Accountability Vol. 5 No. 2 Desember 2016

Accountability Vol. 5 No. 2 Desember 201

Cosmology

Cosmology lecture slides, maximally re-using or contributing free-licensed materials to Wikimedia commons. The full package for generating this pdf or an updated version is available at https://codeberg.org/boud/cosmology_lecture

Stability of the M2 Phase of Vanadium Dioxide Induced by Coherent Epitaxial Strain

Tensile strain along the cR axis in epitaxial VO2 films raises the temperature of the metal insulator transition and is expected to stabilize the intermediate monoclinic M2 phase. We employ surface-sensitive x-ray spectroscopy to distinguish from the TiO2 substrate and identify the phases of VO2 as a function of temperature in epitaxial VO2/TiO2 thin films with well-defined biaxial strain. Although qualitatively similar to our Landau-Ginzburg theory predicted phase diagrams, the M2 phase is stabilized by nearly an order of magnitude more strain than expected for the measured temperature window. Our results reveal that the elongation of the cR axis is insufficient for describing the transition pathway of VO2 epitaxial films and that a strain induced increase of electron correlation effects must be considered

Search For Continuous Gravitational Waves From 20 Accreting Millisecond X-Ray Pulsars In O3 LIGO Data

Results are presented of searches for continuous gravitational waves from 20 accreting millisecond x-ray pulsars with accurately measured spin frequencies and orbital parameters, using data from the third observing run of the Advanced LIGO and Advanced Virgo detectors. The search algorithm uses a hidden Markov model, where the transition probabilities allow the frequency to wander according to an unbiased random walk, while the J-statistic maximum-likelihood matched filter tracks the binary orbital phase. Three narrow subbands are searched for each target, centered on harmonics of the measured spin frequency. The search yields 16 candidates, consistent with a false alarm probability of 30% per subband and target searched. These candidates, along with one candidate from an additional target-of-opportunity search done for SAX J1808.4-3658, which was in outburst during one month of the observing run, cannot be confidently associated with a known noise source. Additional follow-up does not provide convincing evidence that any are a true astrophysical signal. When all candidates are assumed nonastrophysical, upper limits are set on the maximum wave strain detectable at 95% confidence, h095%. The strictest constraint is h095% = 4.7 x 10-26 from IGR J17062-6143. Constraints on the detectable wave strain from each target lead to constraints on neutron star ellipticity and r-mode amplitude, the strictest of which are ϵ95% = 3.1 x 10-7 and α95% = 1.8 x 10-5 respectively. This analysis is the most comprehensive and sensitive search of continuous gravitational waves from accreting millisecond x-ray pulsars to date

World cities and peripheral development: The interplay of gateways and subordinate places in Argentina and Ghana’s upstream oil and gas sector

Serving as “gateways”, some world cities tie their wider hinterlands to global networks. The article revisits gateway–hinterland relations against the backdrop of assessments that lead to opposed conclusions on the benefits and shortcomings of integration into the world economy. Referring to the oil and gas sector in Argentina and Ghana, it answers the question of how gateways interact with subordinate places and also uncovers obstacles to peripheral development. The author finds that Accra and Buenos Aires concentrate corporate control. Argentina's capital serves as a gateway for knowledge generation and logistics too. Opportunities for peripheral development in both countries are considerable, albeit largely limited to generic services. Besides a certain concentration of business activities in the gateway cities, more important challenges to peripheral development are typical for small and medium enterprises (insufficient finance and management capabilities, unawareness of business opportunities, and the like). They include rent seeking and subcontracting. The latter leaves local companies in a particularly weak position vis‐à‐vis lead firms. The author argues that while integration into the world economy allows for peripheral development, the corresponding outcomes may not meet everyone's expectations. Related expectations must, therefore, be more down‐to‐earth than overly optimistic statements frequently made by politicians

Intraoperative ventilator settings and their association with postoperative pulmonary complications in neurosurgical patients : post-hoc analysis of LAS VEGAS study

Background Limited information is available regarding intraoperative ventilator settings and the incidence of postoperative pulmonary complications (PPCs) in patients undergoing neurosurgical procedures. The aim of this post-hoc analysis of the 'Multicentre Local ASsessment of VEntilatory management during General Anaesthesia for Surgery' (LAS VEGAS) study was to examine the ventilator settings of patients undergoing neurosurgical procedures, and to explore the association between perioperative variables and the development of PPCs in neurosurgical patients. Methods Post-hoc analysis of LAS VEGAS study, restricted to patients undergoing neurosurgery. Patients were stratified into groups based on the type of surgery (brain and spine), the occurrence of PPCs and the assess respiratory risk in surgical patients in Catalonia (ARISCAT) score risk for PPCs. Results Seven hundred eighty-four patients were included in the analysis; 408 patients (52%) underwent spine surgery and 376 patients (48%) brain surgery. Median tidal volume (V-T) was 8 ml [Interquartile Range, IQR = 7.3-9] per predicted body weight; median positive end-expiratory pressure (PEEP) was 5 [3 to 5] cmH(2)0. Planned recruitment manoeuvres were used in the 6.9% of patients. No differences in ventilator settings were found among the sub-groups. PPCs occurred in 81 patients (10.3%). Duration of anaesthesia (odds ratio, 1.295 [95% confidence interval 1.067 to 1.572]; p = 0.009) and higher age for the brain group (odds ratio, 0.000 [0.000 to 0.189]; p = 0.031), but not intraoperative ventilator settings were independently associated with development of PPCs. Conclusions Neurosurgical patients are ventilated with low V-T and low PEEP, while recruitment manoeuvres are seldom applied. Intraoperative ventilator settings are not associated with PPCs

Expansion of the Tetragonal Magnetic Phase with Pressure in the Iron Arsenide Superconductor Ba₁₋ₓKₓFe₂As₂

In the temperature-concentration phase diagram of most iron-based superconductors, antiferromagnetic order is gradually suppressed to zero at a critical point, and a dome of superconductivity forms around that point. The nature of the magnetic phase and its fluctuations is of fundamental importance for elucidating the pairing mechanism. In Ba1-xKxFe2As2 and Ba1-xNaxFe2As2, it has recently become clear that the usual stripelike magnetic phase, of orthorhombic symmetry, gives way to a second magnetic phase, of tetragonal symmetry, near the critical point, in the range from x = 0.24 to x=0.28 for Ba1-xKxFe2As2. In a prior study, an unidentified phase was discovered for x \u3c 0.24 but under applied pressure, whose onset was detected as a sharp anomaly in the resistivity. Here we report measurements of the electrical resistivity of Ba1-xKxFe2As2 under applied hydrostatic pressures up to 2.75 GPa, for x = 0.22, 0.24, and 0.28. The critical pressure above which the unidentified phase appears is seen to decrease with increasing x and vanish at x = 0.24, thereby linking the pressure-induced phase to the tetragonal magnetic phase observed at ambient pressure. In the temperature-concentration phase diagram of Ba1-xKxFe2As2, we find that pressure greatly expands the tetragonal magnetic phase, while the stripelike phase shrinks. This reveals that pressure may be a powerful tuning parameter with which to explore the interplay between magnetism and superconductivity in this material