For agriculture, there are three major options for mitigating greenhouse gas (GHG) emissions: 1) productivity improvements, particularly in the livestock sector; 2) dedicated technical mitigation ...measures; and 3) human dietary changes. The aim of the paper is to estimate long-term agricultural GHG emissions, under different mitigation scenarios, and to relate them to the emissions space compatible with the 2 °C temperature target. Our estimates include emissions up to 2070 from agricultural soils, manure management, enteric fermentation and paddy rice fields, and are based on IPCC Tier 2 methodology. We find that baseline agricultural CO
2
-equivalent emissions (using Global Warming Potentials with a 100 year time horizon) will be approximately 13 Gton CO
2
eq/year in 2070, compared to 7.1 Gton CO
2
eq/year 2000. However, if faster growth in livestock productivity is combined with dedicated technical mitigation measures, emissions may be kept to 7.7 Gton CO
2
eq/year in 2070. If structural changes in human diets are included, emissions may be reduced further, to 3–5 Gton CO
2
eq/year in 2070. The total annual emissions for meeting the 2 °C target with a chance above 50 % is in the order of 13 Gton CO
2
eq/year or less in 2070, for all sectors combined. We conclude that reduced ruminant meat and dairy consumption will be indispensable for reaching the 2 °C target with a high probability, unless unprecedented advances in technology take place.
One of the most surprising predictions of modern quantum theory is that the vacuum of space is not empty. In fact, quantum theory predicts that it teems with virtual particles flitting in and out of ...existence. Although initially a curiosity, it was quickly realized that these vacuum fluctuations had measurable consequences--for instance, producing the Lamb shift of atomic spectra and modifying the magnetic moment of the electron. This type of renormalization due to vacuum fluctuations is now central to our understanding of nature. However, these effects provide indirect evidence for the existence of vacuum fluctuations. From early on, it was discussed whether it might be possible to more directly observe the virtual particles that compose the quantum vacuum. Forty years ago, it was suggested that a mirror undergoing relativistic motion could convert virtual photons into directly observable real photons. The phenomenon, later termed the dynamical Casimir effect, has not been demonstrated previously. Here we observe the dynamical Casimir effect in a superconducting circuit consisting of a coplanar transmission line with a tunable electrical length. The rate of change of the electrical length can be made very fast (a substantial fraction of the speed of light) by modulating the inductance of a superconducting quantum interference device at high frequencies (>10 gigahertz). In addition to observing the creation of real photons, we detect two-mode squeezing in the emitted radiation, which is a signature of the quantum character of the generation process.
Only 70-80% of patients with chronic inflammatory demyelinating polyneuropathy (CIDP) respond satisfactorily to the established first-line immunomodulatory treatments. Autologous haematopoietic stem ...cell transplantation (AHSCT) has been performed as a last treatment resort in a few therapy-refractory cases with CIDP. We describe the results of AHSCT in 11 consecutive Swedish patients with therapy-refractory CIDP with a median follow-up time of 28 months.
Case data were gathered retrospectively for AHSCT treatments in 11 patients with CIDP refractory to the first-line immunomodulatory treatments, intravenous high-dose immunoglobulin, corticosteroids and plasma exchange and to one or more second-line treatments used in 10 of the 11 patients.
The median Inflammatory Neuropathy Cause and Treatment (INCAT) score within 1 month prior to AHSCT was 6 and the Rankin score 4. Total INCAT and Rankin scores improved significantly within 2-6 months after AHSCT and continued to do so at last follow-up. The motor action potential amplitudes (CMAP) improved already within 4 months (median) after AHSCT. Three of the 11 patients relapsed during the follow-up period, requiring retransplantation with AHSCT in one. Eight of the 11 patients maintained drug-free remission upon last follow-up. AHSCT was safe but on the short term associated with a risk of cytomegalovirus (CMV) and Epstein-Barr virus reactivation, CMV disease, haemorrhagic cystitis and pancreatitis.
Our results though hampered by the limited number of patients and the lack of a control group suggest AHSCT to be efficacious in therapy-refractory CIDP, with a manageable complication profile. Confirmation of these results is necessary through randomised controlled trials.
Here, a lead‐free silver bismuth iodide (AgI/BiI3) with a crystal structure with space group R3‾
m is investigated for use in solar cells. Devices based on the silver bismuth iodide deposited from ...solution on top of TiO2 and the conducting polymer poly(3‐hexylthiophene‐2,5‐diyl) (P3HT) as a hole‐transport layer are prepared and the photovoltaic performance is very promising with a power conversion efficiency over 2 %, which is higher than the performance of previously reported bismuth‐halide materials for solar cells. Photocurrent generation is observed between 350 and 700 nm, and the maximum external quantum efficiency is around 45 %. The results are compared to solar cells based on the previously reported material AgBi2I7, and we observe a clearly higher performance for the devices with the new silver and bismuth iodides composition and different crystal structure. The X‐ray diffraction spectrum of the most efficient silver bismuth iodide material shows a hexagonal crystal structure with space group R3‾
m, and from the light absorption spectrum we obtain an indirect band gap energy of 1.62 eV and a direct band gap energy of 1.85 eV. This report shows the possibility for finding new structures of metal‐halides efficient in solar cells and points out new directions for further exploration of lead‐free metal‐halide solar cells.
Minus the lead: Devices based on silver bismuth iodide deposited from solution on top of TiO2 and the conducting polymer poly(3‐hexylthiophene‐2,5‐diyl) (P3HT) as a hole‐transport layer are prepared and the photovoltaic performance is very promising with a power conversion efficiency over 2 %.
We investigate the nonlinear interaction between a squeezed cavity mode and a mechanical mode in an optomechanical system (OMS) that allows us to selectively obtain either a radiation-pressure ...coupling or a parametric-amplification process. The squeezing of the cavity mode can enhance the interaction strength into the single-photon strong-coupling regime, even when the OMS is originally in the weak-coupling regime. Moreover, the noise of the squeezed mode can be suppressed completely by introducing a broadband-squeezed vacuum environment that is phase matched with the parametric amplification that squeezes the cavity mode. This proposal offers an alternative approach to control the OMS using a squeezed cavity mode, which should allow single-photon quantum processes to be implemented with currently available optomechanical technology. Potential applications range from engineering single-photon sources to nonclassical phonon states.
We present version 2 of QuTiP, the Quantum Toolbox in Python. Compared to the preceding version J.R. Johansson, P.D. Nation, F. Nori, Comput. Phys. Commun. 183 (2012) 1760., we have introduced ...numerous new features, enhanced performance, and made changes in the Application Programming Interface (API) for improved functionality and consistency within the package, as well as increased compatibility with existing conventions used in other scientific software packages for Python. The most significant new features include efficient solvers for arbitrary time-dependent Hamiltonians and collapse operators, support for the Floquet formalism, and new solvers for Bloch–Redfield and Floquet–Markov master equations. Here we introduce these new features, demonstrate their use, and give a summary of the important backward-incompatible API changes introduced in this version.
Program title: QuTiP: The Quantum Toolbox in Python
Catalog identifier: AEMB_v2_0
Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEMB_v2_0.html
Program obtainable from: CPC Program Library, Queen’s University, Belfast, N. Ireland
Licensing provisions: GNU General Public License, version 3
No. of lines in distributed program, including test data, etc.: 33625
No. of bytes in distributed program, including test data, etc.: 410064
Distribution format: tar.gz
Programming language: Python.
Computer: i386, x86-64.
Operating system: Linux, Mac OSX.
RAM: 2+ Gigabytes
Classification: 7.
External routines: NumPy, SciPy, Matplotlib, Cython
Catalog identifier of previous version: AEMB_v1_0
Journal reference of previous version: Comput. Phys. Comm. 183 (2012) 1760
Does the new version supercede the previous version?: Yes
Nature of problem: Dynamics of open quantum systems
Solution method: Numerical solutions to Lindblad, Floquet–Markov, and Bloch–Redfield master equations, as well as the Monte Carlo wave function method.
Reasons for new version: Compared to the preceding version we have introduced numerous new features, enhanced performance, and made changes in the Application Programming Interface (API) for improved functionality and consistency within the package, as well as increased compatibility with existing conventions used in other scientific software packages for Python. The most significant new features include efficient solvers for arbitrary time-dependent Hamiltonians and collapse operators, support for the Floquet formalism, and new solvers for Bloch–Redfield and Floquet–Markov master equations.
Restrictions: Problems must meet the criteria for using the master equation in Lindblad, Floquet–Markov, or Bloch–Redfield form.
Running time: A few seconds up to several tens of hours, depending on size of the underlying Hilbert space.
The hole transporting material (HTM) is an essential component in perovskite solar cells (PSCs) for efficient extraction and collection of the photoinduced charges. Triphenylamine- and ...carbazole-based derivatives have extensively been explored as alternative and economical HTMs for PSCs. However, the improvement of their power conversion efficiency (PCE), as well as further investigation of the relationship between the chemical structure of the HTMs and the photovoltaic performance, is imperatively needed. In this respect, a simple carbazole-based HTM X25 was designed on the basis of a reference HTM, triphenylamine-based X2, by simply linking two neighboring phenyl groups in a triphenylamine unit through a carbon–carbon single bond. It was found that a lowered highest occupied molecular orbital (HOMO) energy level was obtained for X25 compared to that of X2. Besides, the carbazole moiety in X25 improved the molecular planarity as well as conductivity property in comparison with the triphenylamine unit in X2. Utilizing the HTM X25 in a solar cell with mixed-ion perovskite HC(NH2)20.85(CH3NH3)0.15Pb(I0.85Br0.15)3, a highest reported PCE of 17.4% at 1 sun (18.9% under 0.46 sun) for carbazole-based HTM in PSCs was achieved, in comparison of a PCE of 14.7% for triphenylamine-based HTM X2. From the steady-state photoluminescence and transient photocurrent/photovoltage measurements, we conclude that (1) the lowered HOMO level for X25 compared to X2 favored a higher open-circuit voltage (V oc) in PSCs; (2) a more uniform formation of X25 capping layer than X2 on the surface of perovskite resulted in more efficient hole transport and charge extraction in the devices. In addition, the long-term stability of PSCs with X25 is significantly enhanced compared to X2 due to its good uniformity of HTM layer and thus complete coverage on the perovskite. The results provide important information to further develop simple and efficient small molecular HTMs applied in solar cells.
We investigate the dynamical Casimir effect in a coplanar waveguide (CPW) terminated by a superconducting quantum interference device (SQUID). Changing the magnetic flux through the SQUID ...parametrically modulates the boundary condition of the CPW, and thereby, its effective length. Effective boundary velocities comparable to the speed of light in the CPW result in broadband photon generation which is identical to the one calculated in the dynamical Casimir effect for a single oscillating mirror. We estimate the power of the radiation for realistic parameters and show that it is experimentally feasible to directly detect this nonclassical broadband radiation.
We compare the technique of using the orbital angular momentum (OAM) of radio waves for generating multiple channels in a radio communication scenario with traditional multiple-in-multiple-out (MIMO) ...communication methods. We demonstrate that, for certain array configurations in free space, traditional MIMO theory leads to eigen-modes identical to the OAM states. From this we conclude that communicating over the sub-channels given by OAM states is a subset of the solutions offered by MIMO, and therefore does not offer any additional gains in capacity.
Lead halide perovskite solar cells have significantly increased in both efficiency and stability over the last decade. An important aspect of their long-term stability is the reaction between the ...perovskite and other materials in the solar cell. This includes the contact materials and their degradation if they can potentially come into contact through, e.g., pinholes or material diffusion and migration. Here, we explore the interactions of silver contacts with lead halide perovskites of different compositions by using a model system where thermally evaporated silver was deposited directly on the surface of the perovskites. Using X-ray photoelectron spectroscopy with support from scanning electron microscopy, X-ray diffraction, and UV–visible absorption spectroscopy, we studied the film formation and degradation of silver on perovskites with different compositions. The deposited silver does not form a continuous silver film but instead tends to form particles on a bare perovskite surface. These particles are initially metallic in character but degrade into AgI and AgBr over time. The degradation and migration appear unaffected by the replacement of methylammonium with cesium but are significantly slowed down by the complete replacement of iodide with bromide. The direct contact between silver and the perovskite also significantly accelerates the degradation of the perovskite, with a significant loss of organic cations and the possible formation of PbO, and, at the same time, changed the surface morphology of the iodide-rich perovskite interface. Our results further indicate that an important degradation pathway occurred through gas-phase perovskite degradation products. This highlights the importance of control over the interface materials and the use of completely hermetical barrier layers for the long-term stability and therefore the commercial viability of silver electrodes.
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