncertainty, may be high

    American Policy British Politics: Whole of Life Imprisonment and Transatlantic Influence

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    Since the abolition of the death penalty, life imprisonment in England and Wales has had a literal meaning with exceptional rarity. Now though, in the rejection of perceived interference by the European Court of Human Rights in domestic sentencing, the politics of whole of life imprisonment have become exposed, specifically, in the widening applicability of the tariff to those who kill police officers or prison guards. Borrowing from the politics of capital punishment in the USA, in both ‘acting out’ after a particular crime, and the prioritising of victim groups, the most severe penalty in England and Wales is increasingly beginning to mirror how the most severe punishment across the Atlantic is used, represented, and politicised

    An Intercomparison of Four Models of Current Meter in High Current Conditions in Drake Passage

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    Seven current meters representing four models were placed for an 11 month deployment on a stiffly buoyed mooring to intercompare their velocity measurements: two VMCMs, two Aanderaa RCM11s, two Aanderaa SEAGUARDSs, and a Nortek Aquadopp. The current meters were placed 6 m apart from each other at about 4000 m depth in an area of Drake Passage expected to have strong near-bottom currents, that were nearly independent of depth. Two high-current events occurred in bursts of semi-diurnal pulses lasting several days, one with peak speeds up to 67 cm/s and the other above 35 cm/s. The current speed measurements all agreed within about 5% when vector-averaged over simultaneous time intervals: the full time interval (198 days) when all instruments were working, and the two high-speed events lasting 21 days and 7 days. The VMCMs, chosen as the reference measurements, were found to measure the median of the mean-current magnitudes. The RCM11 and SEAGUARD current speeds had a nearly 1:1 relationship with the median. They agreed within 2% at higher speeds (35-70 cm/s), whereas in lower speed ranges (0-35 cm/s) the vector-averaged speeds for the RCM11s and SEAGUARDS were, respectively, 4-5% lower and 3-5% higher than the median. The Aquadopp current speeds were about 7% higher than the VMCMs over the range (0-40 cm/s) encountered through their shorter common time period
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