599 research outputs found

    Active Metamaterials with Negative Static Electric Susceptibility

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    Although well‐established textbook arguments suggest that static electric susceptibility χ(0) must be positive in “all bodies,” it has been pointed out that materials that are not in thermodynamic equilibrium are not necessarily subject to this restriction. Media with inverted populations of atomic and molecular energy levels have been predicted theoretically to exhibit a χ(0) < 0 state, however the systems envisioned require reduced temperature, reduced pressure, and an external pump laser to maintain the population inversion. Further, the existence of χ(0) < 0 has never been confirmed experimentally. Here, a completely different approach is taken to the question of χ(0) < 0 and a design concept to achieve “true” χ(0) < 0 is proposed based on active metamaterials with internal power sources. Two active metamaterial structures are fabricated that, despite still having their power sources implemented externally for reasons of practical convenience, provide evidence in support of the general concept. Effective values are readily achieved at room temperature and pressure and are tunable throughout the range of stability −1 < χ(0) < 0, resulting in experimentally‐determined magnitudes that are over one thousand times greater than those predicted previously. Since χ(0) < 0 is the missing electric analog of diamagnetism, this work opens the door to new technological capabilities such as stable electrostatic levitation

    Severe pulmonary hypertension associated with lung disease is characterised by a loss of small pulmonary vessels on quantitative computed tomography

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    Background: Pulmonary hypertension (PH) in patients with chronic lung disease (CLD) predicts reduced functional status, clinical worsening and increased mortality, with patients with severe PH-CLD (≄35 mmHg) having a significantly worse prognosis than mild to moderate PH-CLD (21-34 mmHg). The aim of this cross-sectional study was to assess the association between computed tomography (CT)-derived quantitative pulmonary vessel volume, PH severity and disease aetiology in CLD. Methods: Treatment-naĂŻve patients with CLD who underwent CT pulmonary angiography, lung function testing and right heart catheterisation were identified from the ASPIRE registry between October 2012 and July 2018. Quantitative assessments of total pulmonary vessel and small pulmonary vessel volume were performed. Results: 90 patients had PH-CLD including 44 associated with COPD/emphysema and 46 with interstitial lung disease (ILD). Patients with severe PH-CLD (n=40) had lower small pulmonary vessel volume compared to patients with mild to moderate PH-CLD (n=50). Patients with PH-ILD had significantly reduced small pulmonary blood vessel volume, compared to PH-COPD/emphysema. Higher mortality was identified in patients with lower small pulmonary vessel volume. Conclusion: Patients with severe PH-CLD, regardless of aetiology, have lower small pulmonary vessel volume compared to patients with mild-moderate PH-CLD, and this is associated with a higher mortality. Whether pulmonary vessel changes quantified by CT are a marker of remodelling of the distal pulmonary vasculature requires further study

    Sexually transmitted infections, including HIV, in the Netherlands in 2013

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    Het aantal mensen dat zich bij een Centrum Seksuele Gezondheid heeft laten testen op een seksueel overdraagbare aandoening (soa) is verder gestegen in 2013. Het percentage mensen met een soa is voor het eerst licht gedaald (met 0,4 procent) sinds 2007. Desondanks blijft dit percentage hoog (14,7 procent). Een goed functionerende soa-monitoring blijft daarom essentieel om zicht te houden op relevante trends, opkomende soa binnen groepen die een grotere kans hebben er een op te lopen, en de effectiviteit van preventieprogramma's. De Centra Seksuele Gezondheid (CSG), voorheen soa-poli's, bieden hoogrisicogroepen de mogelijkheid om zich gratis te laten testen op soa en verstrekken medicatie als er een wordt vastgesteld. Het totaal aantal consulten in 2013 bedroeg 133.585 en is met 10 procent toegenomen ten opzichte van 2012. Van alle bezoekers werden de meeste soa gediagnosticeerd bij mensen die ervoor gewaarschuwd waren dat ze mogelijk een soa hadden opgelopen, mensen jonger dan 25 jaar, migranten uit gebieden waar soa en hiv veel voorkomen (bijvoorbeeld Afrika, Zuid-Amerika of Oost-Europa), of mannen die seks hebben met mannen (MSM). Chlamydia Net als in voorgaande jaren was chlamydia de meest gediagnosticeerde soa bij de CSG in 2013 (15.767 diagnoses). Het percentage mensen dat chlamydia had, daalde licht ten opzichte van 2012 (van 12,2 naar 11,8 procent). Chlamydia werd het meest vastgesteld bij heteroseksuelen, zowel mannen als vrouwen, onder de 25 jaar. Na de uitschieter in 2012 van het aantal en percentage mensen met een agressieve variant van chlamydia, lymphogranuloma venereum, zijn deze cijfers weer afgenomen naar het niveau van de jaren daarvoor (7 procent in 2013). Gonorroe Het percentage personen met een gonorroe-infectie bij de CSG bleef in 2013 stabiel ten opzichte van 2012 (3,6 procent in 2012 en 3,4 procent in 2013), nadat het in de voorgaande jaren licht was gestegen. Deze soa werd het meest gediagnosticeerd bij MSM. Het blijft belangrijk om te volgen of de gonorroe-bacterie resistent raakt tegen de antibiotica die in Nederland voorgeschreven worden, de zogenoemde derde generatie cefalosporines. In diverse Europese landen is deze resistentie waargenomen. Hiv Het aantal personen met een hiv-infectie, gediagnosticeerd bij een van de CSG, is in 2013 gelijk gebleven ten opzichte van 2012 (358 versus 356 in 2012). Het percentage positieve testen daalt sinds 2008: van 3,0 procent naar 1,4 procent bij MSM in 2013. Het percentage mensen dat in een laat stadium van een hiv-infectie bij een hiv-behandelcentrum komt, is de afgelopen jaren gedaald. Het is van belang om tijdig de hiv-diagnose te stellen en zo snel mogelijk de behandeling te starten, omdat hierdoor de gezondheidsschade bij de patiënt verkleind kan worden. Ook neemt door behandeling de besmettelijkheid af, waardoor de kans kleiner is dat hiv wordt overgedragen.In 2013, more people were tested for sexually transmitted infections (STI) at Dutch STI clinics than in previous years. Although the percentage of people with an STI showed a slight decrease (0.4 per cent) for the first time since 2007, it remained high at 14.7 per cent. Effective STI monitoring remains essential for the identification of relevant trends, emerging STIs in high-risk groups, and the effectiveness of prevention programmes. STI clinics offer high-risk groups access to free testing for STI and provide care and treatment if an STI is diagnosed. The total number of consultations in 2013 was 133,585, an increase of 10% compared with 2012. In 2013, STI clinic attendees with an STI were mainly people who reported having been notified of their possible exposure to STI, people aged 20-24, people originating from areas in which STI/HIV is common (e.g. Africa, South America or Eastern Europe), and men who have sex with men (MSM). Chlamydia With 15,767 cases, chlamydia remains the most commonly diagnosed STI in 2013. The percentage of people diagnosed with chlamydia was slightly lower in 2013 than in 2012 (11.8 versus 12.2 respectively). Chlamydia was primarily diagnosed in heterosexuals younger than 25 years old and in both men and women. Following the increase in the number and percentage of lymphogranuloma venereum (LGV; an aggressive variant of chlamydia) infections in 2012, these numbers declined to a level comparable to previous years in 2013. Gonorrhoea Whereas the percentage of people with a gonorrhoea infection slightly had increased in previous years, the percentage remained stable in 2013 (3.4 per cent) compared with 2012 (3.6 per cent). Gonorrhoea was mostly diagnosed in MSM. It remains important to monitor the resistance of the gonorrhoea bacteria against the antibiotic currently recommended in the Netherlands, a third-generation cephalosporin. A rising rate of resistance to this antibiotic has been observed in several European countries. HIVThe number of people diagnosed with HIV at STI clinics in 2013 was similar to that of 2012 (358 versus 356 respectively). Among MSM, the percentage of positive HIV tests decreased from 3.0 per cent in 2008 to 1.4 per cent in 2013. The percentage of HIV-positive people who were diagnosed at a late stage of the infection has decreased in previous years. Early diagnosis and treatment of an HIV infection is important because of individual health benefits and the potential reduction of HIV transmission

    The design of a randomized, placebo-controlled, dose-ranging trial to investigate the efficacy and safety of the ADAMTS-5 inhibitor S201086/GLPG1972 in knee osteoarthritis

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    Objective This study aims to assess the efficacy of the anticatabolic ‘a disintegrin and metalloproteinase with thrombospondin motif-5’ (ADAMTS-5) inhibitor, S201086/GLPG1972, in slowing cartilage loss in participants with knee osteoarthritis (OA). Design ROCCELLA (NCT03595618) is a randomized, double-blind, placebo-controlled, parallel-group, dose-ranging, phase 2 trial. We plan to enrol a total of 852 participants with knee OA across 12 countries. Participants will be randomized 1:1:1:1 to receive 75, 150 or 300 ​mg S201086/GLPG1972, or placebo orally, once daily for 52 weeks. Eligible participants will be aged 40–75 years and have predominantly medial knee OA with centrally read Kellgren–Lawrence grade 2 or 3, OARSI atlas medial femorotibial joint space narrowing grade 1 or 2, and consistent moderate to severe baseline pain. The primary endpoint will be the change from baseline to week 52 in magnetic resonance imaging-assessed central medial femorotibial compartment cartilage thickness. Secondary endpoints will include other structural outcomes, and patient-reported outcomes, as well as safety and pharmacokinetic assessments. Study sites will be assessed for eligibility based on factors including imaging quality, and images will be centrally read and quality checked. Conclusions Using strict inclusion criteria and leading imaging techniques with stringent quality controls, the ROCCELLA trial will evaluate the efficacy of S201086/GLPG1972 in slowing cartilage loss in participants with knee OA. The selected eligibility criteria should enrich for participants with OA who experience sufficient cartilage loss to allow detection of a substantial treatment effect

    Calibration of the Logarithmic-Periodic Dipole Antenna (LPDA) Radio Stations at the Pierre Auger Observatory using an Octocopter

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    An in-situ calibration of a logarithmic periodic dipole antenna with a frequency coverage of 30 MHz to 80 MHz is performed. Such antennas are part of a radio station system used for detection of cosmic ray induced air showers at the Engineering Radio Array of the Pierre Auger Observatory, the so-called Auger Engineering Radio Array (AERA). The directional and frequency characteristics of the broadband antenna are investigated using a remotely piloted aircraft (RPA) carrying a small transmitting antenna. The antenna sensitivity is described by the vector effective length relating the measured voltage with the electric-field components perpendicular to the incoming signal direction. The horizontal and meridional components are determined with an overall uncertainty of 7.4^{+0.9}_{-0.3} % and 10.3^{+2.8}_{-1.7} % respectively. The measurement is used to correct a simulated response of the frequency and directional response of the antenna. In addition, the influence of the ground conductivity and permittivity on the antenna response is simulated. Both have a negligible influence given the ground conditions measured at the detector site. The overall uncertainties of the vector effective length components result in an uncertainty of 8.8^{+2.1}_{-1.3} % in the square root of the energy fluence for incoming signal directions with zenith angles smaller than 60{\deg}.Comment: Published version. Updated online abstract only. Manuscript is unchanged with respect to v2. 39 pages, 15 figures, 2 table

    Multi-resolution anisotropy studies of ultrahigh-energy cosmic rays detected at the Pierre Auger Observatory

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    We report a multi-resolution search for anisotropies in the arrival directions of cosmic rays detected at the Pierre Auger Observatory with local zenith angles up to 80∘80^\circ and energies in excess of 4 EeV (4×10184 \times 10^{18} eV). This search is conducted by measuring the angular power spectrum and performing a needlet wavelet analysis in two independent energy ranges. Both analyses are complementary since the angular power spectrum achieves a better performance in identifying large-scale patterns while the needlet wavelet analysis, considering the parameters used in this work, presents a higher efficiency in detecting smaller-scale anisotropies, potentially providing directional information on any observed anisotropies. No deviation from isotropy is observed on any angular scale in the energy range between 4 and 8 EeV. Above 8 EeV, an indication for a dipole moment is captured; while no other deviation from isotropy is observed for moments beyond the dipole one. The corresponding pp-values obtained after accounting for searches blindly performed at several angular scales, are 1.3×10−51.3 \times 10^{-5} in the case of the angular power spectrum, and 2.5×10−32.5 \times 10^{-3} in the case of the needlet analysis. While these results are consistent with previous reports making use of the same data set, they provide extensions of the previous works through the thorough scans of the angular scales.Comment: Published version. Added journal reference and DOI. Added Report Numbe

    Ultrahigh-energy neutrino follow-up of Gravitational Wave events GW150914 and GW151226 with the Pierre Auger Observatory

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    On September 14, 2015 the Advanced LIGO detectors observed their first gravitational-wave (GW) transient GW150914. This was followed by a second GW event observed on December 26, 2015. Both events were inferred to have arisen from the merger of black holes in binary systems. Such a system may emit neutrinos if there are magnetic fields and disk debris remaining from the formation of the two black holes. With the surface detector array of the Pierre Auger Observatory we can search for neutrinos with energy above 100 PeV from point-like sources across the sky with equatorial declination from about -65 deg. to +60 deg., and in particular from a fraction of the 90% confidence-level (CL) inferred positions in the sky of GW150914 and GW151226. A targeted search for highly-inclined extensive air showers, produced either by interactions of downward-going neutrinos of all flavors in the atmosphere or by the decays of tau leptons originating from tau-neutrino interactions in the Earth's crust (Earth-skimming neutrinos), yielded no candidates in the Auger data collected within ±500\pm 500 s around or 1 day after the coordinated universal time (UTC) of GW150914 and GW151226, as well as in the same search periods relative to the UTC time of the GW candidate event LVT151012. From the non-observation we constrain the amount of energy radiated in ultrahigh-energy neutrinos from such remarkable events.Comment: Published version. Added journal reference and DOI. Added Report Numbe
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