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.

Fatigue and cognitive function in systemic lupus erythematosus: associations with white matter microstructural damage. A diffusion tensor MRI study and meta-analysis.

Objective The objective of this study was to investigate fatigue and cognitive impairments in systemic lupus erythematous (SLE) in relation to diffuse white matter microstructural brain damage. Methods Diffusion tensor MRI, used to generate biomarkers of brain white matter microstructural integrity, was obtained in patients with SLE and age-matched controls. Fatigue and cognitive function were assessed and related to SLE activity, clinical data and plasma biomarkers of inflammation and endothelial dysfunction. Results Fifty-one patients with SLE (mean age 48.8 ± 14.3 years) were included. Mean diffusivity (MD) was significantly higher in all white matter fibre tracts in SLE patients versus age-matched healthy controls ( p < 0.0001). Fatigue in SLE was higher than a normal reference range ( p < 0.0001) and associated with lower MD ( ß = -0.61, p = 0.02), depression ( ß = 0.17, p = 0.001), anxiety ( ß = 0.13, p = 0.006) and higher body mass index ( ß = 0.10, p = 0.004) in adjusted analyses. Poorer cognitive function was associated with longer SLE disease duration ( p = 0.003) and higher MD ( p = 0.03) and, in adjusted analysis, higher levels of IL-6 ( ß = -0.15, p = 0.02) but not with MD. Meta-analysis (10 studies, n = 261, including the present study) confirmed that patients with SLE have higher MD than controls. Conclusion Patients with SLE have more microstructural brain white matter damage for age than the general population, but this does not explain increased fatigue or lower cognition in SLE. The association between raised IL-6 and worse current cognitive function in SLE should be explored in larger datasets.

Dispersion Effects on the Thermodynamics and Transition States of Dimethylarsinic Acid Adsorption on Hydrated Iron (Oxyhydr)oxide Clusters from Density Functional Theory Calculations.

Reaction pathway information and transition states are crucial for understanding adsorption mechanisms of pollutants, such as dimethylarsinic acid (DMA), at the liquid-solid interface. We report a detailed computational analysis of the complexes of DMA on iron (oxyhydr)oxides, including activation energies, transition states, Gibbs free energies of adsorption, Mulliken charges, charge redistribution upon adsorption, and stretching frequencies of As-O bonds for comparison with experimental spectroscopic data. Calculations were performed using density functional theory (DFT) at the B3LYP/6-311+G(d,p) level using both implicit and explicit hydration. For comparison, calculations were also performed for arsenate. Dispersion corrections were included since experimental data showed that DMA forms mostly outer-sphere complexes. Calculated electronic energies indicate that dispersion corrections are important when dealing with outer-sphere complexes, and that there is a high activation barrier of ca. 43 kJ mol-1 to transition from mono- to bidentate DMA complexes. Additionally, extending the modeled iron (oxyhydr)oxides surface to include four Fe centers and analyzing the charge distribution upon adsorption of DMA reveals that electrostatics play a role in the transition from outer-sphere to monodentate complexes. The significance of our results for the overall surface complexation mechanism of DMA and arsenate is discussed.

The influence of status and the social environment on energy stores in a social fish.

This study explores how muscle and liver energy stores are linked with social status and the social environment in Neolamprologus pulcher, a cooperatively breeding fish that lives in colonies comprised of up to 200 distinct social groups. Subordinate muscle energy stores were positively correlated with the number of neighbouring social groups in the colony, but this pattern was not observed in dominant N. pulcher. Furthermore, liver energy stores were smaller in dominants living at the edge of the colony compared with those living in the colony centre, with no differences among subordinates in liver energy stores. Subordinate N. pulcher may build up large energy stores in the muscles to fuel rapid growth after dispersal, which could occur more frequently in high-density environments. Dominant N. pulcher may use the more easily mobilized energy stores in the liver to fuel daily activities, which could be more energetically demanding on the edge of the colony as a result of the increased predation defence needed on the edge. Overall, this study demonstrates that both subordinate and dominant physiology in N. pulcher varies with characteristics of the social environment. Furthermore, dominant and subordinate energy storage strategies appear to differ due to status-dependent variation in daily activities and variation in the need to prepare for future reproductive or dispersal opportunities.

The modifying effect of the building envelope on population exposure to PM2.5 from outdoor sources.

UNLABELLED: A number of studies have estimated population exposure to PM2.5 by examining modeled or measured outdoor PM2.5 levels. However, few have taken into account the mediating effects of building characteristics on the ingress of PM2.5 from outdoor sources and its impact on population exposure in the indoor domestic environment. This study describes how building simulation can be used to determine the indoor concentration of outdoor-sourced pollution for different housing typologies and how the results can be mapped using building stock models and Geographical Information Systems software to demonstrate the modifying effect of dwellings on occupant exposure to PM2.5 across London. Building archetypes broadly representative of those in the Greater London Authority were simulated for pollution infiltration using EnergyPlus. In addition, the influence of occupant behavior on indoor levels of PM2.5 from outdoor sources was examined using a temperature-dependent window-opening scenario. Results demonstrate a range of I/O ratios of PM2.5 , with detached and semi-detached dwellings most vulnerable to high levels of infiltration. When the results are mapped, central London shows lower I/O ratios of PM2.5 compared with outer London, an apparent inversion of exposure most likely caused by the prevalence of flats rather than detached or semi-detached properties. PRACTICAL IMPLICATIONS: Population exposure to air pollution is typically evaluated using the outdoor concentration of pollutants and does not account for the fact that people in London spend over 80% of their time indoors. In this article, building simulation is used to model the infiltration of outdoor PM2.5 into the domestic indoor environment for dwellings in a London building stock model, and the results mapped. The results show the variation in relative vulnerability of dwellings to pollution infiltration, as well as an estimated absolute indoor concentration across the Greater London Authority (GLA) scaled by local outdoor levels. The practical application of this work is a better understanding of the modifying effect of the building geometry and envelope design on pollution exposure, and how the London building stock may alter exposure. The results will be used to inform population exposure to PM2.5 in future environmental epidemiological studies.

Conserving large populations of lions - the argument for fences has holes.

Packer et al. reported that fenced lion populations attain densities closer to carrying capacity than unfenced populations. However, fenced populations are often maintained above carrying capacity, and most are small. Many more lions are conserved per dollar invested in unfenced ecosystems, which avoid the ecological and economic costs of fencing.

Variation in social information use: the influences of information reliability and mass on decision making in a group-living fish Gambusia affinis.

The effect of the reliability of available social information was assessed by examining whether the age of social information changes its effects on a foraging decision in a group-living fish Gambusia affinis. Individuals switched their patch preference when faced with social information that conflicted with personal information in general; the age of the social information, however, did not significantly influence preference for feeding patch. The mass of decision makers was positively correlated with their use of available social information, with heavier individuals exhibiting a greater difference in patch preference than lighter individuals, suggesting that large and small G. affinis trade-off the benefits of information acquisition and the costs of competition from conspecifics differently.

Social support correlates with glucocorticoid concentrations in wild African elephant orphans.

Social relationships have physiological impacts. Here, we investigate whether loss of the mother/offspring relationship has lasting effects on fecal glucocorticoid metabolite (fGCM) concentrations in wild African elephant orphans several years following their mothers' deaths. We find no difference in fGCM concentrations between orphans and nonorphans, but find lower fGCM concentrations in elephants with more age mates in their family. We also unexpectedly identify lower concentrations in orphans without their natal family versus nonorphans and natal orphans, which we speculate may be due to the development of hypocortisolism following a prolonged period without familial support. An index of plant productivity (i.e. food) shows the largest correlation with fGCM concentrations. Our findings indicate no lasting differences in glucocorticoid concentrations of surviving orphan elephants who are with their family, suggest the presence of age mates may reduce glucocorticoid concentrations in elephants, and emphasize that basic survival needs are the primary regulators of the stress response.

Thermodynamics of dimethylarsinic acid and arsenate interactions with hydrated iron-(oxyhydr)oxide clusters: DFT calculations.

Dimethylarsinic Acid (DMA) belongs to an important class of organoarsenical compounds commonly detected in arsenic speciation studies of environmental samples and pyrolysis products of fossil fuels. Transformation of DMA under certain conditions leads to the formation of other forms of arsenic, which could be more toxic than DMA to biota, and more efficient in deactivating catalysts used in petrochemical refining. Published surface sensitive X-ray and infrared spectroscopic work suggested that DMA simultaneously forms inner- and outer-sphere complexes with iron-(oxyhydr)oxides. Computational work on the complexation of arsenicals with various surfaces of environmental and industrial interest provides useful information that aids in the interpretation of experimental spectroscopic data as well as predictions of thermodynamic favorability of surface interactions. We report herein Gibbs free energies of adsorption, ΔG(ads), for various ligand exchange reactions between hydrated complexes of DMA and Fe-(oxyhydr)oxide clusters calculated using density functional theory (DFT) at the B3LYP/6-311+G(d,p) level. Calculations using arsenate were also performed for comparison. Calculated As-(O,Fe) distances and stretching frequencies of As-O bonds are also reported for comparison with experimental spectroscopic data. Gibbs free energies of desorption, ΔG(des), due to reactions with phosphorus species at pH 7 are reported as well. Our results indicate that the formation of both inner- and outer-sphere DMA complexes is thermodynamically favorable, with the former having a more negative ΔG(ads). Values of ΔG(des) indicate that desorption favorability of DMA complexes increases in this order: bidentate < mondentate < outersphere. The significance of our results for the overall surface complexation mechanism of DMA is discussed.

Relativistic-consistent electron densities of the coinage metal clusters M2, M4, M4(2-), and M4Na2 (M = Cu, Ag, Au): a QTAIM study.

We employ second-order Møller-Plesset perturbation theory level in combination with recently developed pseudopotential-based correlation consistent basis sets to obtain accurate relativistic-consistent electron densities for small coinage metal clusters. Using calculated electron densities, we employ Bader's quantum theory of atoms in molecules (QTAIM) to gain insights into the nature of metal-metal bonding in the clusters M(2), M(4), M(4)(2-), and M(4)Na(2) (M = Cu, Ag, Au). For the simplest case of the metal dimer, M(2), we correlate the strength of the metal-metal bond with the value of the electron density at the bond critical point, the total energy density at the bond critical point, the sharing (delocalization) index, and the values of the two principle negative curvatures. We then consider changes to the metal-metal bonding and charge density distribution upon the addition of two metal atoms to form the metal tetramer, M(4), and then followed by the addition of an electron pair to form M(4)(2-) and finally followed by the addition of two alkali metal (sodium) ions to form M(4)Na(2). Using topological properties of the electron density, we present evidence for the existence of σ-aromaticity in Au(4)(2-). We also report the existence of two non-nuclear attractors in the molecular graph of Cu(4)(2-) and large negative charge accumulation in the nonbonded Cu basins of this cluster.

Insights into the surface complexation of dimethylarsinic acid on iron (oxyhydr)oxides from ATR-FTIR studies and quantum chemical calculations.

The surface chemistry of methylated arsenicals with ubiquitous geosorbents and industrial catalysts is poorly understood. These arsenic compounds pose both a health and an environmental risk in addition to being a challenge to the energy industry. We report herein a detailed spectroscopic analysis of the surface structure of dimethylarsinic acid (DMA) adsorbed on hematite and goethite using attenuated total internal reflectance Fourier transform infrared spectroscopy (ATR-FTIR). Spectra of adsorbed DMA, DMA(ads), were collected in situ as a function of pH and ionic strength, using both H(2)O and D(2)O at 298 K in flow mode. Experimental data were complemented with DFT calculations of geometries and frequencies of hydrated DMA-iron oxide clusters. Results indicate the simultaneous formation of inner- and outer-sphere complexes with distinct spectral components. Desorption behavior of DMA due to chloride and phosphate was studied as a function of time from the decrease in the absorbance of apparent spectral features. The impact of our studies on the environmental fate of DMA in geochemical environments and the design of technologies to reduce arsenic content in fuels are discussed.

Experimental and theoretical study on activation of the C-H bond in pyridine by [M(m)]- (M = Cu, Ag, Au, m = 1-3).

Activation of the C-H bond of pyridine by [M(m)](-) (M = Cu, Ag, Au, m = 1-3) is investigated by experiment and theory. Complexes of coinage metal clusters and the pyridyl group, [M(m)-C(5)H(4)N](-), are produced from reactions between metal clusters formed by laser ablation of coinage metal samples and pyridine molecules seeded in argon carrier gas. We examine the structure and formation mechanism of these pyridyl-coinage metal complexes. Our study shows that C(5)H(4)N bonds to the metal clusters through a M-C sigma bond and [M(m)-C(5)H(4)N](-) is produced via a stepwise mechanism. The first step is a direct insertion reaction between [M(m)](-) and C(5)H(5)N with activation of the C-H bond to yield the intermediate [HM(m)-C(5)H(4)N](-). The second step is H atom abstraction by a neutral metal atom to yield [M(m)-C(5)H(4)N](-).

Interacting electrons, spin statistics, and information theory.

We consider a nearly (or quasi) uniform gas of interacting electrons for which spin statistics play a crucial role. A previously developed procedure, based on the extension of the Levy-Lieb constrained search principle and Monte Carlo sampling of electron configurations in space, allows us to approximate the form of the kinetic-energy functional. For a spinless electron gas, this procedure led to a correlation term, which had the form of the Shannon entropy, but the resulting kinetic-energy functional does not satisfy the Lieb-Thirring inequality, which is rigorous and one of the most general relations regarding the kinetic energy. In this paper, we show that when the fermionic character of the electrons is included via a statistical spin approach, our procedure leads to correlation terms, which also have the form of the Shannon entropy and the resulting kinetic-energy functional does satisfy the Lieb-Thirring inequality. In this way we further strengthen the connection between Shannon entropy and electron correlation and, more generally, between information theory and quantum mechanics.

Effective population size dynamics reveal impacts of historic climatic events and recent anthropogenic pressure in African elephants.

Two hundred years of elephant hunting for ivory, peaking in 1970-1980s, caused local extirpations and massive population declines across Africa. The resulting genetic impacts on surviving populations have not been studied, despite the importance of understanding the evolutionary repercussions of such human-mediated events on this keystone species. Using Bayesian coalescent-based genetic methods to evaluate time-specific changes in effective population size, we analysed genetic variation in 20 highly polymorphic microsatellite loci from 400 elephants inhabiting the greater Samburu-Laikipia region of northern Kenya. This area experienced a decline of between 80% and 90% in the last few decades when ivory harvesting was rampant. The most significant change in effective population size, however, occurred approximately 2500 years ago during a mid-Holocene period of climatic drying in tropical Africa. Contrary to expectations, detailed analyses of four contemporary age-based cohorts showed that the peak poaching epidemic in the 1970s caused detectable temporary genetic impacts, with genetic diversity rebounding as juveniles surviving the poaching era became reproductively mature. This study demonstrates the importance of climatic history in shaping the distribution and genetic history of a keystone species and highlights the utility of coalescent-based demographic approaches in unravelling ancestral demographic events despite a lack of ancient samples. Unique insights into the genetic signature of mid-Holocene climatic change in Africa and effects of recent poaching pressure on elephants are discussed.

A series of intrinsically chiral gold nanocage structures.

We present a series of intrinsically chiral gold nanocage structures, Au9n+6, which are stable for n ≥ 2. These structures consist of an Au9n tube which is capped with Au3 units at each end. Removing the Au3 caps, we obtain a series of intrinsically chiral gold nanotube structures, Au9n, which are stable for n ≥ 4. The intrinsic chirality of these structures results from the helicity of the gold strands which form the tube and not because an individual Au atom is a chiral center. The symmetry of these structures is C3 and substructures of gold hexagons with a gold atom in the middle are particularly prominent. We focus on the properties of Au42 (C3) and Au105 (C3) which are the two smallest gold nanocage structures to be completely tiled by these Au7 "golden-eye" substructures. Our main focus is on Au42 (C3) since gold clusters in the 40-50 atom regime are currently being investigated in gas phase experiments. We show that the intrinsically chiral Au42 cage structure is energetically comparable with previously reported achiral cage and compact Au42 structures. Cage structures are of particular interest because species can be encapsulated (and stabilized) inside the cage and we provide strong evidence that Au6@Au42 (C3) is the global minimum Au48 structure. The intrinsically chiral gold nanocage structures, which exhibit a range of size-related properties, have potential applications in chiral catalysis and as components in nanostructured devices.

Hip joint range of motion reduction in sports-related chronic groin injury diagnosed as pubic bone stress injury.

Traumatic osteitis pubis is a non-specific entity that relates to chronic groin injury and has recently been described as being akin to a pubic bone stress injury. It is uncertain whether or not reduction of hip joint range of motion occurs in traumatic osteitis pubis. The purpose of this study was to establish whether there is a reduction of hip range of motion in athletes who have chronic groin injury diagnosed as pubic bone stress injury. A case-control study was performed whereby 89 Australian Rules footballers underwent, with clinical history unknown, clinical and MRI examination of the groin region. Clinical criteria (pain with tenderness) and MR-criteria (pubic bone marrow oedema) were used for diagnosis of pubic bone stress injury. End-range internal and external rotation hip motion was measured using a goniometer. Athletes with and without symptoms were compared, as were athletes with current symptoms with athletes who had recovered from their groin pain episode. Chronic groin injury was diagnosed in 47 athletes with 37 having pubic bone stress injury. Thirteen athletes had previous groin injury. A reduction of internal and external hip range of motion was demonstrated in athletes with pubic bone stress injury (p < 0.05) and in athletes who had current symptoms compared to those who had recovered from their groin pain episode (p < 0.05). A reduction in hip range of motion was evident in athletes with chronic groin injury diagnosed as pubic bone stress injury. There may be a role for increasing hip range of motion in rehabilitation.

The impact of assertive outreach teams on hospital admissions for psychosis: a time series analysis.

Although the assertive outreach model was developed in the United States and imported to the United Kingdom to date, there is only limited evidence to support its wide-scale implementation within the United Kingdom. This is the first study to have combined a large dataset with this type of research method to explore the impact of assertive outreach teams on hospital admissions. The introduction and expansion of assertive outreach teams was associated with reducing hospital admissions for people with psychosis. This study found a consistent summer peak in hospital admissions which community and in-patient mental health nurses should take account of and plan for. Ever since the Mental Health Policy Implementation Policy Guide paved the way for the introduction of the Assertive Outreach Treatment (AOT) model in England, the impact of this approach has been the subject of considerable debate but limited evaluation. To date, most of the evidence supporting this model has originated from outside the United Kingdom. A central aim of the AOT was to reduce the need for in-patient treatment. We aimed to assess the impact of the AOT model on hospital admissions for people with psychosis in England. Interrupted time series analysis was used in this study to evaluate the impact of the policy change. Following the introduction of the AOT model, a statistically significant reduction in hospital admissions for psychosis was found. In addition, we observed a repeated, annual summer peak in admissions. This study adds to the international evidence which supports the effectiveness of the AOT model in reducing hospital admissions for people with severe mental health problems. We offer five suggested implications for mental health nurses and clients based on our findings.

The effects of temporal variation in predation risk on anti-predator behaviour: an empirical test using marine snails.

Foraging animals must often balance the conflicting demands of finding food and avoiding predators. Temporal variation in predation risk is expected to influence how animals allocate time to these behaviours. Counterintuitively, the proportion of time spent foraging during both high- and low-risk periods should increase with increasing time exposed to high risk. We tested this prediction using intertidal marine snails (Littorina spp.) that were exposed to temporal variation in perceived predation risk from crabs (Cancer productus and Cancer magister). Our results were consistent with those predicted for high-risk, but not low-risk, periods. During high-risk periods, a greater number of snails foraged (versus those that left the water or remained in their shells) as time at high perceived risk increased. For low-risk periods, there was no relationship between the number of snails foraging and time at high risk. This might be due to snails in all treatments foraging maximally in the low-risk periods. As a consequence, the difference in the number of snails foraging between high- and low-risk periods decreased with increasing time subject to high risk. These results indicate that the commonly used protocol of exposing foragers to a single pulse of heightened risk might tend to overestimate their typical investment in anti-predator behaviour.

Acid tolerance response of biofilm cells of Streptococcus mutans.

Streptococcus mutans, a major etiological agent of dental caries, is a component of the dental plaque biofilm and functions during caries progression in acidic lesions that may be at or below pH 4. In this study, we were interested in determining the acid tolerance of 1-7-day chemostat-grown biofilm cells of S. mutans BM71 growing in a semi-defined medium at a rate consistent with that of cells in dental plaque (dilution rate=0.1 h(-1)), as well as, assessing the capacity of 2- and 5-day biofilms to induce an acid tolerance response that would enhance survival at a killing pH (3.5). As expected, biofilm cell growth increased (2.5-fold) from day 1 to day 7 (10.6-25.7 x 10(6) cells cm(-)(2)) with the percentage live cells over that period averaging 79.4%, slightly higher than that of planktonic cells (77.4%). Biofilms were highly resistant to acid killing at pH 3.5 for 2 h with survival ranging from 41.8 (1 day) to 63.9% (7 day), while the percentage of live cells averaged 43.4%. Planktonic and dispersed biofilm cells were very acid-sensitive with only 0.0009%- and 0.0002-0.2% survivors, respectively. Unlike the planktonic cells, the incubation of 2- and 5-day biofilms at pH 5.5 for periods of up to 6 h induced strong acid tolerance responses that enhanced survival during a subsequent exposure to acid killing at pH 3.5.

Protein expression by planktonic and biofilm cells of Streptococcus mutans.

Streptococcus mutans, a major causal agent of dental caries, functions in nature as a component of a biofilm on teeth (dental plaque) and yet very little information is available on the physiology of the organism in such surface-associated communities. As a consequence, we undertook to examine the synthesis of proteins by planktonic and biofilm cells growing in a biofilm chemostat at pH 7.5 at a dilution rate of 0.1 h(-1) (mean generation time=7 h). Cells were incubated with (14)C-labelled amino acids, the proteins extracted and separated by two-dimensional electrophoresis followed by autoradiography and computer-assisted image analysis. Of 694 proteins analysed, 57 proteins were enhanced 1.3-fold or greater in biofilm cells compared to planktonic cells with 13 only expressed in sessile cells. Diminished protein expression was observed with 78 proteins, nine of which were not expressed in biofilm cells. The identification of enhanced and diminished proteins by mass spectrometry and computer-assisted protein sequence analysis revealed that, in general, glycolytic enzymes involved in acid formation were repressed in biofilm cells, while biosynthetic processes were enhanced. The results show that biofilm cells possess novel proteins, of as yet unknown function, that are not present in planktonic cells.