At the liquid-gas phase transition in water, the density has a discontinuity at atmospheric pressure; however, the line of these first-order transitions defined by increasing the applied pressure ...terminates at the critical point
, a concept ubiquitous in statistical thermodynamics
. In correlated quantum materials, it was predicted
and then confirmed experimentally
that a critical point terminates the line of Mott metal-insulator transitions, which are also first-order with a discontinuous charge carrier density. In quantum spin systems, continuous quantum phase transitions
have been controlled by pressure
, applied magnetic field
and disorder
, but discontinuous quantum phase transitions have received less attention. The geometrically frustrated quantum antiferromagnet SrCu
(BO
)
constitutes a near-exact realization of the paradigmatic Shastry-Sutherland model
and displays exotic phenomena including magnetization plateaus
, low-lying bound-state excitations
, anomalous thermodynamics
and discontinuous quantum phase transitions
. Here we control both the pressure and the magnetic field applied to SrCu
(BO
)
to provide evidence of critical-point physics in a pure spin system. We use high-precision specific-heat measurements to demonstrate that, as in water, the pressure-temperature phase diagram has a first-order transition line that separates phases with different local magnetic energy densities, and that terminates at an Ising critical point. We provide a quantitative explanation of our data using recently developed finite-temperature tensor-network methods
. These results further our understanding of first-order quantum phase transitions in quantum magnetism, with potential applications in materials where anisotropic spin interactions produce the topological properties
that are useful for spintronic applications.
Planck pre-launch status: The Planck mission Crone, G.; Guyot, G.; Gregorio, A. ...
Astronomy and astrophysics (Berlin),
09/2010, Letnik:
520
Journal Article, Publication, Web Resource
Recenzirano
Odprti dostop
The European Space Agency's Planck satellite, launched on 14 May 2009, is the third-generation space experiment in the field of cosmic microwave background (CMB) research. It will image the ...anisotropies of the CMB over the whole sky, with unprecedented sensitivity (${{\Delta T}\over T}$ ~ 2 × 10-6) and angular resolution (~5 arcmin). Planck will provide a major source of information relevant to many fundamental cosmological problems and will test current theories of the early evolution of the Universe and the origin of structure. It will also address a wide range of areas of astrophysical research related to the Milky Way as well as external galaxies and clusters of galaxies. The ability of Planck to measure polarization across a wide frequency range (30-350 GHz), with high precision and accuracy, and over the whole sky, will provide unique insight, not only into specific cosmological questions, but also into the properties of the interstellar medium. This paper is part of a series which describes the technical capabilities of the Planck scientific payload. It is based on the knowledge gathered during the on-ground calibration campaigns of the major subsystems, principally its telescope and its two scientific instruments, and of tests at fully integrated satellite level. It represents the best estimate before launch of the technical performance that the satellite and its payload will achieve in flight. In this paper, we summarise the main elements of the payload performance, which is described in detail in the accompanying papers. In addition, we describe the satellite performance elements which are most relevant for science, and provide an overview of the plans for scientific operations and data analysis.
Abstract
The ReadOut System (ROS) is a central part of the data
acquisition (DAQ) system of the ATLAS Experiment at the CERN Large
Hadron Collider (LHC). The system is responsible for receiving and
...buffering event data from all detector subsystems and serving these
to the High Level Trigger (HLT) system via a 10 GbE network,
discarding or transporting data onward once the trigger has
completed its selection process. The ATLAS ROS was completely
replaced during the 2013–2014 experimental shutdown in order to
meet the demanding conditions expected during LHC Run 2 and Run 3
(2015–2025). The ROS consists of roughly one hundred Linux-based
2U-high rack-mounted servers equipped with PCIe I/O cards and
10 GbE interfaces. This paper documents the system requirements
for LHC Runs 2 and 3 and the design choices taken to meet them. The
results of performance measurements and the re-use of ROS technology
for the development of data sources, test platforms for other
systems, and another ATLAS DAQ system component, namely the Region
of Interest Builder (RoIB), are also discussed. Finally performance
results for Run 2 operations are presented before looking at the
upgrade for Run 3.
Translation and edition. The additional documents, in translation, comprise a letter by Antoine Malfante, 1447, an account of the voyages of Diogo Gomes, c. 1456, and extracts from João de Barros, ...Decadas de Asia. This is a new print-on-demand hardback edition of the volume first published in 1937. Owing to technical constraints it has not been possible to reproduce the map of "North-western Africa in the fifteenth century" which appeared in the first edition of the work.
The ALICE and ATLAS DAQ systems read out detector data via point-to-point serial links into custom hardware modules, the ALICE RORC and ATLAS ROBIN. To meet the increase in operational requirements ...both experiments are replacing their respective modules with a new common module, the C-RORC. This card, developed by ALICE, implements a PCIe Gen 2 x8 interface and interfaces to twelve optical links via three QSFP transceivers. This paper presents the design of the C-RORC, its performance and its application in the ALICE and ATLAS experiments.
The ATLAS detector uses a real time selective triggering system to reduce the high interaction rate from 40 MHz to its data storage capacity of 1 kHz. A hardware first level (L1) trigger limits the ...rate to 100 kHz and a software high level trigger (HLT) selects events for offline analysis. The HLT uses the Regions of Interest (RoIs) identified by L1 and provided by the Region of Interest Builder (RoIB). The current RoIB is a custom VMEbus based system that operated reliably since the first run of the LHC . Since the LHC will reach higher luminosity and ATLAS will increase the complexity and number of L1 triggers, it is desirable to have a more flexible and more operationally maintainable RoIB in the future. In this regard, the functionality of the multi-card VMEbus based RoIB is being migrated to a PC based RoIB with a PCI-Express card. Testing has produced a system that achieved the targeted rate of 100 kHz.
Background
Knee disarticulations (KD) are most commonly employed following trauma or tumor resection but represent less than 2% of all lower extremity amputations performed in the United States ...annually. KDs provide enhanced proprioception, a long lever arm, preservation of adductor muscle insertion, decreased metabolic cost of ambulation, and an end weight-bearing stump. The role for KDs in the setting of arterial insufficiency or overwhelming infection is less clear. The purpose of this study is to describe technique modifications and report surgical outcomes following KDs at a high-volume Limb Salvage Center.
Methods
A retrospective study of medical records for all patients who underwent a through-knee amputation performed by the senior author (C.E.A.) between 2004 and 2012 was completed. Medical records were reviewed to collect demographic, operative, and postoperative information for each of the patients identified.
Results
Between 2004 and 2012, 46 through-knee amputations for 41 patients were performed. The mean patient age was 68 and indications for surgery included infection (56%), arterial thrombosis (35%), and trauma (9%). Postoperative complications included superficial cellulitis (13%), soft tissue infection (4%), and flap ischemia (4%) necessitating one case of surgical debridement (4%) and four trans-femoral amputations (9%). 9 (22%) patients went on to ambulate. Postoperative ambulation was greatest in the traumatic cohort and for patients less than 50 years of age, P<0.05. Alternatively, diabetes mellitus and infection reduced the likelihood of postoperative ambulation, P<0.01.
Conclusions
Knee disarticulations are a safe and effective alternative to other lower extremity amputations when clinically feasible. For patient unlikely to ambulate, a through-knee amputation maximizes ease of transfers, promotes mobility by providing a counterbalance, and eliminates the potential for knee flexion contracture with subsequent skin breakdown.
Herschel Space Observatory Pilbratt, G. L.; Riedinger, J. R.; Passvogel, T. ...
Astronomy and astrophysics (Berlin),
07/2010, Letnik:
518
Journal Article
Recenzirano
Herschel was launched on 14 May 2009, and is now an operational ESA space observatory offering unprecedented observational capabilities in the far-infrared and submillimetre spectral range 55–671 μm. ...Herschel carries a 3.5 m diameter passively cooled Cassegrain telescope, which is the largest of its kind and utilises a novel silicon carbide technology. The science payload comprises three instruments: two direct detection cameras/medium resolution spectrometers, PACS and SPIRE, and a very high-resolution heterodyne spectrometer, HIFI, whose focal plane units are housed inside a superfluid helium cryostat. Herschel is an observatory facility operated in partnership among ESA, the instrument consortia, and NASA. The mission lifetime is determined by the cryostat hold time. Nominally approximately 20 000 h will be available for astronomy, 32% is guaranteed time and the remainder is open to the worldwide general astronomical community through a standard competitive proposal procedure.
Cutaneous Manifestations of Vasculitis Xu, Lisa Y., MD; Esparza, Edward M., MD, PhD; Anadkat, Milan J., MD ...
Seminars in arthritis and rheumatism,
04/2009, Letnik:
38, Številka:
5
Journal Article
Recenzirano
Objectives To discuss the clinical features, diagnostic evaluation, and treatment options for cutaneous vasculitis. Methods The literature in the PubMed database was reviewed regarding the ...presentation, pathophysiology, clinical workup, and treatment of cutaneous vasculitis. Results Available classification criteria of vasculitis are based on histopathologic criteria or clinicohistologic features. These have been designed more for research purposes than for clinical application. Skin findings such as palpable purpura, nodules, urticaria, ulcers, and infarction are clues to the presence of vasculitis. Pathologic findings of fibrinoid necrosis, infiltration by neutrophils or lymphocytes, and deposition of complement and immunoglobulin may be helpful in reaching a specific diagnosis. However, there is considerable overlap across different conditions. Conclusions The correct diagnosis of cutaneous manifestations of vasculitis requires an understanding of vasculitis classification, recognition of specific clinical patterns, and the ability to interpret histopathologic data.
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