Population-weighted degree-days: The global shift between heating and cooling

Anthropogenic greenhouse gas emissions are driving global increases in temperature. This rise will likely lead to an increase in demand for cooling in the coming years. However, increasing temperatures are not the main explanatory factor for why the world is moving towards more cooling. This paper compares population and area-weighted cooling and heating degree-days derived using ERA5-Land reanalysis temperature, to show that population growth in warmer parts of the world drives cooling demand globally. The analysis shows that mean global area-weighted heating degree-days have fallen 8.46 °C days/year, whereas population-weighted heating degree-days have fallen by 12.5 °C days/year. At the same time, mean global area-weighted cooling degree-days have risen by 3.0 °C days/year, while population-weighted cooling degree-days have risen at 6.0 °C days/year. By using sub-country analysis, this paper shows that population-weighted degree-days can substantially differ from area-weighted degree-days. Finally, the findings highlight that the choice of heating and cooling degree-day base temperature is the most important parameter in the variability of degree-days and will need to be understood better in order to accurately account for future heating and cooling energy demand

Low temperature transport on surface conducting diamond

Magneto-transport measurements were performed on surface conducting hydrogen-terminated diamond (100) hall bars at temperatures between 0.1-5 K in magnetic fields up to 8T.Comment: 2 pages Optoelectronic and Microelectronic Materials & Devices (COMMAD), 2012 Conferenc

How solid is our knowledge of solid walls? - Comparing energy savings through three different methods

Recent UK-based studies have shown a performance gap between the energy performance of buildings calculated using tabulated thermophysical properties of solid walls and that estimated from in-situ measurements. Solid-walled buildings have been targeted by UK Government policies and incentive schemes to meet climate change mitigation targets and improve the efficiency of the building stock, as they are less efficient and more expensive to treat than cavity walls. Since it is common practice to estimate energy use and potential savings for buildings retrofit assuming standard values from the literature, the performance gap may have serious implications on the decision-making and the cost-effectiveness of energy-saving interventions. The aim of this paper is to compare and contrast the results obtained from three different methods for estimating normalised dwelling energy demand: a) the UK energy performance certificate (EPC) method, which uses the standard assessment procedure (SAP) with tabulated inputs (the business as usual case); b) the SAP calculated using empirical air change rates from pressure tests and U-values estimated analysing monitored data with a Bayesian-based dynamic method developed by the authors; c) a normalised annual consumption (NAC) method based on empirical energy consumption data from smart meter and weather data. The analysis is performed on a sample of dwellings from the Energy Saving Trust “Solid Wall Field Trials” dataset. Results show that EPC estimates are systematically higher (between 7.5% and 22.0%) than SAP. Conversely, the NAC displayed a large range of relative differences (between -77% and +99%) compared to the EPC. This raises questions about the relative merits and purpose of the EPC and SAP bottom up methods compared to the smart-meter data-driven NAC method. Further research is suggested using SAP 2009 to isolate the thermal component of energy demand and compare it directly with the NAC component

A note on the universality of the Hagedorn behavior of pp-wave strings

Following on from recent studies of string theory on a one-parameter family of integrable deformations of $AdS_{5}\times S^{5}$ proposed by Lunin and Maldacena, we carry out a systematic analysis of the high temperature properties of type IIB strings on the associated pp-wave geometries. In particular, through the computation of the thermal partition function and free energy we find that not only does the theory exhibit a Hagedorn transition in both the $(J,0,0)$ and $(J,J,J)$ class of pp-waves, but that the Hagedorn temperature is insensitive to the deformation suggesting an interesting universality in the high temperature behaviour of the pp-wave string theory. We comment also on the implications of this universality on the confinement/deconfinement transition in the dual $\mathcal{N}=1$ Leigh-Strassler deformation of ${\cal N}=4$ Yang-Mills theory.Comment: 25 pages; fixed minor typo; added reference

Evidence for localization and 0.7 anomaly in hole quantum point contacts

Quantum point contacts implemented in p-type GaAs/AlGaAs heterostructures are investigated by low-temperature electrical conductance spectroscopy measurements. Besides one-dimensional conductance quantization in units of $2e^{2}/h$ a pronounced extra plateau is found at about $0.7(2e^{2}/h)$ which possesses the characteristic properties of the so-called "0.7 anomaly" known from experiments with n-type samples. The evolution of the 0.7 plateau in high perpendicular magnetic field reveals the existence of a quasi-localized state and supports the explanation of the 0.7 anomaly based on self-consistent charge localization. These observations are robust when lateral electrical fields are applied which shift the relative position of the electron wavefunction in the quantum point contact, testifying to the intrinsic nature of the underlying physics.Comment: 4.2 pages, 3 figure

Implications of the PSR 1257+12 Planetary System for Isolated Millisecond Pulsars

The first extrasolar planets were discovered in 1992 around the millisecond pulsar PSR 1257+12. We show that recent developments in the study of accretion onto magnetized stars, plus the existence of the innermost, moon-sized planet in the PSR 1257+12 system, suggest that the pulsar was born with approximately its current rotation frequency and magnetic moment. If so, this has important implications for the formation and evolution of neutron star magnetic fields as well as for the formation of planets around pulsars. In particular, it suggests that some and perhaps all isolated millisecond pulsars may have been born with high spin rates and low magnetic fields instead of having been recycled by accretion.Comment: 17 pages including one figure, uses aaspp4, accepted by Ap

Beyond the plane-parallel and Newtonian approach: Wide-angle redshift distortions and convergence in general relativity

We extend previous analyses of wide-angle correlations in the galaxy power spectrum in redshift space to include all general relativistic effects. These general relativistic corrections to the standard approach become important on large scales and at high redshifts, and they lead to new terms in the wide-angle correlations. We show that in principle the new terms can produce corrections of nearly 10 % on Gpc scales over the usual Newtonian approximation. General relativistic corrections will be important for future large-volume surveys such as SKA and Euclid, although the problem of cosmic variance will present a challenge in observing this.Comment: 14 pages, 5 figures; Typo in equation 5 corrected; results unaffecte

Herschel Observations of Cataclysmic Variables

We have used the PACS instrument on the Herschel Space Observatory to observe eight cataclysmic variables at 70 and 160 μm. Of these eight objects, only AM Her was detected. We have combined the Herschel results with ground-based, Spitzer, and WISE observations to construct spectral energy distributions for all of the targets. For the two dwarf novae in the sample, SS Cyg and U Gem, we find that their infrared luminosities are completely dominated by their secondary stars. For the two highly magnetic "polars" in our survey, AM Her and EF Eri, we find that their mid-infrared excesses, previously attributed to circumbinary dust emission, can be fully explained by cyclotron emission. The WISE light curves for both sources show large, orbitally modulated variations that are identically phased to their near-IR light curves. We propose that significant emission from the lowest cyclotron harmonics (n ≤ 3) is present in EF Eri and AM Her. Previously, such emission would have been presumed to be optically thick, and not provide significant orbitally modulated flux. This suggests that the accretion onto polars is more complicated than assumed in the simple models developed for these two sources. We develop a model for the near-/mid-IR light curves for WZ Sge with an L2 donor star that shows that the ellipsoidal variations from its secondary star are detected. We conclude that none of the targets surveyed have dusty circumbinary disks

Consistency of the Shannon entropy in quantum experiments

The consistency of the Shannon entropy, when applied to outcomes of quantum experiments, is analysed. It is shown that the Shannon entropy is fully consistent and its properties are never violated in quantum settings, but attention must be paid to logical and experimental contexts. This last remark is shown to apply regardless of the quantum or classical nature of the experiments.Comment: 12 pages, LaTeX2e/REVTeX4. V5: slightly different than the published versio