To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure email@example.com
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
An updated compilation of published and new data of major-ion (Ca, Cl, K, Mg, Na, NO3, SO4) and methylsulfonate (MS) concentrations in snow from 520 Antarctic sites is provided by the national ITASE (International Trans-Antarctic Scientific Expedition) programmes of Australia, Brazil, China, Germany, Italy, Japan, Korea, New Zealand, Norway, the United Kingdom, the United States and the national Antarctic programme of Finland. The comparison shows that snow chemistry concentrations vary by up to four orders of magnitude across Antarctica and exhibit distinct geographical patterns. The Antarctic-wide comparison of glaciochemical records provides a unique opportunity to improve our understanding of the fundamental factors that ultimately control the chemistry of snow or ice samples. This paper aims to initiate data compilation and administration in order to provide a framework for facilitation of Antarctic-wide snow chemistry discussions across all ITASE nations and other contributing groups. The data are made available through the ITASE web page (http://www2.umaine.edu/itase/content/syngroups/snowchem.html) and will be updated with new data as they are provided. In addition, recommendations for future research efforts are summarized.
A new generation of solar instruments provides improved spectral, spatial, and temporal resolution, thus facilitating a better understanding of dynamic processes on the Sun. High-resolution observations often reveal multiple-component spectral line profiles, e.g., in the near-infrared He i 10830 Å triplet, which provides information about the chromospheric velocity and magnetic fine structure. We observed an emerging flux region, including two small pores and an arch filament system, on 2015 April 17 with the ‘very fast spectroscopic mode’ of the GREGOR Infrared Spectrograph (GRIS) situated at the 1.5-meter GREGOR solar telescope at Observatorio del Teide, Tenerife, Spain. We discuss this method of obtaining fast (one per minute) spectral scans of the solar surface and its potential to follow dynamic processes on the Sun. We demonstrate the performance of the ‘very fast spectroscopic mode’ by tracking chromospheric high-velocity features in the arch filament system.
Introduction: Point of care ultrasound has become an established tool in the initial management of patients with undifferentiated hypotension. Current established protocols (RUSH, ACES, etc) were developed by expert user opinion, rather than objective, prospective data. We wished to use reported disease incidence to develop an informed approach to PoCUS in hypotension using a “4 F’s” approach: Fluid; Form; Function; Filling. Methods: We summarized the incidence of PoCUS findings from an international multicentre RCT, and using a modified Delphi approach incorporating this data we obtained the input of 24 international experts associated with five professional organizations led by the International Federation of Emergency Medicine. The modified Delphi tool was developed to reach an international consensus on how to integrate PoCUS for hypotensive emergency department patients. Results: Rates of abnormal PoCUS findings from 151 patients with undifferentiated hypotension included left ventricular dynamic changes (43%), IVC abnormalities (27%), pericardial effusion (16%), and pleural fluid (8%). Abdominal pathology was rare (fluid 5%, AAA 2%). After two rounds of the survey, using majority consensus, agreement was reached on a SHoC-hypotension protocol comprising: A. Core: 1. Cardiac views (Sub-xiphoid and parasternal windows for pericardial fluid, cardiac form and ventricular function); 2. Lung views for pleural fluid and B-lines for filling status; and 3. IVC views for filling status; B. Supplementary: Additional cardiac views; and C. Additional views (when indicated) including peritoneal fluid, aorta, pelvic for IUP, and proximal leg veins for DVT. Conclusion: An international consensus process based on prospectively collected disease incidence has led to a proposed SHoC-hypotension PoCUS protocol comprising a stepwise clinical-indication based approach of Core, Supplementary and Additional PoCUS views.
Introduction: Point of care ultrasound (PoCUS) provides invaluable information during resuscitation efforts in cardiac arrest by determining presence/absence of cardiac activity and identifying reversible causes such as pericardial tamponade. There is no agreed guideline on how to safely and effectively incorporate PoCUS into the advanced cardiac life support (ACLS) algorithm. We consider that a consensus-based priority checklist using a “4 F’s” approach (Fluid; Form; Function; Filling), would provide a better algorithm during ACLS. Methods: The ultrasound subcommittee of the Australasian College for Emergency Medicine (ACEM) drafted a checklist incorporating PoCUS into the ACLS algorithm. This was further developed using the input of 24 international experts associated with five professional organizations led by the International Federation of Emergency Medicine. A modified Delphi tool was developed to reach an international consensus on how to integrate ultrasound into cardiac arrest algorithms for emergency department patients. Results: Consensus was reached following 3 rounds. The agreed protocol focuses on the timing of PoCUS as well as the specific clinical questions. Core cardiac windows performed during the rhythm check pause in chest compressions are the sub-xiphoid and parasternal cardiac views. Either view should be used to detect pericardial fluid, as well as examining ventricular form (e.g. right heart strain) and function, (e.g. asystole versus organized cardiac activity). Supplementary views include lung views (for absent lung sliding in pneumothorax and for pleural fluid), and IVC views for filling. Additional ultrasound applications are for endotracheal tube confirmation, proximal leg veins for DVT, or for sources of blood loss (AAA, peritoneal/pelvic fluid). Conclusion: The authors hope that this process will lead to a consensus-based SHoC-cardiac arrest guideline on incorporating PoCUS into the ACLS algorithm.
Co-morbid disorders of conduct and emotions can be regarded as childhood antecedents of further negative developments (e.g. manifestation of personality disorders in adulthood). We evaluated a manualized psychodynamic therapy (PDT) for adolescents with these co-morbid disorders.
In a randomized controlled trial (RCT), 66 adolescents diagnosed with mixed disorders of conduct and emotions (F92 in ICD-10) were randomly assigned to a manualized in-patient PDT group or a waiting list/treatment-as-usual (WL/TAU) control condition. Diagnoses according to DSM-IV were also documented. Patients were compared using rates of remission as the primary outcome. The Global Severity Index (GSI) and the Strengths and Difficulties Questionnaire (SDQ) were used as secondary measures. Assessments were performed at baseline, post-treatment and at the 6-month follow-up.
The sample consisted of severely impaired adolescents with high rates of further co-morbid disorders and academic failure. Patients in the treatment group had a significantly higher rate of remission [odds ratio (OR) 26.41, 95% confidence interval (CI) 6.42–108.55, p < 0.001]. Compared with the control group, the PDT group resulted in significantly better outcomes on the SDQ (p = 0.04) but not the GSI (p = 0.18), with small between-group effect sizes (SDQ: d = 0.38, GSI: d = 0.18). However, the scores of patients treated with PDT were post-treatment no longer significantly different from normative data on the GSI and within the normal range on the SDQ. The effects in the treatment group were stable at follow-up. Furthermore, most patients were reintegrated into educational processes.
PDT led to remarkable improvement and furthered necessary preconditions for long-term stabilization. In future, PDT should be compared to other strong active treatments.
The Herschel Key Project SHINING performs a study of the ISM in star forming and active
infrared bright galaxies (starbursts, AGN, (U)LIRGs, interacting and low metallicity
galaxies) at local and intermediate redshifts. Here we present some surprising and
promising first results from parts of this programme, including spatially resolved PDR
diagnostics, line deficit diagnostics, and large scale molecular outflows traced by the OH
Nano-alloyed p-type Sb2Te3 and n-type Bi2Te3 thin films were grown on SiO2/Si and BaF2 substrates by molecular beam epitaxy (MBE) in two steps: (i) Repeated deposition of five-layer stacks with sequence Te-X-Te-X-Te (X = Sb or Bi) with elemental layer thicknesses of 0.2 nm on substrates at room temperature, (ii) annealing at 250 °C for two hours at which phase formation of Sb2Te3 or Bi2Te3 occurred. The room temperature MBE deposition method reduces surface roughness, allows the use of non lattice-matched substrates, and yields a more accurate and easier control of the Te content compared to Bi2Te3 thin films, which were epitaxially grown on BaF2 substrates at 290 °C. X-ray diffraction revealed that the thin films were single phase, poly-crystalline, and textured. The films showed grain sizes of 500 nm for Sb2Te3 and 250 nm for Bi2Te3, analyzed by transmission electron microscopy (TEM). The in-plane transport properties (thermopower S, electrical conductivity σ, charge carrier density n, charge carrier mobility μ, power factor S2σ) were measured at room temperature. The nano-alloyed Sb2Te3 thin film revealed a remarkably high power factor of 29 μW cm-1 K-2 similar to epitaxially grown Bi2Te3 thin films and Sb2Te3 single crystalline bulk materials. This large power factor can be attributed to a high charge carrier mobility of 402 cm2 V−1 s-1 similar to high-ZT Bi2Te3/Sb2Te3 superlattices. However, for the nano-alloyed Bi2Te3 thin film a low power factor of 8 μW cm−1 K-2 and a low charge carrier mobility of 80 cm2 V−1 s−1 were found. Detailed microstructure and phase analyses were carried out by energy-filtered TEM in cross-sections. Quantitative chemical analysis by energy-dispersive x−ray spectroscopy (EDS) was also applied. In Bi2Te3 thin films, few nanometer thick Bi-rich blocking layers at grain boundaries and Te fluctuations by 1.3 at.% within the grains were observed. The small charge carrier densities are explained by a reduced antisite defect density due to the low temperatures to which the thin films were exposed during annealing.
Energy-filtered transmission electron microscopy (EFTEM) yields new possibilities for the investigation of Bi2Te3 based nanomaterials. Combined low-loss electron energy-loss spectroscopy (EELS) and energy-dispersive x-ray microanalysis (EDS) and energy-filtered TEM were applied on a Zeiss 912Ω TEM to investigate nanowires, thin films, and bulk materials. Multilayered Bi-Sb-Te nanowires with a diameter of 65 nm and a period of 200 nm and stoichiometric Bi2Te3 nanowires were grown by potential-pulsed electrochemical deposition. Tellurium elemental maps of the multilayered nanowires were obtained by two-window edge-jump ratio images (EJI). EDS chemical analysis showed that small Te fluctuations of 3 at.% yielded significant contrast in EJI. Energy-filtered TEM applied on nano-alloyed Bi2Te3 thin films grown by molecular beam epitaxy (MBE) revealed 10-20 nm thick Bi-rich blocking layers at grain boundaries. Plasmon spectroscopy by EELS was applied on Bi2(Te0.91Se0.09)3 bulk and yielded a plasmon energy of 16.9 eV. Finally, plasmon dispersion was measured for Bi2(Te0.91Se0.09)3 bulk by angle-resolved EELS, which yields a fingerprint of the anisotropy and the dimensionality of the electronic structure of the materials.
In this study, we describe X‐ray absorption measurements designed to determine the influence of subsitutents on the location of dopants, the valence of dopants, structural changes, and modifications of electronic densities of states. Several possible mechanisms are offered which may elucidate Tc suppression due to metal dopings.
We have prepared in situ REBa2Cu3O7 (REBCO) (RE= Y, Pr, Dy) thin films and YBC0/Dy(Pr)BC0 superlattices by single target dc planar magnetron sputtering. YBCO/DyBCO superlattices have been realized with modulation wavelength as short as 24Å, i.e., a unit cell of YBCO alternates with a unit cell of DyBCO, on average. The superconducting properties of such superlattices are indistinguishable from those of single layers. Tco's (zero resistance) are between 85 and 89K, and the residual resistivity ratios are between 2.5 and 3. In contrast to these results, when YBCO is layered with PrBCO, which is insulating, a dramatic change in the superconducting properties is observed. We have been able to artificially vary the coupling between single 12Å unit cell of YBCO by interposing insulating planes of PrBCO. As the YBCO layer separation increases, T is reduced and the transition broadens showing evidence of 2‐D superconducting fluctuations.
The infrared (IR) absorption technique concurrent with thermal annealing was used to study the isolated AsGa antisite and an EL2-like defect in thermal neutron irradiated GaAs samples grown by the liquid-encapsulated Czochralski (LEC) technique. The residual absorption (unquenchable component) of the IR absorpion spectrum, after EL2 is completely photoquenched, is interpreted as the photoionization of the isolated ASGa antisite. This interpretation is supported by thermal annealing results at 600 C and by the increase of the unquenchable component as the irradiation dose is increased. A thermally unstable EL2-like defect is observed in heavily irradiated GaAs samples after 6 min annealing at 600 C. Thermal annealing kinetics show that the EL2-like defect is composed of three point defects.
The linewidth and peak position (vo) of the intersubband transition (IT) in GaAs/Al0.3Ga0.7As multiple quantum wells are studied as a function of temperature using the infrared absorption technique. We find that electrons in the GaAs well are weakly coupled to the GaAs normal optical phonon mode. The total integrated area of IT absorption is found to be approximately constant in the samples that were doped in the well but temperature dependent in the samples that were doped in the barrier. We also find that vo increases as the temperature decreases. This blue shift is found to increase as the dopant concentration is increased. We calculated the absorption spectrum in a nonparabolic-anisotropic envelope function approximation including temperature dependent effective masses, nonparbolicity, conduction band offsets, the Fermi level, and lineshape broadening. Our results indicate that a large manybody correction, in particular an exchange interaction (Eexch) for the ground state, is necessary to account for the observed blue shift as the dopant concentration increases.
The specific heats of β-B and of B4C have been reviewed, and measurements of a different sample of B4C have been carried out below 80 K. A specific heat anomaly observed previously in boron carbides has been shown to be extrinsic in origin. The thermal conductivity of B1−x Cx, for x < 0.20, between 0.2 and 2000 K has also been reviewed, and recent measurements have been added. The magnitude and temperature dependence of the conductivity are somewhat similar to what is expected for amorphous boron, except for the characteristic plateau which is not clearly discernible. A possible explanation for the strong phonon scattering is discussed.
The infrared absorption technique is used to study the recovery of the EL2 metastable state in semi-insulating GaAs under monochromatic light illumination. The induced optical recovery is monitored after low intensity (≤ 2mW/cm2) irradiation in the energy range 0.7 ≤ hv ≤ 1.5 eV. The data exhibit a complex structure consisting of a broad band around 0.9 eV and a set of multiple sharp peaks between 1.44 and 1.5 eV. This recovery is strongly dependent on the sample, temperature and illumination time. The present results suggest that a) the existing data and theoretical predictions for the isolated AsGa antisite structure are not compatable with the optical recovery data, b) EL2 is affected dramatically by other defects (traps) present in the sample and c) the peaks observed in the optical recovery data are coincident with the arsenic vacancy energy levels and therefore the present results support the proposed complex models involving an arsenic vacancy.
The temperature and polarization dependence of the optical absorption in ZnGeP2 at two micrometers is reported for the first time over the temperature range from 10K to 300K. The radiation was normally incident upon the face of a cubic sample which contained the c-axis. The absorption of o-rays (E parallel to c), and erays (E perpendicular to c) was determined. It was found that the e-ray absorption coefficient was always significantly larger than the o-ray absorption coefficient and that it had a less significant temperature dependence. For example, the ratio of e-ray to o-ray absorption coefficient was approximately two at 300K and five at 77K. Correspondingly the o-ray absorption coefficients were reduced upon cooling to 77K by a factor of 2.5, while the e-ray absorption coefficients were reduced only slightly (10%-20%). These results indicate that for Type I optical parametric oscillators (OPOs) which use an oray pump beam, that performance may be improved by cooling the crystal.
We report on ferroelectric field effect experiments in ultrathin layers of the metallic perovskite SrRuC<3 using Pb(Zr0.52Ti0.48)O3/SrRuO3 epitaxial heterostructures. Switching the ferroelectric polarization of the Pb(Zr0.52Ti0.48)O3 layer induces a ∼ 10% change in the sheet resistance of the SrRuO3 layer that is nonvolatile and also reversible. Hall effect measurements that take into account the anomalous Hall effect reveal a carrier concentration of n ∼ 2 × 1022 electrons/cm3 and allow us to understand quantitatively the sign and magnitude of the observed resistance change. Of key importance for these experiments is the crystalline and surface quality of the SrRuO3 and Pb(Zr0.52Ti0.48)O3 layers. We also discuss how this general approach of nonvolatile doping using ferroelectrics opens new possibilities of directly creating small electronic structures without using traditional lithographic techniques.