Towards a science of climate and energy choices

The linked problems of energy sustainability and climate change are among the most complex and daunting facing humanity at the start of the twenty-first century. This joint Nature Energy and Nature Climate Change Collection illustrates how understanding and addressing these problems will require an integrated science of coupled human and natural systems; including technological systems, but also extending well beyond the domain of engineering or even economics. It demonstrates the value of replacing the stylized assumptions about human behaviour that are common in policy analysis, with ones based on data-driven science. We draw from and engage articles in the Collection to identify key contributions to understanding non-technological factors connecting economic activity and greenhouse gas emissions, describe a multi-dimensional space of human action on climate and energy issues, and illustrate key themes, dimensions and contributions towards fundamental understanding and informed decision making

Sympatric woodland Myotis bats form tight-knit social groups with exclusive roost home ranges

Background: The structuring of wild animal populations can influence population dynamics, disease spread, and information transfer. Social network analysis potentially offers insights into these processes but is rarely, if ever, used to investigate more than one species in a community. We therefore compared the social, temporal and spatial networks of sympatric Myotis bats (M. nattereri (Natterer's bats) and M. daubentonii (Daubenton's bats)), and asked: (1) are there long-lasting social associations within species? (2) do the ranges occupied by roosting social groups overlap within or between species? (3) are M. daubentonii bachelor colonies excluded from roosting in areas used by maternity groups? Results: Using data on 490 ringed M. nattereri and 978 M. daubentonii from 379 colonies, we found that both species formed stable social groups encompassing multiple colonies. M. nattereri formed 11 mixed-sex social groups with few (4.3%) inter-group associations. Approximately half of all M. nattereri were associated with the same individuals when recaptured, with many associations being long-term (>100 days). In contrast, M. daubentonii were sexually segregated; only a quarter of pairs were associated at recapture after a few days, and inter-sex associations were not long-lasting. Social groups of M. nattereri and female M. daubentonii had small roost home ranges (mean 0.2 km2 in each case). Intra-specific overlap was low, but inter-specific overlap was high, suggesting territoriality within but not between species. M. daubentonii bachelor colonies did not appear to be excluded from roosting areas used by females. Conclusions: Our data suggest marked species- and sex-specific patterns of disease and information transmission are likely between bats of the same genus despite sharing a common habitat. The clear partitioning of the woodland amongst social groups, and their apparent reliance on small patches of habitat for roosting, means that localised woodland management may be more important to bat conservation than previously recognised

Population-based laboratory surveillance for Giardia sp. and Cryptosporidium sp. infections in a large Canadian health region

BACKGROUND: Giardia lamblia (intestinalis) and Cryptosporidium parvum are the two most important intestinal parasites infecting North Americans but there is a paucity of active population-based surveillance data from Canada. This study determined the incidence of and demographic risk factors for developing Giardia sp. and Cryptosporidium sp. infections in a general Canadian population. METHODS: Population-based laboratory surveillance was conducted among all residents of the Calgary Health Region (CHR; population ≅ 1 million) during May 1, 1999 and April 30, 2002. RESULTS: Giardia sp. infection occurred at a rate of 19.6 per 100,000 populations per year. Although the yearly incidence was stable, a significant seasonal variation was observed with a peak in late summer to early fall. Males were at higher risk for development of this infection as compared to females (21.2 vs. 17.9 per 100,000/yr; relative risk (RR) 1.19; 95% confidence interval (CI), 1.00–1.40, p = 0.047), and there was a significant decrease in risk associated with an increasing age. Cryptosporidium sp. infection occurred at an overall rate of 6.0 per 100,000 populations per year although a large outbreak of Cryptosporidium sp. infections occurred in the second half of the summer of 2001. During August and September of 2001, the incidence of cryptosporidiosis was 55.1 per 100,000 per year as compared to 3.1 per 100,000 per year for the remainder of the surveillance period (p < 0.0001). Cryptosporidiosis was largely a disease of children with an incidence of 17.8 per 100,000 per year occurring among those aged < 20 years of age compared to 1.25 per 100,000 per year for adults ≥ 20 years of age (RR 14.19; 95% CI, 9.77–21.11; p < 0.0001). CONCLUSION: This study provides important information on the occurrence and demographic risk groups for acquisition of giardiasis and cryptosporidiosis in a non-selected Canadian population

Time variations in the transmissibility of pandemic influenza in Prussia, Germany, from 1918–19

<p>Abstract</p> <p>Background</p> <p>Time variations in transmission potential have rarely been examined with regard to pandemic influenza. This paper reanalyzes the temporal distribution of pandemic influenza in Prussia, Germany, from 1918–19 using the daily numbers of deaths, which totaled 8911 from 29 September 1918 to 1 February 1919, and the distribution of the time delay from onset to death in order to estimate the effective reproduction number, Rt, defined as the actual average number of secondary cases per primary case at a given time.</p> <p>Results</p> <p>A discrete-time branching process was applied to back-calculated incidence data, assuming three different serial intervals (i.e. 1, 3 and 5 days). The estimated reproduction numbers exhibited a clear association between the estimates and choice of serial interval; i.e. the longer the assumed serial interval, the higher the reproduction number. Moreover, the estimated reproduction numbers did not decline monotonically with time, indicating that the patterns of secondary transmission varied with time. These tendencies are consistent with the differences in estimates of the reproduction number of pandemic influenza in recent studies; high estimates probably originate from a long serial interval and a model assumption about transmission rate that takes no account of time variation and is applied to the entire epidemic curve.</p> <p>Conclusion</p> <p>The present findings suggest that in order to offer robust assessments it is critically important to clarify in detail the natural history of a disease (e.g. including the serial interval) as well as heterogeneous patterns of transmission. In addition, given that human contact behavior probably influences transmissibility, individual countermeasures (e.g. household quarantine and mask-wearing) need to be explored to construct effective non-pharmaceutical interventions.</p

Natural Reward Experience Alters AMPA and NMDA Receptor Distribution and Function in the Nucleus Accumbens

Natural reward and drugs of abuse converge upon the mesolimbic system which mediates motivation and reward behaviors. Drugs induce neural adaptations in this system, including transcriptional, morphological, and synaptic changes, which contribute to the development and expression of drug-related memories and addiction. Previously, it has been reported that sexual experience in male rats, a natural reward behavior, induces similar neuroplasticity in the mesolimbic system and affects natural reward and drug-related behavior. The current study determined whether sexual experience causes long-lasting changes in mating, or ionotropic glutamate receptor trafficking or function in the nucleus accumbens (NAc), following 3 different reward abstinence periods: 1 day, 1 week, or 1 month after final mating session. Male Sprague Dawley rats mated during 5 consecutive days (sexual experience) or remained sexually naïve to serve as controls. Sexually experienced males displayed facilitation of initiation and performance of mating at each time point. Next, intracellular and membrane surface expression of N-methyl-D-aspartate (NMDA: NR1 subunit) and α-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA: GluA1, GluA2 subunits) receptors in the NAc was determined using a bis(sulfosuccinimidyl)suberate (BS3) protein cross-linking assay followed by Western Blot analysis. NR1 expression was increased at 1 day abstinence both at surface and intracellular, but decreased at surface at 1 week of abstinence. GluA2 was increased intracellularly at 1 week and increased at the surface after 1 month of abstinence. Finally, whole-cell patch clamp electrophysiological recordings determined reduced AMPA/NMDA ratio of synaptic currents in NAc shell neurons following stimulation of cortical afferents in sexually experienced males after all reward abstinence periods. Together, these data show that sexual experience causes long-term alterations in glutamate receptor expression and function in the NAc. Although not identical, this sex experience-induced neuroplasticity has similarities to that caused by psychostimulants, suggesting common mechanisms for reinforcement of natural and drug reward

Early efforts in modeling the incubation period of infectious diseases with an acute course of illness

The incubation period of infectious diseases, the time from infection with a microorganism to onset of disease, is directly relevant to prevention and control. Since explicit models of the incubation period enhance our understanding of the spread of disease, previous classic studies were revisited, focusing on the modeling methods employed and paying particular attention to relatively unknown historical efforts. The earliest study on the incubation period of pandemic influenza was published in 1919, providing estimates of the incubation period of Spanish flu using the daily incidence on ships departing from several ports in Australia. Although the study explicitly dealt with an unknown time of exposure, the assumed periods of exposure, which had an equal probability of infection, were too long, and thus, likely resulted in slight underestimates of the incubation period

Dual Function of the NK Cell Receptor 2B4 (CD244) in the Regulation of HCV-Specific CD8+ T Cells

The outcome of viral infections is dependent on the function of CD8+ T cells which are tightly regulated by costimulatory molecules. The NK cell receptor 2B4 (CD244) is a transmembrane protein belonging to the Ig superfamily which can also be expressed by CD8+ T cells. The aim of this study was to analyze the role of 2B4 as an additional costimulatory receptor regulating CD8+ T cell function and in particular to investigate its implication for exhaustion of hepatitis C virus (HCV)-specific CD8+ T cells during persistent infection. We demonstrate that (i) 2B4 is expressed on virus-specific CD8+ T cells during acute and chronic hepatitis C, (ii) that 2B4 cross-linking can lead to both inhibition and activation of HCV-specific CD8+ T cell function, depending on expression levels of 2B4 and the intracellular adaptor molecule SAP and (iii) that 2B4 stimulation may counteract enhanced proliferation of HCV-specific CD8+ T cells induced by PD1 blockade. We suggest that 2B4 is another important molecule within the network of costimulatory/inhibitory receptors regulating CD8+ T cell function in acute and chronic hepatitis C and that 2B4 expression levels could also be a marker of CD8+ T cell dysfunction. Understanding in more detail how 2B4 exerts its differential effects could have implications for the development of novel immunotherapies of HCV infection aiming to achieve immune control

Cerebrovascular mental stress reactivity is impaired in hypertension

<p>Abstract</p> <p>Background</p> <p>Brachial artery reactivity in response to shear stress is altered in subjects with hypertension. Since endothelial dysfunction is generalized, we hypothesized that carotid artery (CA) reactivity would also be altered in hypertension.</p> <p>Purpose</p> <p>To compare (CA endothelium-dependent vasodilation in response to mental stress in normal and hypertensive subjects.</p> <p>Methods</p> <p>We evaluated CA reactivity to mental stress in 10 young healthy human volunteers (aged 23 ± 4 years), 20 older healthy volunteers (aged 49 ± 11 years) and in 28 patients with essential hypertension (aged 51 ± 13 years). In 10 healthy volunteers and 12 hypertensive subjects, middle cerebral artery (MCA) PW transcranial Doppler was performed before and 3 minutes after mental stress.</p> <p>Results</p> <p>Mental stress by Stroop color word conflict, math or anger recall tests caused CA vasodilation in young healthy subjects (0.61 ± 0.06 to 0.65 ± 0.07 cm, p < 0.05) and in older healthy subjects (0.63 ± 0.06 to 0.66 ± 0.07 cm, p < 0.05), whereas no CA vasodilation occurred in hypertensive subjects (0.69 ± 0.06 to 0.68 ± 0.07 cm; p, NS). CA blood flow in response to mental stress increased in young healthy subjects (419 ± 134 to 541 ± 209 ml, p < 0.01 vs. baseline) and in older healthy subjects (351 ± 114 to 454 ± 136 ml, p < 0.01 vs. baseline) whereas no change in blood flow (444 ± 143 vs. 458 ± 195 ml; p, 0.59) occurred in hypertensive subjects. There was no difference in the CA response to nitroglycerin in healthy and hypertensive subjects. Mental stress caused a significant increase in baseline to peak MCA systolic (84 ± 22 to 95 ± 22 cm/s, p < 0.05), diastolic (42 ± 12 to 49 ± 14 cm/s, p < 0.05) as well as mean (30 ± 13 to 39 ± 13 cm/s, p < 0.05) PW Doppler velocities in normal subjects, whereas no change in systolic (70 ± 18 to 73 ± 22 cm/s, p < 0.05), diastolic (34 ± 14 to 37 ± 14 cm/s, p = ns) or mean velocities (25 ± 9 to 26 ± 9 cm/s, p = ns) occurred in hypertensive subjects, despite a similar increase in heart rate and blood pressure in response to mental stress in both groups.</p> <p>Conclusion</p> <p>Mental stress produces CA vasodilation and is accompanied by an increase in CA and MCA blood flow in healthy subjects. This mental stress induced CA vasodilation and flow reserve is attenuated in subjects with hypertension and may reflect cerebral vascular endothelial dysfunction. Assessment of mental stress induced CA reactivity by ultrasound is a novel method for assessing the impact of hypertension on cerebrovascular endothelial function and blood flow reserve.</p

Recurrent Chromosome 16p13.1 Duplications Are a Risk Factor for Aortic Dissections

Chromosomal deletions or reciprocal duplications of the 16p13.1 region have been implicated in a variety of neuropsychiatric disorders such as autism, schizophrenia, epilepsies, and attention-deficit hyperactivity disorder (ADHD). In this study, we investigated the association of recurrent genomic copy number variants (CNVs) with thoracic aortic aneurysms and dissections (TAAD). By using SNP arrays to screen and comparative genomic hybridization microarrays to validate, we identified 16p13.1 duplications in 8 out of 765 patients of European descent with adult-onset TAAD compared with 4 of 4,569 controls matched for ethnicity (P = 5.0×10−5, OR = 12.2). The findings were replicated in an independent cohort of 467 patients of European descent with TAAD (P = 0.005, OR = 14.7). Patients with 16p13.1 duplications were more likely to harbor a second rare CNV (P = 0.012) and to present with aortic dissections (P = 0.010) than patients without duplications. Duplications of 16p13.1 were identified in 2 of 130 patients with familial TAAD, but the duplications did not segregate with TAAD in the families. MYH11, a gene known to predispose to TAAD, lies in the duplicated region of 16p13.1, and increased MYH11 expression was found in aortic tissues from TAAD patients with 16p13.1 duplications compared with control aortas. These data suggest chromosome 16p13.1 duplications confer a risk for TAAD in addition to the established risk for neuropsychiatric disorders. It also indicates that recurrent CNVs may predispose to disorders involving more than one organ system, an observation critical to the understanding of the role of recurrent CNVs in human disease and a finding that may be common to other recurrent CNVs involving multiple genes