North American Pollution Outflow and the Trapping of Convectively Lifted Pollution by Upper-Level Anticyclone

We examine the major outflow pathways for North American pollution to the Atlantic in summer by conducting a 4-year simulation with the GEOS-CHEM global chemical transport model, including a coupled ozone-aerosol simulation with 1° × 1° horizontal resolution for summer 2000. The outflow is driven principally by cyclones tracking eastward across North America at 45–55°N, every 5 days on average. Anthropogenic and fire effluents from western North America are mostly transported north and east, eventually merging with the eastern U.S. pollution outflow to the Atlantic. A semipermanent upper-level anticyclone traps the convective outflow and allows it to age in the upper troposphere over the United States for several days. Rapid ozone production takes place in this outflow, driven in part by anthropogenic and lightning NO x and in part by HO x radicals produced from convectively lifted CH2O that originates from biogenic isoprene. This mechanism could explain ozonesonde observations of elevated ozone in the upper troposphere over the southeastern United States. Asian and European pollution influences in the North American outflow to the Atlantic are found to be dispersed into the background and do not generate distinct plumes. Satellite observations of CO columns from MOPITT and of aerosol optical depths (AODs) from MODIS provide useful mapping of outflow events, despite their restriction to clear-sky scenes.Earth and Planetary Science

Loss of Sialic Acid Binding Domain Redirects Protein σ1 to Enhance M Cell-Directed Vaccination

Ovalbumin (OVA) genetically fused to protein sigma 1 (pσ1) results in tolerance to both OVA and pσ1. Pσ1 binds in a multi-step fashion, involving both protein- and carbohydrate-based receptors. To assess the relative pσ1 components responsible for inducing tolerance and the importance of its sialic binding domain (SABD) for immunization, modified OVA-pσ1, termed OVA-pσ1(short), was deleted of its SABD, but with its M cell targeting moiety intact, and was found to be immunostimulatory and enhanced CD4+ and CD8+ T cell proliferation. When used to nasally immunize mice given with and without cholera toxin (CT) adjuvant, elevated SIgA and serum IgG responses were induced, and OVA-pσ1(s) was more efficient for immunization than native OVA+CT. The immune antibodies (Abs) were derived from elevated Ab-forming cells in the upper respiratory tissues and submaxillary glands and were supported by mixed Th cell responses. Thus, these studies show that pσ1(s) can be fused to vaccines to effectively elicit improved SIgA responses

Inventory of Boreal Fire Emissions for North America in 2004: The Importance of Peat Burning and Pyro-Convective Injection

The summer of 2004 was one of the largest fire seasons on record for Alaska and western Canada. We construct a daily bottom-up fire emission inventory for that season, including consideration of peat burning and high-altitude (buoyant) injection, and evaluate it in a global chemical transport model (the GEOS-Chem CTM) simulation of CO through comparison with MOPITT satellite and ICARTT aircraft observations. The inventory is constructed by combining daily area burned reports and MODIS fire hot spots with estimates of fuel consumption and emission factors based on ecosystem type. We estimate the contribution from peat burning using drainage and peat distribution maps for Alaska and Canada; 17% of the reported 5.1 × 106 ha burned were located in peatlands in 2004. Our total estimate of North American fire emissions during the summer of 2004 is 30 Tg CO, including 11 Tg from peat. Including peat burning in the GEOS-Chem simulation improves agreement with MOPITT observations. The long-range transport of fire plumes observed by MOPITT suggests that the largest fires injected a significant fraction of their emissions in the upper troposphere.Earth and Planetary SciencesEngineering and Applied Science

Concentrations and Sources of Organic Carbon Aerosol in the Free Troposphere over North America

Aircraft measurements of water-soluble organic carbon (WSOC) aerosol over NE North America during summer 2004 (ITCT-2K4) are simulated with a global chemical transport model (GEOS-Chem) to test our understanding of the sources of organic carbon (OC) aerosol in the free troposphere (FT). Elevated concentrations were observed in plumes from boreal fires in Alaska and Canada. WSOC aerosol concentrations outside of these plumes average 0.9 ± 0.9 μg C m−3 in the FT (2–6 km). The corresponding model value is 0.7 ± 0.6 μg C m−3, including 42% from biomass burning, 36% from biogenic secondary organic aerosol (SOA), and 22% from anthropogenic emissions. Previous OC aerosol observations over the NW Pacific in spring 2001 (ACE-Asia) averaged 3.3 ± 2.8 μg C m−3 in the FT, compared to a model value of 0.3 ± 0.3 μg C m−3. WSOC aerosol concentrations in the boundary layer (BL) during ITCT-2K4 are consistent with OC aerosol observed at the IMPROVE surface network. The model is low in the boundary layer by 30%, which we attribute to secondary formation at a rate comparable to primary anthropogenic emission. Observed WSOC aerosol concentrations decrease by a factor of 2 from the BL to the FT, as compared to a factor of 10 decrease for sulfate, indicating that most of the WSOC aerosol in the FT originates in situ. Despite reproducing mean observed WSOC concentrations in the FT to within 25%, the model cannot account for the variance in the observations (R = 0.21). Covariance analysis of FT WSOC aerosol with other measured chemical variables suggests an aqueous-phase mechanism for SOA generation involving biogenic precursors.Earth and Planetary SciencesEngineering and Applied Science

Регулирование свойств дисперсий для их электрокинетической обработки

Для ефективної обробки дисперсних систем, яка базується на використанні зовнішніх електричних полів, необхідно забезпечити максимально можливі для конкретної системи швидкості електрофорезу та електроосмосу. У випадку, коли дисперсія включає в себе глинисту складову, основним фактором, який дає можливість регулювати її електрокінетичні характеристики, є рН рівноважного розчину. У зв’язку з цим у роботі досліджено кінетику зміни рН порового розчину при введенні кислих та лужних розчинів (NaOH і HCl). Встановлено, що при заданій вологості дисперсії в широкому інтервалі концентрацій використаних електролітів рівноважні значення рН порового розчину досягаються через 24 год. Проведені дослідження швидкості електрофорезу та розраховані на його основі значення електрокінетичного потенціалу показали, що максимальні величини потенціалу досягаються при 8 < pH < 12. Цьому ж інтервалу рН відповідають і максимальні стаціонарні швидкості електроосмосу, хоча через форму пор дисперсії та зовнішній гідродинамічний опір експериментальної комірки їх значення на 20—30 % нижчі від розрахованих.For efficient processing of disperse systems based on the use of external electric fields the highest possible velocities of electrophoresis and electroosmosis for a particular system should be ensured. In case of dispersion, which includes a clay component, the main factor that allows adjusting of its electrokinetic properties is pH of equilibrium solution. In this regard, in present work the kinetics of changes in pH of the pore solution with the introduction of acidic and alkaline solutions (NaOH and HCl) is studied. It is found that at given moisture over a wide concentration range of used electrolyte concentrations the equilibrium pH of the pore solution is achieved after 24 hours. The carried out investigations of electrophoresis velocities and the electrokinetic potentials calculated on their basis showed that the maximum value of the potential is achieved at 8 < pH < 12. The maximum values of stationary electroosmosis velocities correspond to the same range of pH values, however, due to the shape of the dispersion pores and external hydrodynamic resistance of the experimental cell their values are 20—30 % lower than estimated ones.Для эффективной обработки дисперсных систем, базирующейся на использовании внешних электрических полей, необходимо обеспечить максимально возможные для конкретной системы скорости электрофореза и электроосмоса. В случае, когда дисперсия включает в себя глинистую составляющую, основным фактором, который позволяет регулировать ее электрокинетические характеристики, является рН равновесного раствора. В связи с этим в работе исследована кинетика изменения рН порового раствора при введении кислых и щелочных растворов (NaOH и HCl). Установлено, что при заданной влажности дисперсии в широком интервале концентраций использованных электролитов равновесные значения рН порового раствора достигаются через 24 ч. Проведенные исследования скорости электрофореза и рассчитанные на его основе значения электрокинетического потенциала показали, что максимальные величины потенциала достигаются при 8 < pH < 12. Этому же интервалу рН отвечают и максимальные стационарные скорости электроосмоса, хотя из-за формы пор дисперсии и внешнего гидродинамического сопротивления экспериментальной ячейки их значения на 20—30 % ниже рассчитанных

IFNAR2 Is Required for Anti-influenza Immunity and Alters Susceptibility to Post-influenza Bacterial Superinfections

Influenza virus infections particularly when followed by bacterial superinfections (BSI) result in significant morbidities and mortalities especially during influenza pandemics. Type I interferons (IFNs) regulate both anti-influenza immunity and host susceptibility to subsequent BSIs. These type I IFNs consisting of, among others, 14 IFN-α's and a single IFN-β, are recognized by and signal through the heterodimeric type I IFN receptor (IFNAR) comprised of IFNAR1 and IFNAR2. However, the individual receptor subunits can bind IFN-β or IFN-α's independently of each other and induce distinct signaling. The role of type I IFN signaling in regulating host susceptibility to both viral infections and BSI has been only examined with respect to IFNAR1 deficiency. Here, we demonstrate that despite some redundancies, IFNAR1 and IFNAR2 have distinct roles in regulating both anti-influenza A virus (IAV) immunity and in shaping host susceptibility to subsequent BSI caused by S. aureus. We found IFNAR2 to be critical for anti-viral immunity. In contrast to Ifnar1−/− mice, IAV-infected Ifnar2−/− mice displayed both increased and accelerated morbidity and mortality compared to WT mice. Furthermore, unlike IFNAR1, IFNAR2 was sufficient to generate protection from lethal IAV infection when stimulated with IFN-β. With regards to BSI, unlike what we found previously in Ifnar1−/− mice, Ifnar2−/− mice were not susceptible to BSI induced on day 3 post-IAV, even though absence of IFNAR2 resulted in increased viral burden and an increased inflammatory environment. The Ifnar2−/− mice similar to what we previously found in Ifnar1−/− mice were less susceptible than WT mice to BSI induced on day 7 post-IAV, indicating that signaling through a complete receptor increases BSI susceptibility late during clinical IAV infection. Thus, our results support a role for IFNAR2 in induction of anti-IAV immune responses that are involved in altering host susceptibility to BSI and are essential for decreasing the morbidity and mortality associated with IAV infection. These results begin to elucidate some of the mechanisms involved in how the individual IFNAR subunits shape the anti-viral immune response. Moreover, our results highlight the importance of examining the contributions of entire receptors, as individual subunits can induce distinct outcomes as shown here

Microfold (M) cells: important immunosurveillance posts in the intestinal epithelium

The transcytosis of antigens across the gut epithelium by microfold cells (M cells) is important for the induction of efficient immune responses to some mucosal antigens in Peyer’s patches. Recently, substantial progress has been made in our understanding of the factors that influence the development and function of M cells. This review highlights these important advances, with particular emphasis on: the host genes which control the functional maturation of M cells; how this knowledge has led to the rapid advance in our understanding of M-cell biology in the steady-state and during aging; molecules expressed on M cells which appear to be used as “immunosurveillance” receptors to sample pathogenic microorganisms in the gut; how certain pathogens appear to exploit M cells to infect the host; and finally how this knowledge has been used to specifically target antigens to M cells to attempt to improve the efficacy of mucosal vaccines

The Use of Dynamic 3D Printed Cervical Spine Models in a Musculoskeletal Physical Therapy Course

Purpose: While mass-produced anatomical models are commercially available, many models are inflexible and static, and may not meet the needs of health professions students. Advances in three-dimensional (3D) printing have demonstrated tremendous potential for enhancing student learning. This study uses 3D printed cervical spine models to explore whether use of dynamic, flexible models improve student learning in a cohort of physical therapy students. Methods: 3D printed models of the cervical spine and occiput were printed using a fused deposition modeling 3D printer and polylactic acid filament, and augmented with hook and loop fasteners, foam sheets, and cords to simulate structures such as ligaments, intervertebral discs, and the spinal cord. Twenty-one second-year students enrolled in a Doctor of Physical Therapy musculoskeletal course were divided into two groups: one group had access to the augmented 3D printed models (n=11) and the other had access to commercially available models (n=10). A 10-question multiple-choice assessment was given on the cervical spine and its arthrokinematics before and after lectures and manipulation of cervical spine models. Four Likert-scale questions measuring confidence in explaining or performing a particular cervical spine movement and palpating bony landmarks were also queried. Results: There were no significant differences in the post-test scores for the dynamic and static model groups (t=.66, df=19, p=0.52), or in the confidence in explaining cervical spine movements when comparing the type of model used. Conclusions: This study did not replicate others’ findings of the effectiveness of dynamic 3D printed models. Factors may include that the length of time students manipulated models was unknown, that other studies compared 3D printed models and non-3D printed models (cadaveric donors, plastinated models, 2D images), and that 3D printing is not as effective for all anatomical regions. Despite the lack of significant differences, use of dynamic 3D printed models did not hinder learning and may complement other resources available in physical therapy educational settings