Assessing climate change impacts on the near-term stability of the wind energy resource over the United States.

The energy sector comprises approximately two-thirds of global total greenhouse gas emissions. For this and other reasons, renewable energy resources including wind power are being increasingly harnessed to provide electricity generation potential with negligible emissions of carbon dioxide. The wind energy resource is naturally a function of the climate system because the "fuel" is the incident wind speed and thus is determined by the atmospheric circulation. Some recent articles have reported historical declines in measured near-surface wind speeds, leading some to question the continued viability of the wind energy industry. Here we briefly articulate the challenges inherent in accurately quantifying and attributing historical tendencies and making robust projections of likely future wind resources. We then analyze simulations from the current generation of regional climate models and show, at least for the next 50 years, the wind resource in the regions of greatest wind energy penetration will not move beyond the historical envelope of variability. Thus this work suggests that the wind energy industry can, and will, continue to make a contribution to electricity provision in these regions for at least the next several decades.

20% of US electricity from wind will have limited impacts on system efficiency and regional climate.

Impacts from current and future wind turbine (WT) deployments necessary to achieve 20% electricity from wind are analyzed using high resolution numerical simulations over the eastern USA. Theoretical scenarios for future deployments are based on repowering (i.e. replacing with higher capacity WTs) thus avoiding competition for land. Simulations for the contemporary climate and current WT deployments exhibit good agreement with observed electricity generation efficiency (gross capacity factors (CF) from simulations = 45-48%, while net CF for WT installed in 2016 = 42.5%). Under the scenario of quadrupled installed capacity there is a small decrease in system-wide efficiency as indicated by annual mean CF. This difference is approximately equal to that from the two simulation years and may reflect saturation of the wind resource in some areas. WT modify the local near-surface climate in the grid cells where they are deployed. The simulated impact on near-surface climate properties at both the regional and local scales does not increase with increasing WT installed capacity. Climate impacts from WT are modest compared to regional changes induced by historical changes in land cover and to the global temperature perturbation induced by use of coal to generate an equivalent amount of electricity.

Particle fluxes above forests: observations, methodological considerations and method comparisons.

This paper reports a study designed to test, evaluate and compare micro-meteorological methods for determining the particle number flux above forest canopies. Half-hour average particle number fluxes above a representative broad-leaved forest in Denmark derived using eddy covariance range from -7x10(7) m(-2) s(-1) (1st percentile) to 5x10(7) m(-2) s(-1) (99th percentile), and have a median value of -1.6x10(6) m(-2) s(-1). The statistical uncertainties associated with the particle number flux estimates are larger than those for momentum fluxes and imply that in this data set approximately half of the particle number fluxes are not statistically different to zero. Particle number fluxes from relaxed eddy accumulation (REA) and eddy covariance are highly correlated and of almost identical magnitude. Flux estimates from the co-spectral and dissipation methods are also correlated with those from eddy covariance but exhibit higher absolute magnitude of fluxes.

Modeling the impact of sea-spray on particle concentrations in a coastal city.

With the worlds population becoming increasingly focused on coastal locations there is a need to better understand the interactions between anthropogenic emissions and marine atmospheres. Herein an atmospheric chemistry-transport model is used to assess the impacts of sea-spray chemistry on the particle composition in and downwind of a coastal city--Vancouver, British Columbia. It is shown that the model can reasonably represent the average features of the gas phase and particle climate relative to in situ measurements. It is further demonstrated that reactions in/on sea-spray affect the entire particle ensemble and particularly the size distribution of particle nitrate, but that the importance of these heterogeneous reactions is critically dependent on both the initial vertical profile of sea spray and the sea-spray source functions. The results emphasize the need for improved understanding of sea spray production and dispersion and further that model analyses of air quality in coastal cities conducted without inclusion of sea-spray interactions may yield mis-leading results in terms of emission sensitivities of particle composition and concentrations.

MEAD: an interdisciplinary study of the marine effects of atmospheric deposition in the Kattegat.

This paper summarises the results of the EU funded MEAD project, an interdisciplinary study of the effects of atmospheric nitrogen deposition on the Kattegat Sea between Denmark and Sweden. The study considers emissions of reactive nitrogen gases, their transport, transformations, deposition and effects on algal growth together with management options to reduce these effects. We conclude that atmospheric deposition is an important source of fixed nitrogen to the region particularly in summer, when nitrogen is the limiting nutrient for phytoplankton growth, and contributes to the overall eutrophication pressures in this region. However, we also conclude that it is unlikely that atmospheric deposition can, on its own, induce algal blooms in this region. A reduction of atmospheric nitrogen loads to this region will require strategies to reduce emissions of ammonia from local agriculture and Europe wide reductions in nitrous oxide emissions.

Using satellite-based measurements to explore spatiotemporal scales and variability of drivers of new particle formation.

New particle formation (NPF) can potentially alter regional climate by increasing aerosol particle (hereafter particle) number concentrations and ultimately cloud condensation nuclei. The large scales on which NPF is manifest indicate potential to use satellite-based (inherently spatially averaged) measurements of atmospheric conditions to diagnose the occurrence of NPF and NPF characteristics. We demonstrate the potential for using satellite-based measurements of insolation (UV), trace gas concentrations (sulfur dioxide (SO2), nitrogen dioxide (NO2), ammonia (NH3), formaldehyde (HCHO), and ozone (O3)), aerosol optical properties (aerosol optical depth (AOD) and Ångström exponent (AE)), and a proxy of biogenic volatile organic compound emissions (leaf area index (LAI) and temperature (T)) as predictors for NPF characteristics: formation rates, growth rates, survival probabilities, and ultrafine particle (UFP) concentrations at five locations across North America. NPF at all sites is most frequent in spring, exhibits a one-day autocorrelation, and is associated with low condensational sink (AOD × AE) and HCHO concentrations, and high UV. However, there are important site-to-site variations in NPF frequency and characteristics, and in which of the predictor variables (particularly gas concentrations) significantly contribute to the explanatory power of regression models built to predict those characteristics. This finding may provide a partial explanation for the reported spatial variability in skill of simple generalized nucleation schemes in reproducing observed NPF. In contrast to more simple proxies developed in prior studies (e.g., based on AOD, AE, SO2, and UV), use of additional predictors (NO2, NH3, HCHO, LAI, T, and O3) increases the explained temporal variance of UFP concentrations at all sites.

Opioid involvement in behavior modifications of mice infected with the parasitic nematode, Nippostrongylus brasiliensis.

Several studies have documented the opiate effects of parasitic infection on experimental animals. The current study examined the relationships between infection with the intestinal nematode, Nippostrongylus brasiliensis with analgesia and activity levels. Male white mice infected with N. brasiliensis displayed a significant increase in thermal latency thresholds that rose through the duration of infection and subsided with its termination. Analgesia first became apparent on day three-post infection but did not reach statistical significance (p < 0.05) until day 7 post infection. The maximum analgesia was reached on day 8-post infection and gradually declined. By day 15 post infection, there was no significant difference in the latency times between control and infected mice. The initial significant difference in latency roughly corresponded with the onset of egg production by the parasite. The peak difference in latency times and their subsequent decline also parallels peak egg production and the decline in egg production as the infection subsided. Both naloxone and naltrindole significantly reduced the latency times (p < 0.05) of infected mice. There was also a significant difference in total ambulatory activity levels between infected and control mice. Activity levels began to decline on the second day post infection but did not reach a statistically significant difference (p < 0.05) from the controls until 9th day post infection. Infected mice that were injected with either naloxone or naltrindole had a significantly higher activity level than the infected mice injected with saline.

Temporal variation in morphological and genetic characteristics within a hybrid population of Culex pipiens (Diptera: Culicidae).

Samples of mosquitoes in the Culex pipiens L. complex from Memphis, Tenn., were collected from June to November 1985 and examined in regard to allozyme frequencies and ratios of the two arms of the phallosome of the male genitalia (DV/D). The dominant allozymes of hexokinase (HkA) and 6-phosphogluconate dehydrogenase (PgdF) significantly increased in frequency during this period as did the mean DV/D ratio. An analysis of gene frequencies by species group designated by DV/D ratios revealed no significant differences among Cx. pipiens, Cx. quinquefasciatus Say, and intermediates. The lack of association of gene frequencies with the taxa determined by the DV/D ratio indicated that although allozyme frequencies were correlated temporally with the DV/D ratio in the population, they were not associated with subspecies. These results are consistent with previous work that has shown latitudinal association and thermal stability differences in the major allozymes of these enzymes in the Cx. pipiens complex.

REVEAL II: seasonality and spatial variability of particle and visibility conditions in the Fraser Valley.

This paper presents data collected during a year-long field experiment (REVEAL II) in the Fraser Valley, British Columbia. The data are used to provide information regarding ambient visibility conditions and fine particle concentrations in the valley. Although average fine mass measured during REVEAL II was 8-9 microg m(-3), the fine particle mass has high light-scattering efficiencies and the visual range is frequently below publicly defined acceptable levels. For example, data indicate that during the fall the visual range is frequently below 20 km even under favorable meteorological conditions. Source apportionment analyses of mass and particle light-scattering indicate motor vehicles may contribute as much as 40% of the fine particle mass in the central valley and up to one-third of the particle light-scattering. In addition to characterizing conditions in the Fraser Valley, slides taken at a number of sites during REVEAL II are used to evaluate a simple method for obtaining (classed) quantitative estimates of visual range from this medium without requiring access to specialized instrumentation.

PM10 in Canada.

Annual mean PM10 concentrations in Canadian cities are between five and eight times estimated background levels. Federal and Provincial agencies in Canada are currently reviewing particulate standards, and considering replacing current total suspended particulate (TSP) standards with standards to regulate PM10 (thoracic particles) because epidemiological research suggests that this size fraction is active in the production of adverse health impacts. This paper documents the spatial and temporal variability of current particulate levels in Canada, and compares them with TSP standards presently implemented in Canada and PM10 standards as applied by the US EPA, state of California and the World Health Organization (WHO). Twenty-four-hour averaged PM10 data from the 52 sites described here exceed the standard as applied in California on up to 35% of monitoring days. The threshold suggested by the WHO for 24-h averaged concentrations is passed at the majority of the sites on approximately 5% of monitoring days.

Secondary organic aerosols: formation potential and ambient data.

Organic aerosols comprise a significant fraction of the total atmospheric particle loading and are associated with radiative forcing and health impacts. Ambient organic aerosol concentrations contain both a primary and secondary component. Herein, fractional aerosol coefficients (FAC) are used in conjunction with measurements of volatile organic compounds (VOC) to predict the formation potential of secondary organic aerosols (SOA) in the Lower Fraser Valley (LFV) of British Columbia. The predicted concentrations of SOA show reasonable accord with ambient aerosol measurements and indicate considerable seasonal variability in SOA potential. Particulate carbon contributes only approx. 3% of total carbon concentrations in the LFV, and it is shown that variability in total carbon concentrations is significantly larger than variability in gas/particle partitioning.

Nitrogen deposition to and cycling in a deciduous forest.

The project described here seeks to answer questions regarding the role increased nitrogen (N) deposition is playing in enhanced carbon (C) sequestration in temperate mid-latitude forests, using detailed measurements from an AmeriFlux tower in southern Indiana (Morgan-Monroe State Forest, or MMSF). The measurements indicate an average atmosphere-surface N flux of approximately 6 mg-N m(-2) day(-1) during the 2000 growing season, with approximately 40% coming from dry deposition of ammonia (NH3), nitric acid (HNO3), and particle-bound N. Wet deposition and throughfall measurements indicate significant canopy uptake of N (particularly NH4+) at the site, leading to a net canopy exchange (NCE) of -6 kg-N ha(-1) for the growing season. These data are used in combination with data on the aboveground C:N ratio, litterfall flux, and soil net N mineralization rates to indicate the level of potential perturbation of C sequestration at this site.

Evidence of opiates and opioid neuropeptides and their immune effects in parasitic invertebrates representing three different phyla: Schistosoma mansoni, Theromyzon tessulatum, Trichinella spiralis.

Studies done in our laboratories have demonstrated that the parasitic trematode, Schistosoma mansoni is capable of producing several proopiomelanocortin (POMC) peptides including beta-endorphin, adrenocorticotropin (ACTH), melanocyte stimulating hormone (alphaMSH) and enkephalin as well as morphine. Some of these opioids have been demonstrated to be immunosuppressive and may play an important part in immune evasion by these parasites. The parasitic nematode Trichinella spiralis also produces immune suppressive substances in vitro as well as causes immune suppression in its encysted stage in vivo. We recently have demonstrated the presence of morphine in both infected mice and in the nematode by HPLC and RIA. In a recent study of the leech Theromyzon tessulatum, we demonstrated the presence of proopiomelanocortin (POMC) and its derived peptides, ACTH and alphaMSH, in the immune tissues. The peptide was cloned and extensively purified by HPGPC and reversed-phase HPLC, and then sequenced. The 25.4 kDa protein was purified by gel permeation chromatography, anti-ACTH-affinity column separation followed by reversed-phase HPLC. Its amino acid determination was performed by Edman degradation, enzymatic treatments and electrospray mass spectrometry. The structure of the leech POMC-like precursor and its derived peptides demonstrates considerable amino acid sequence similarity with mammalian POMC. Taken together, these studies demonstrate that opiates and opioid neuropetides are present in invertebrates and their immunoregulatory actions have been conserved during evolution. The role of opiates and opioid peptides in immune and behavior modification of hosts is also discussed.

The effects of opiates and opioid neuropeptides on mosquito hemocytes.

The effects of morphine, Met-enkephalin, and its synthetic analogue DAMA on the hemocytes of Culex pipiens mosquitoes were examined in vitro. Morphine caused the cells to round up and decrease in area. Met-enkephalin caused the cells to become ameboid and increase in area. This effect was accentuated with the addition of the neutral endopeptidase blocker phosphoramidon. DAMA caused a similar but greater enhancement of immune activation which was blocked by the opiate antagonist, naloxone. These results were similar to those seen in other invertebrate hemocytes.

Opiate alkaloids in Ascaris suum.

The parasitic worm Ascaris suum contains the opiate alkaloids morphine and morphine-6-glucuronide as determined by HPLC coupled to electrochemical detection and by gas chromatography/mass spectrometry. The level of morphine in muscle tissue of female and male is 252 +/- 32.68, 1168 +/- 278 and 180 +/- 23.47 (ng/g of wet tissue), respectively. The level of M6G in muscle tissue of female and male is 167 +/- 28.37 and 92 +/- 11.45 (ng/g of wet tissue), respectively. Furthermore, Ascaris maintained for 5 days contained a significant amount of morphine, as did their medium, demonstrating their ability to synthesize the opiate alkaloid. The anatomic distribution of morphine was examined by indirect immunofluorescent staining and HPLC of various tissues dissected from male and female adult worms. Immunofluorescence revealed morphine in the subcuticle layers, in the animals' nerve chords and in the female reproductive organs. Morphine was found to be most prevalent in the muscle tissue and there is significantly more morphine in females than males, probably due to the large amounts in the female uterus. Morphine (10(-9) M) and morphine-6-glucuronide (10(-9) M) stimulated the release of NO from Ascaris muscle tissue. Naloxone (10(-7) M), and L-NAME (10(-6) M) blocked (P < 0.005) morphine-stimulated NO release from A. suum muscle. CTOP (10(-7) M) did not block morphine's NO release. However, naloxone could not block M6G stimulated NO release by muscle tissue, whereas CTOP (10(-7) M) blocked its release. These findings were in seeming contradiction to our inability to isolate a mu opiate receptor messenger RNA by RT-PCR using a human mu primer. This suggests that a novel mu opiate receptor was present and selective toward M6G.

The effect of opioids and their antagonists on the nocifensive response of Caenorhabditis elegans to noxious thermal stimuli.

Opiates modulate nociception in vertebrates. This has also been demonstrated in a number of invertebrate models. Herein, the effect of the opiate morphine and opioid neuropeptides Endomorphin 1 and 2 on the thermal avoidance (Tav) behavior of Caenorhabditis elegans is explored. Adult wild-type C. elegans N2 were collected from NGM plates using M9 buffer and exposed to morphine and endomorphine 1 and 2 in concentrations between 10(-8) and 10(-4) M (2.5 pmol/mg to 25 nmol/mg) for 30 min and tested for Tav. The opioid receptor antagonists Naloxone and CTOP were tested in combination with the drugs. Forty-seven percentage of the morphine exposed worms exhibited a class I response versus 76% of the control group (P < 0.001). Endomorphin 1 and 2 also caused a statistically significant reduction in class I responses, 36 and 39%, respectively. These effects were reversed with Naloxone and CTOP. Thermonocifensive behavior in C. elegans is modulated by opioids.

Dopamine- and octopamine-sensitive adenylate cyclase in the brain of adult Culex pipiens mosquitoes.

The effects of dopamine and octopamine on adenylate cyclase activity were studied on the head homogenate of adult Culex pipiens mosquitoes in vitro. Both dopamine and octopamine were shown to increase the cyclic AMP content in the homogenate. The antagonist haloperidol blocked the production of cyclic AMP induced from dopamine but had no effect on the production of cyclic AMP induced by octopamine at the concentrations tested. The opiate agonist etorphine was ineffective at reducing cyclic AMP levels induced by either dopamine or octopamine at the concentrations tested.

Leech immunocytes contain proopiomelanocortin: nitric oxide mediates hemolymph proopiomelanocortin processing.

This report establishes the presence of mammalian-like proopiomelanocotropic hormone (POMC), and six of its peptides, including adrenocorticotropic hormone (ACTH) and melanocyte-stimulating hormone (MSH), in the immune tissues of the leech Theromyzon tessulatum. The 25.4-kDa protein was purified by high pressure gel permeation chromatography, anti-ACTH-affinity column, and reverse-phase HPLC. Its characterization was performed by Edman degradation, enzymatic treatments, and electrospray mass spectrometry. Leech POMC exhibits considerable amino acid sequence similarity to mammalian POMC. Of the six peptides, three showed high sequence similarity to their vertebrate counterparts met-enkephalin, alpha-MSH, and ACTH: 100, 84.6, and 70%, respectively; whereas gamma-MSH, beta-endorphin, and gamma-lipotropin hormone exhibited only 45, 20, and 10% sequence identity, respectively. No dibasic amino acid residues were found at the C terminus of the gamma- and beta-MSH peptides. In contrast, the leech alpha-MSH was flanked at its C-terminal by the Gly-Arg-Lys amidation signal. ACTH and corticotropin-like intermediary pituitary peptide were also C-terminally flanked by dibasic amino acid residues. The coding region of leech POMC was obtained by reverse transcription-PCR using degenerated oligonucleotide primers. Circulating levels of ACTH and MSH were 10 and 1 fmol/microl hemolymph, respectively. Morphine, in a dose-dependent manner, increased the levels of both peptides threefold; this effect was blocked by naloxone treatment. Similar results were found with the anandamide. Leech ACTH was processed to MSH by the enzymes neutral endopeptidase (24.11) and angiotensin-converting enzyme. Leech alpha-MSH had the same activity as authentic alpha-MSH in two bioasssay systems. Taken together, the study demonstrates that POMC is present in invertebrates and its immunoregulatory actions have been conserved during evolution.

Dracunculus medinensis and Schistosoma mansoni contain opiate alkaloids.

The results of analysis, by high-performance liquid chromatography coupled with electrochemical detection and by nano-electrospray-ionization, double quadrupole/orthogonal-acceleration, time-of-flight mass spectrometry, indicate that adult Dracunculus medinensis and Schistosoma mansoni both contain the opiate alkaloid morphine and that D. medinesis also contains the active metabolite of morphine, morphine 6-glucuronide. From these and previous observations, it would appear that many helminths are probably using opiate alkaloids as potent immunosuppressive and antinociceptive signal molecules, to down-regulate immunosurveillance responsiveness and pain signalling in their hosts.