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The conceptual origins of ribosome specialization can be traced back to the earliest days of molecular biology. Yet, this field has only recently begun to gather momentum, with numerous studies identifying distinct heterogeneous ribosome populations across multiple species and model systems. It is proposed that some of these compositionally distinct ribosomes may be functionally specialized and able to regulate the translation of specific mRNAs. Identification and functional characterization of specialized ribosomes has the potential to elucidate a novel layer of gene expression control, at the level of translation, where the ribosome itself is a key regulatory player. In this review, we discuss different sources of ribosome heterogeneity, evidence for ribosome specialization, and also the future directions of this exciting field. Over the past decade, it has become increasingly apparent that ribosomes are significantly more heterogeneous than originally thought, with variation emanating from both the rRNA and protein content of ribosomes. This heterogeneity can potentially confer functional ribosome specialization, contributing to translational control, thereby identifying the ribosome as a key regulatory player in translation. Studies have uncovered interindividual and intertissue variant rRNA alleles and there has also been a recent focus on identifying functional roles for the previously enigmatic eukaryotic rRNA expansion segments. Technological advances have permitted accurate, quantitative analysis of rRNA modifications across several organisms, with functionality ascribed to certain rRNA modifications. Other work has centered on identifying specialization arising due to changes in ribosome protein composition. [ABSTRACT FROM AUTHOR]

Atmospheric mercury (Hg) deposition to forests is important because half of the land cover in the eastern USA is forest. Mercury was measured in autumn litterfall and weekly precipitation samples at a total of 27 National Atmospheric Deposition Program (NADP) monitoring sites in deciduous and mixed deciduous-coniferous forests in 16 states in the eastern USA during 2007–2014. These simultaneous, uniform, repeated, annual measurements of forest Hg include the broadest area and longest time frame to date. The autumn litterfall-Hg concentrations and litterfall mass at the study sites each year were combined with annual precipitation-Hg data. Rates of litterfall-Hg deposition were higher than or equal to precipitation-Hg deposition rates in 70% of the annual data, which indicates a substantial contribution from litterfall to total atmospheric-Hg deposition. Annual litterfall-Hg deposition in this study had a median of 11.7 μg per square meter per year (μg/m 2 /yr) and ranged from 2.2 to 23.4 μg/m 2 /yr. It closely matched modeled dry-Hg deposition, based on land cover at selected NADP Hg-monitoring sites. Mean annual atmospheric-Hg deposition at forest study sites exhibited a spatial pattern partly explained by statistical differences among five forest-cover types and related to the mapped density of Hg emissions. Forest canopies apparently recorded changes in atmospheric-Hg concentrations over time because litterfall-Hg concentrations decreased year to year and litterfall-Hg concentrations were significantly higher in 2007–2009 than in 2012–2014. These findings reinforce reported decreases in Hg emissions and atmospheric elemental-Hg concentrations during this same time period. Methylmercury (MeHg) was detected in all litterfall samples at all sites, compared with MeHg detections in less than half the precipitation samples at selected sites during the study. These results indicate MeHg in litterfall is a pathway into the terrestrial food web where it can accumulate in the prey of songbirds, bats, and raptors. [ABSTRACT FROM AUTHOR]

This study examined the spatial and temporal trends of mercury (Hg) in wet deposition and air concentrations in the United States (U.S.) and Canada between 1997 and 2013. Data were obtained from the National Atmospheric Deposition Program (NADP) and Environment Canada monitoring networks, and other sources. Of the 19 sites with data records from 1997–2013, 53% had significant negative trends in Hg concentration in wet deposition, while no sites had significant positive trends, which is in general agreement with earlier studies that considered NADP data up until about 2010. However, for the time period 2007–2013 (71 sites), 17% and 13% of the sites had significant positive and negative trends, respectively, and for the time period 2008–2013 (81 sites) 30% and 6% of the sites had significant positive and negative trends, respectively. Non-significant positive tendencies were also widespread. Regional trend analyses revealed significant positive trends in Hg concentration in the Rocky Mountains, Plains, and Upper Midwest regions for the recent time periods in addition to significant positive trends in Hg deposition for the continent as a whole. Sulfate concentration trends in wet deposition were negative in all regions, suggesting a lower importance of local Hg sources. The trend in gaseous elemental Hg from short-term datasets merged as one continuous record was broadly consistent with trends in Hg concentration in wet deposition, with the early time period (1998–2007) producing a significantly negative trend (− 1.5 ± 0.2% year − 1 ) and the recent time period (2008–2013) displaying a flat slope (− 0.3 ± 0.1% year − 1 , not significant). The observed shift to more positive or less negative trends in Hg wet deposition primarily seen in the Central-Western regions is consistent with the effects of rising Hg emissions from regions outside the U.S. and Canada and the influence of long-range transport in the free troposphere. [ABSTRACT FROM AUTHOR]

Annual and weekly mercury (Hg) concentrations, precipitation depths, and Hg wet deposition in the Great Lakes region were analyzed by using data from 5 monitoring networks in the USA and Canada for a 2002–2008 study period. High-resolution maps of calculated annual data, 7-year mean data, and net interannual change for the study period were prepared to assess spatial patterns. Areas with 7-year mean annual Hg concentrations higher than the 12 ng per liter water-quality criterion were mapped in 4 states. Temporal trends in measured weekly data were determined statistically. Monitoring sites with significant 7-year trends in weekly Hg wet deposition were spatially separated and were not sites with trends in weekly Hg concentration. During 2002–2008, Hg wet deposition was found to be unchanged in the Great Lakes region and its subregions. Any small decreases in Hg concentration apparently were offset by increases in precipitation. [Copyright &y& Elsevier]

The Laurentian Great Lakes region of North America contains substantial aquatic resources and mercury-contaminated landscapes, fish, and wildlife. This special issue emanated from a bi-national synthesis of data from monitoring programs and case studies of mercury in the region, here defined as including the Great Lakes, the eight U.S. states bordering the Great Lakes, the province of Ontario, and Lake Champlain. We provide a retrospective overview of the regional mercury problem and summarize new findings from the synthesis papers and case studies that follow. Papers in this issue examine the chronology of mercury accumulation in lakes, the importance of wet and dry atmospheric deposition and evasion to regional mercury budgets, the influence of land–water linkages on mercury contamination of surface waters, the bioaccumulation of methylmercury in aquatic foods webs; and ecological and health risks associated with methylmercury in a regionally important prey fish. [Copyright &y& Elsevier]

Abstract: One of the most critical measurements needed to understand the biogeochemical cycle of mercury, and to verify atmospheric models, is the rate of mercury wet-deposition. The Mercury Deposition Network (MDN) operates sites across North America to monitor total mercury in wet-deposition. MDN''s primary goal is to provide both spatial and temporal continental-scale observations of mercury wet-deposition fluxes to support researchers, modelers, policy-makers and the public interest. MDN represents the only continental-scale mercury deposition database with a >10-year record of continuous values. This study provides analysis and interpretation of MDN observations at 10 years (1996–2005) with an emphasis on investigating whether rigorous, statistically-significant temporal trends and spatial patterns were present and where they occurred. Wet deposition of mercury ranges from more than 25 μg m−2 yr in south Florida to less than 3 μg m−2 yr in northern California. Volume-weighted total mercury concentrations are statistically different between defined regions overall (Southeast ≈ Midwest > Ohio River > Northeast), with the highest in Florida, Minnesota, and several Southwest locations (10–16 ng L−1). Total mercury wet-deposition is significantly different between defined regions (Southeast > Ohio River > Midwest > Northeast). Mercury deposition is strongly seasonal in eastern North America. The average mercury concentration is about two times higher in summer than in winter, and the average deposition is approximately more than three times greater in summer than in winter. Forty-eight sites with validated datasets of five years or more were tested for trends using the non-parametric seasonal Kendall trend test. Significant decreasing mercury wet-deposition concentration trends were found at about half of the sites, particularly across Pennsylvania and extending up through the Northeast. [Copyright &y& Elsevier]

Abstract: A recent analysis [G. Rousseau, D. Gay and M. Piché, One-dimensional description of cylindrically symmetric laser beams: application to Bessel-type nondiffracting beams, J. Opt. Soc. Am. A, 22 (2005) 1274] has shown that any cylindrically symmetric laser beam can be synthesized from a single wave called a constituent wave. This representation allows the introduction of one-dimensional Cartesian root-mean-square (rms) parameters to describe the conical structure of cylindrically symmetric laser beams. In this paper, we compare the rms characterization of Bessel–Gauss beams in polar coordinates with that of their respective constituent waves in Cartesian coordinates. Numerical results reveal an asymptotic correspondence between polar and Cartesian rms parameters of Bessel–Gauss beams propagating in a nondiffracting regime. Such a correspondence eliminates misleading interpretations about the propagation factor and the Rayleigh range of nondiffracting Bessel-type beams characterized in terms of polar rms parameters. [Copyright &y& Elsevier]

Abstract: We have shown that significant reduction of the optical noise can occur in a cw argon ion laser when the laser cavity is coupled to an empty external cavity. When the external cavity was terminated by a phase conjugate mirror, noise reduction reaching 15 dB for the frequency components below 1 MHz and reaching 58 dB at the frequencies of the beating of the longitudinal modes has been observed experimentally. It was also possible to reduce the number of oscillating longitudinal modes from ∼40 to 2 without loss of optical power. A numerical model taking into account the description of the lineshape by a Voigt profile and the presence of an optical feedback has been developed. The numerical results were found to be in good agreement with experimental results. [Copyright &y& Elsevier]

Purpose: To determine the incidence of elbow contracture requiring release after surgically treated elbow trauma and to identify patient, injury, and treatment factors that may predict contracture development. Methods: The New York Statewide Planning and Research Cooperative System database identified 32,708 patients who were surgically treated for elbow trauma from 1997 to 2009. The database identified 270 of those patients who underwent subsequent contracture release. The median time from index fracture procedure to contracture release was 31 weeks. Results: Patients requiring a contracture release were younger (43 vs 56 y) and more commonly male (57%). Injuries classified as severe were more common in the contracture group (11% vs 5%), as were open fractures (17% vs 11%). A multivariate regression analysis revealed that patients with burns were 16 times more likely to require surgical contracture release, and the use of internal fixation to treat the fracture was protective against contracture development. Conclusions: The incidence of elbow contractures treated with release after surgically treated elbow trauma was low but increased with the severity of the initial trauma. Level of evidence: Prognostic II. [Copyright &y& Elsevier]

Ammonia (NH 3 ) emissions and ammonium (NH 4 + ) deposition can have harmful effects on the environment and human health but remain generally unregulated in the U.S. PM 2.5 regulations require that an area not exceed an annual average PM 2.5 value of 12 μg/m 3 (averaged over three years), and since NH 3 is a significant precursor to PM 2.5 formation these are the closest indirect regulations of NH 3 emissions in the U.S. If the U.S. elects to adopt NH 3 emission regulations similar to those applied by the European Union, it will be imperative to first adequately quantify NH 3 emission sources and transport, and also understand the factors causing varying emissions from each source. To further investigate NH 3 emission sources and transport at a regional scale, NH 3 was sampled monthly at a subset of nine Ammonia Monitoring Network (AMoN) sites and analyzed for nitrogen isotopic composition of NH 3 (δ 15 N-NH 3 ). The observed δ 15 N-NH 3 values ranged from −42.4 to +7.1‰ with an average of −15.1 ± 9.7. The observed δ 15 N-NH 3 values reported here provide insight into the spatial and temporal trends of the NH 3 sources that contribute to ambient [NH 3 ] in the U.S. In regions where agriculture is prevalent (i.e., U.S. Midwest), low and seasonally variable δ 15 N-NH 3 values are observed and are associated with varying agricultural sources. In comparison, rural nonagricultural areas have higher and more seasonally consistent δ 15 N-NH 3 values associated with a constant “natural” (e.g. soil, vegetation, bi-directional flux, ocean) NH 3 source. With regards to temporal variation, the peak in U.S. spring agricultural activity (e.g. fertilizer application, livestock waste volatilization) is accompanied by a decrease in δ 15 N-NH 3 values at a majority of the sites, whereas higher δ 15 N-NH 3 values in other seasons could be due to shifting sources (e.g. coal-fired power plants) and/or fractionation scenarios. Fractionation processes that may mask NH 3 source signatures are discussed and require further investigation to optimize the utility of the nitrogen isotopic composition to determine NH 3 sources and dynamics. [ABSTRACT FROM AUTHOR]

Abstract: As many as 51 mercury (Hg) wet-deposition-monitoring sites from 4 networks were operated in 8 USA states and Ontario, Canada in the North American Great Lakes Region from 1996 to 2010. By 2013, 20 of those sites were no longer in operation and approximately half the geographic area of the Region was represented by a single Hg-monitoring site. In response, a Great Lakes Atmospheric Mercury Monitoring (GLAMM) network is needed as a framework for regional collaboration in Hg-deposition monitoring. The purpose of the GLAMM network is to detect changes in regional atmospheric Hg deposition related to changes in Hg emissions. An optimized design for the network was determined to be a minimum of 21 sites in a representative and approximately uniform geographic distribution. A majority of the active and historic Hg-monitoring sites in the Great Lakes Region are part of the National Atmospheric Deposition Program (NADP) Mercury Deposition Network (MDN) in North America and the GLAMM network is planned to be part of the MDN. To determine an optimized network design, active and historic Hg-monitoring sites in the Great Lakes Region were evaluated with a rating system of 21 factors that included characteristics of the monitoring locations and interpretations of Hg data. Monitoring sites were rated according to the number of Hg emissions sources and annual Hg emissions in a geographic polygon centered on each site. Hg-monitoring data from the sites were analyzed for long-term averages in weekly Hg concentrations in precipitation and weekly Hg-wet deposition, and on significant temporal trends in Hg concentrations and Hg deposition. A cluster analysis method was used to group sites with similar variability in their Hg data in order to identify sites that were unique for explaining Hg data variability in the Region. The network design included locations in protected natural areas, urban areas, Great Lakes watersheds, and in proximity to areas with a high density of annual Hg emissions and areas with high average weekly Hg wet deposition. In a statistical analysis, relatively strong, positive correlations in the wet deposition of Hg and sulfate were shown for co-located NADP Hg-monitoring and acid-rain monitoring sites in the Region. This finding indicated that efficiency in regional Hg monitoring can be improved by adding new Hg monitoring to existing NADP acid-rain monitoring sites. Implementation of the GLAMM network design will require Hg-wet-deposition monitoring to be: (a) continued at 12 MDN sites active in 2013 and (b) restarted or added at 9 NADP sites where it is absent in 2013. Ongoing discussions between the states in the Great Lakes Region, the Lake Michigan Air Directors Consortium (a regional planning entity), the NADP, the U.S. Environmental Protection Agency, and the U.S. Geological Survey are needed for coordinating the GLAMM network. [Copyright &y& Elsevier]

Translational regulation impacts both pluripotency maintenance and cell differentiation. To what degree the ribosome exerts control over this process remains unanswered. Accumulating evidence has demonstrated heterogeneity in ribosome composition in various organisms. 2′-O-methylation (2′-O-me) of rRNA represents an important source of heterogeneity, where site-specific alteration of methylation levels can modulate translation. Here, we examine changes in rRNA 2′-O-me during mouse brain development and tri-lineage differentiation of human embryonic stem cells (hESCs). We find distinct alterations between brain regions, as well as clear dynamics during cortex development and germ layer differentiation. We identify a methylation site impacting neuronal differentiation. Modulation of its methylation levels affects ribosome association of the fragile X mental retardation protein (FMRP) and is accompanied by an altered translation of WNT pathway-related mRNAs. Together, these data identify ribosome heterogeneity through rRNA 2′-O-me during early development and differentiation and suggest a direct role for ribosomes in regulating translation during cell fate acquisition. [Display omitted] • rRNA modifications change during mouse brain development and hESC differentiation • Changes to the rRNA methylation profile occur during germ layer specification • Abrogation of methylation at 28S:U3904 impacts the translation of WNT pathway members • Lack of methylation at 28S:U3904 shifts hESCs toward a neurectoderm fate Ribosomes produce one of the main building blocks of living beings—proteins—and exhibit structural variations, such as RNA methylations. Häfner et al. show that some methylations behave dynamically during cell differentiation and that their manipulation impacts cell fate decision-making. [ABSTRACT FROM AUTHOR]

Mexico City Metropolitan Area (MCMA), one of the most populous cities in the world, has historically represented a challenge in terms of air pollution. Particulates and sulfur dioxide. (SO 2) were identified as the main atmospheric pollutants three decades ago. In order to reduce emissions of these pollutants, replacing of fuel oil by natural gas in power plants was carried out in the late 1980s. This strategy resulted in the reduction of ambient air concentrations of both pollutants. SO 2 no longer exceeds its ambient air quality standard; however, acid rain remains a significant issue, with sulfate remaining as the principal component in the wet atmospheric deposition. In this study, spatial and temporal variations in the chemical composition of precipitation (sulfate and nitrate ions, and pH) were obtained weekly at 16 sampling stations, as well as atmospheric SO 2 and nitrogen oxides (NOx) from an air quality monitoring network from 2003 to 2018 in the MCMA. Some indicators were applied to evaluate wet atmospheric deposition: SO 4 2−/NO 3 − and NH 4 +/NO 3 − ratios, fractional acidity as well as neutralization factors. SO 2 ambient air concentrations have decreased from 2003 to 2018 by more than 70%, while NO x has decreased by 20%. The SO 2 /NOx ratio has declined about 60%, indicating more effective strategies in reducing SO 2 than for NOx emissions. The NOx emission sources are more diverse than for SO 2 , and NOx has more complex mechanisms of atmospheric deposition and photochemistry. The pH values of the samples at the stations located in the south were more acidic than the samples for the stations in the north. This result is in line with meteorological conditions, where prevailing winds blow from north to south, as well as emission sources located in the north sector, both inside and outside MCMA. For SO 4 2−/NO 3 − ratio, all sampling sites present current values in the same magnitude order, around 1.4, which is higher compared with urban sites in USA. The 2018 NH 4 +/NO 3 − ratio was 1.98 for the southern sampling site, while all northern sampling sites were approximately 2.28. These results are on the same order that urban sites in USA. It was concluded that ammonium was a very important neutralizing agent of pH within the MCMA precipitation. It is recommended to apply strategies for the emissions reduction of acid rain precursors in external sources to the North the MCMA, and to establish a Network for Urban Atmospheric Nitrogen Chemistry. [Display omitted] • Control strategies applied at Mexico City have achieved an important improvement in SO 2 air quality. • SO 4 2− continues to be the largest component anion of wet atmospheric deposition. • Apply strategies to reduce SO 2 emissions in sources located upwind and outside of Mexico City is needed. • NH 4 + stands out as the major ion in the chemical composition of precipitation and in the case of the inorganic N compounds. • Network for Urban Atmospheric Nitrogen Chemistry at Mexico City, as well as a critical loads research agenda, are needed. [ABSTRACT FROM AUTHOR]

Objectives To assess the capability of digital tomosynthesis (DTS) of the chest compared to a postero-anterior (PA) and lateral chest radiograph (CXR) in the diagnosis of suspected but unconfirmed pulmonary nodules and hilar lesions detected on a CXR. Computed tomography (CT) was used as the reference standard. Materials and method 78 patients with suspected non-calcified pulmonary nodules or hilar lesions on their CXR were included in the study. Two radiologists, blinded to the history and CT, prospectively analysed the CXR (PA and lateral) and the DTS images using a picture archiving and communication workstation and were asked to designate one of two outcomes: true intrapulmonary lesion or false intrapulmonary lesion. A CT of the chest performed within 4 weeks of the CXR was used as the reference standard. Inter-observer agreement and time to report the modalities were calculated for CXR and DTS. Results There were 34 true lesions confirmed on CT, 12 were hilar lesions and 22 were peripheral nodules. Of the 44 false lesions, 37 lesions were artefactual or due to composite shadow and 7 lesions were real but extrapulmonary simulating non-calcified intrapulmonary lesions. The PA and lateral CXR correctly classified 39/78 (50%) of the lesions, this improved to 75/78 (96%) with DTS. The sensitivity and specificity was 0.65 and 0.39 for CXR and 0.91 and 1 for DTS. Based on the DTS images, readers correctly classified all the false lesions but missed 3/34 true lesions. Two of the missed lesions were hilar in location and one was a peripheral nodule. All three missed lesions were incorrectly classified on DTS as composite shadow. Conclusions DTS improves diagnostic confidence when compared to a repeat PA and lateral CXR in the diagnosis of both suspected hilar lesions and pulmonary nodules detected on CXR. DTS is able to exclude most peripheral pulmonary nodules but caution and further studies are needed to assess its ability to exclude hilar lesions. [ABSTRACT FROM AUTHOR]

In this study, the potential sources, scavenging processes, and emission regions for Hg in wet deposition were investigated in rural (Jeju), suburban (Gwangju), and urban sites (Incheon and Seoul) of South Korea. The annual volume-weighted mean concentrations of Hg in wet deposition were four to five times higher in Incheon (16.6 ng L−1) and Seoul (22.5 ng L−1) than in Jeju (4.0 ng L−1) and Gwangju (4.1 ng L−1). The variations in the Hg concentrations in wet deposition of Jeju and Gwangju were related to Cl−, Na+, Mg2+, and K+ originating from marine and crustal sources, and those in Incheon and Seoul were related to SO 4 2−, NO 3 −, and NH 4 + emitted from anthropogenic sources. The below-cloud scavenging was considered a major inclusion process of Hg in Jeju and Gwangju, while the within-cloud scavenging was suggested in Incheon and Seoul, based on the results of correlation analysis with Hg and major ions in wet deposition, and meteorological data. The cluster analysis of backward trajectories demonstrated that the Hg concentration in wet deposition was highest in the cluster transported from Hebei and Shandong of China in Gwangju, but in Seoul, the Hg concentrations of each cluster were comparable. This suggests that regional transport is the major source of Hg in the wet deposition of Gwangju while local transport provides substantial amount of Hg in the wet deposition of Seoul. This was further supported by the results of concentration-weighted trajectories: the most probable source region was east China for Gwangju, and the mid-west of South Korea and east China for Seoul. It is noted that the peak methylmercury concentrations were found every spring with simultaneous increases in atmospheric Al, Ca, Mg, and Fe concentrations, indicating a concurrence with Asian dust. The formation process of methylmercury in Asian dust should be confirmed in future studies. Unlabelled Image • Scavenging processes and source regions of Hg in wet deposition were assessed. • Below-cloud scavenging of regional Hg was prevalent in Jeju and Gwangju. • In-cloud scavenging of local Hg was dominant in Incheon and Seoul. • CWT projected east China as the major source region of Hg in Gwangju. • CWT projected mid-west Korea and east China as the source region of Hg in Seoul. [ABSTRACT FROM AUTHOR]

• The Gulf of Mexico region has important sources of acid rain precursors. • The pH values at Mexican sampling site were similar to the U.S. sites. • At the Mexican site, SO 4 2 - / NO 3 - ratio was higher than in the U.S. sites. • Acidic deposition has a major contribution from the SO 2 emission sources. • It is necessary to extend the atmospheric deposition sampling to other sites. The Gulf of Mexico region has important sources of acid rain precursors, located in all of the countries; U.S., Mexico and Cuba, and so it is very important to study the chemical composition of the wet atmospheric deposition in all coastal areas. For many years along the U.S. Gulf Coast, acidic precipitation has been measured. Measurements along the Mexican Gulf Coast were begun in 2003. The aim of this study was to evaluate pH, sulfate, nitrate and ammonium concentrations in wet atmospheric deposition, collected daily from 2003 to 2015 at La Mancha (LM), Veracruz and compare the values with the National Atmospheric Deposition Program (NADP) sampling sites located along the U.S. coast of the Gulf of Mexico. The annual Volume Weighted Mean (VWM) pH in wet deposition at La Mancha site ranged from 4.81 to 5.40, which is similar to the U.S. Gulf sites. Additionally, the annual VWM SO 4 2 - concentration was from 15 to 31 μeq/L, which is higher than the U.S. sites. Annual VWM NO 3 - concentrations were from of 3.5 to 15 μeq/L, which is lower than all the U.S. sites. At the Mexican site, the SO 4 2 - / NO 3 - ratio was 4.90 and higher than all of the U.S. sites, which were between 1.03 and 2.38. For LM, the median NH 4 +/ NO 3 - ratio was 0.77, similar to the Florida sites (0.53–0.91), and below the values measured for Louisiana and Texas (1.07–1.5). The Hybrid Single Particle Lagrangian Integrated Trajectory Model (HYSPLIT) was applied in order to identify the emission sources for the pollutants seen at LM. Trajectories showed an important transport to LM from the East (open water) during the rainy season. The region located East of La Mancha shows offshore petroleum operations as sources of acid rain precursors and deposition of acidifying and nitrogen containing compounds. It is important to consider the sulfur dioxide emission sources in the Mexico Gulf region, and to extend the atmospheric deposition sampling to other sites along the Mexican Gulf coast and Cuba. [ABSTRACT FROM AUTHOR]