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1.
Environ Monit Assess ; 194(2): 62, 2022 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-34993664

RESUMO

Nine metals including Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn were analysed from sediment samples collected from 29 stations since 2007 from Bahraini waters. Within this study, it was investigated whether concentrations of these determinants are at concentrations above internationally established Assessment Criteria (AC). The majority of sites were considered not to pose a toxicological risk in terms of metal contamination. Where breaches occurred, they were mainly from historic samples related to Cr, Cu and Ni contamination. A trend assessment revealed that out of 59 significant trends, 36 were downwards and 23 upwards, indicating that some determinants like Al, Zn and Ni are improving strongly across some sites, whilst areas associated with industrial activity still see some increasing trends for Al, Cd, Pb and Zn.


Assuntos
Metais Pesados , Poluentes Químicos da Água , Barein , Monitoramento Ambiental , Sedimentos Geológicos , Metais Pesados/análise , Poluentes Químicos da Água/análise
2.
Nat Food ; 3(2): 169-178, 2022 02.
Artigo em Inglês | MEDLINE | ID: mdl-37117966

RESUMO

Intricate links between aquatic animals and their environment expose them to chemical and pathogenic hazards, which can disrupt seafood supply. Here we outline a risk schema for assessing potential impacts of chemical and microbial hazards on discrete subsectors of aquaculture-and control measures that may protect supply. As national governments develop strategies to achieve volumetric expansion in seafood production from aquaculture to meet increasing demand, we propose an urgent need for simultaneous focus on controlling those hazards that limit its production, harvesting, processing, trade and safe consumption. Policies aligning national and international water quality control measures for minimizing interaction with, and impact of, hazards on seafood supply will be critical as consumers increasingly rely on the aquaculture sector to supply safe, nutritious and healthy diets.

3.
Mar Pollut Bull ; 165: 112118, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33582422

RESUMO

Water Quality issues in many Pacific countries are rising, with the increase in coastal populations and associated urban runoff but management requires contamination issues in the aquatic environment to be identified and prioritised. In Vanuatu and Solomon Islands there are few laboratories and resources to assess for the presence or impact of complex chemical contaminants. The extent and impact of chemical contamination of the marine and coastal environment is poorly described. Passive chemical samplers were used to measure a range of aquatic pollutants around the capital cities, Honiara (Solomon Islands) and Port Vila (Vanuatu). We detected a range of chemicals indicative of agricultural and industrial contamination and a few sites had concerning concentrations of specific hydrocarbons and pesticides. The rapid ecotoxicology test, Microtox, indicated toxic impacts in rivers, coastal sites and urban drains This work provides new data on chemical contamination and possible impacts of that contamination for both countries. The techniques could be applied widely across the region to generate critical data for environmental management, guide monitoring efforts and measure the impact of policy or land-use changes.


Assuntos
Praguicidas , Poluentes Químicos da Água , Monitoramento Ambiental , Melanesia , Praguicidas/análise , Vanuatu , Poluentes Químicos da Água/análise , Qualidade da Água
4.
Mar Pollut Bull ; 163: 111915, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33360724

RESUMO

The tropical waters of the Northern Arabian Gulf have a long history of maritime resource richness. High levels of biodiversity result from the complex matrix of coastal habitats, coral reefs and sea grass beds that characterise the region. Insight into the ongoing health of such habitats and the broader Kuwait maritime environment can be gauged by the status of indicator species found within these habitats. Here we review information on the occurrence, distribution and threats to key marine habitats and associated indicator species to provide an updated assessment of the state of the Kuwait's marine biodiversity. Critical evaluation of historic data highlights knowledge gaps needed inform the focus of future monitoring and conservation efforts. This assessment is designed to evaluate performance against environmental policy commitments, while providing a solid foundation for the design of comprehensive marine ecosystem management strategies.


Assuntos
Conservação dos Recursos Naturais , Ecossistema , Biodiversidade , Recifes de Corais , Kuweit
5.
Mar Pollut Bull ; 155: 111099, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32469758

RESUMO

This paper presents a review around seagrass habitat in Tarawa Lagoon, Kiribati and explores the links between seagrass occurrence and the national priority issues of climate change, urban development, human health, nearshore fisheries, threatened species, ocean policy, research capacity and awareness. The contribution of healthy seagrass habitats to many aspects of these national issues is often overlooked and there is need to establish the knowledge gaps and priority actions that can enable mitigation of issues that impact on valuable seagrass resources and their management. Research data on seagrass habitats in Kiribati, and the wider Pacific Island region, is limited and this hinders informed decisions at local, national and regional levels. We present a comprehensive review on seagrass within a national context to aid prioritisation and uptake of information for resource owners, and wider stakeholders, in Kiribati while acknowledging local expertise. The paper highlights data and knowledge gaps that if addressed, will provide information useful to Kiribati nationals, communities and government stakeholders. Recommendations for actions that fill these gaps and build understanding of seagrass resources in Kiribati are provided.


Assuntos
Ecossistema , Pesqueiros , Mudança Climática , Humanos , Micronésia , Ilhas do Pacífico
6.
Nat Food ; 1(8): 468-474, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37128071

RESUMO

Aquaculture is predicted to supply the majority of aquatic dietary protein by 2050. For aquaculture to deliver significantly enhanced volumes of food in a sustainable manner, appropriate account needs to be taken of its impacts on environmental integrity, farmed organism health and welfare, and human health. Here, we explore increased aquaculture production through the One Health lens and define a set of success metrics - underpinned by evidence, policy and legislation - that must be embedded into aquaculture sustainability. We provide a framework for defining, monitoring and averting potential negative impacts of enhanced production - and consider interactions with land-based food systems. These metrics will inform national and international science and policy strategies to support improved aquatic food system design.

7.
Bone Rep ; 8: 204-214, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29955639

RESUMO

The effects of obesity on bone metabolism are complex, and may be mediated by consumption of a high fat diet and/or by obesity-induced metabolic dysregulation. To test the hypothesis that both high fat (HF) diet and diet-induced metabolic disease independently decrease skeletal acquisition, we compared effects of HF diet on bone mass and microarchitecture in two mouse strains: diet-induced obesity (DIO)-susceptible C57BL/6J (B6) and DIO-resistant FVB/NJ (FVB). At 3 wks of age we weaned 120 female FVB and B6 mice onto normal (N, 10% Kcal/fat) or HF diet (45% Kcal/fat) and euthanized them at 6, 12 and 20 weeks of age (N = 10/grp). Outcomes included body mass; percent fat and whole-body bone mineral density (WBBMD, g/cm2) via DXA; cortical and trabecular bone architecture at the midshaft and distal femur via µCT; and marrow adiposity via histomorphometry. In FVB HF, body mass, percent body fat, WBBMD and marrow adiposity did not differ vs. N, but trabecular bone mass was lower at 6 wks of age only (p < 0.05), cortical bone geometric properties were lower at 12 wks only, and bone strength was lower at 20 wks of age only in HF vs. N (p < 0.05). In contrast, B6 HF had higher body mass, percent body fat, and leptin vs. N. B6 HF also had higher WBBMD (p < 0.05) at 9 and 12 wks of age but lower distal femur trabecular bone mass at 12 wks of age, and lower body mass-adjusted cortical bone properties at 20 wks of age compared to N (p < 0.05). Marrow adiposity was also markedly higher in B6 HF vs. N. Overall, HF diet negatively affected bone mass in both strains, but was more deleterious to trabecular bone microarchitecture and marrow adiposity in B6 than in FVB mice. These data suggest that in addition to fat consumption itself, the metabolic response to high fat diet independently alters skeletal acquisition in obesity.

8.
Clin Obes ; 7(6): 384-392, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-28841271

RESUMO

Limited data are available on the characteristics of adolescents with obesity who seek bariatric surgery. Existing data suggest that adolescent surgery candidates have a higher body mass index (BMI) than comparison adolescents with obesity, but the limited findings regarding psychosocial functioning are mixed. This study aimed to compare BMI and psychosocial functioning among adolescent bariatric surgery candidates, outpatient medical-treatment-seeking adolescents with obesity (receiving lifestyle modification), and adolescents in the normal-weight range. All adolescents completed self-report measures of impulsivity, delay discounting, depression, anxiety, stress, eating pathology, family functioning and quality of life, and had their height and weight measured. Adolescent surgical candidates had higher BMIs than both comparison groups. Surgical candidates did not differ from medical-treatment-seeking adolescents with obesity on any measure of psychosocial functioning, but both groups of adolescents with obesity reported greater anxiety and eating pathology and poorer quality of life than normal-weight adolescents. Quality of life no longer differed across groups after controlling for BMI, suggesting that it is highly related to weight status. Adolescents with obesity may experience greater anxiety, eating pathology, and quality of life impairments than their peers in the normal-weight range regardless of whether they are seeking surgery or outpatient medical treatment. Clinical implications and directions for future research are discussed.


Assuntos
Obesidade/psicologia , Obesidade/cirurgia , Adolescente , Ansiedade , Cirurgia Bariátrica , Índice de Massa Corporal , Estudos de Casos e Controles , Criança , Feminino , Humanos , Masculino , Obesidade/fisiopatologia , Obesidade/terapia , Qualidade de Vida , Inquéritos e Questionários
10.
Mar Pollut Bull ; 120(1-2): 422-427, 2017 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-28483143

RESUMO

Nine trace elements including As, Cd, Cu, Fe, Hg, Ni, Pb, V and Zn, and total petroleum hydrocarbons were analysed from water samples collected from 23 stations since 1984 from Kuwaiti coastal waters. Here it was investigated whether concentrations of these determinants are at levels above Kuwaiti and internationally established assessment criteria (AC). The results indicate that Cu and Cd had the most Kuwaiti AC breaches over time. Comparing the data of the last sampled year to the least stringent international AC, then Cu and Cd showed breaches at all stations. The trends for trace metals are significantly downwards, especially for Cd and Hg. No determinant measured showed a significant upward trend, indicating that water pollution for these contaminants is not a worsening situation. However, further sampling should be carried out to confirm these findings, especially at shoreline locations, where routine monitoring ceased in 2011 to investigate any recent changes.


Assuntos
Hidrocarbonetos/análise , Poluentes Químicos da Água/análise , Monitoramento Ambiental , Kuweit , Metais Pesados , Petróleo , Risco , Água do Mar , Oligoelementos
11.
Mon Not R Astron Soc ; 464(1): 968-984, 2017 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32753768

RESUMO

We present multi-wavelength detections of nine candidate gravitationally-lensed dusty star-forming galaxies (DSFGs) selected at 218GHz (1.4mm) from the ACT equatorial survey. Among the brightest ACT sources, these represent the subset of the total ACT sample lying in Herschel SPIRE fields, and all nine of the 218GHz detections were found to have bright Herschel counterparts. By fitting their spectral energy distributions (SEDs) with a modified blackbody model with power-law temperature distribution, we find the sample has a median redshift of z = 4.1 - 1.0 + 1.1 (68 per cent confidence interval), as expected for 218GHz selection, and an apparent total infrared luminosity of log 10 ( µ L IR / L ⊙ ) = 13.86 - 0.30 + 0.33 , which suggests that they are either strongly lensed sources or unresolved collections of unlensed DSFGs. The effective apparent diameter of the sample is µ d = 4.2 - 1.0 + 1.7 kpc , further evidence of strong lensing or multiplicity, since the typical diameter of dusty star-forming galaxies is 1.0-2.5 kpc. We emphasize that the effective apparent diameter derives from SED modelling without the assumption of optically thin dust (as opposed to image morphology). We find that the sources have substantial optical depth. ( τ = 4.2 - 1.9 + 3.7 ) to dust around the peak in the modified blackbody spectrum (λ obs ⩽ 500µm), a result that is robust to model choice.

12.
J Endocrinol ; 229(3): 295-306, 2016 06.
Artigo em Inglês | MEDLINE | ID: mdl-27340200

RESUMO

Starvation induces low bone mass and high bone marrow adiposity in humans, but the underlying mechanisms are poorly understood. The adipokine leptin falls in starvation, suggesting that hypoleptinemia may be a link between negative energy balance, bone marrow fat accumulation, and impaired skeletal acquisition. In that case, treating mice with leptin during caloric restriction (CR) should reduce marrow adipose tissue (MAT) and improve bone mass. To test this hypothesis, female C57Bl/6J mice were fed a 30% CR or normal (N) diet from 5 to 10 weeks of age, with daily injections of vehicle (VEH), 1mg/kg leptin (LEP1), or 2mg/kg leptin (LEP2) (N=6-8/group). Outcomes included body mass, body fat percentage, and whole-body bone mineral density (BMD) via peripheral dual-energy X-ray absorptiometry, cortical and trabecular microarchitecture via microcomputed tomography (µCT), and MAT volume via µCT of osmium tetroxide-stained bones. Overall, CR mice had lower body mass, body fat percentage, BMD, and cortical bone area fraction, but more connected trabeculae, vs N mice (P<0.05 for all). Most significantly, although MAT was elevated in CR vs N overall, leptin treatment blunted MAT formation in CR mice by 50% vs VEH (P<0.05 for both leptin doses). CR LEP2 mice weighed less vs CR VEH mice at 9-10 weeks of age (P<0.05), but leptin treatment did not affect body fat percentage, BMD, or bone microarchitecture within either diet. These data demonstrate that once daily leptin bolus during CR inhibits bone marrow adipose expansion without affecting bone mass acquisition, suggesting that leptin has distinct effects on starvation-induced bone marrow fat formation and skeletal acquisition.


Assuntos
Tecido Adiposo/efeitos dos fármacos , Medula Óssea/efeitos dos fármacos , Restrição Calórica/efeitos adversos , Leptina/administração & dosagem , Adiposidade/efeitos dos fármacos , Animais , Densidade Óssea/efeitos dos fármacos , Osso e Ossos/diagnóstico por imagem , Osso e Ossos/efeitos dos fármacos , Metabolismo Energético/efeitos dos fármacos , Feminino , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Proteínas Recombinantes/administração & dosagem , Microtomografia por Raio-X
13.
Mar Pollut Bull ; 100(2): 607-20, 2015 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-26490407

RESUMO

This work analyses a 30 year water quality data set collated from chemical analyses of Kuwait's marine waters. Spatial patterns across six sites in Kuwait Bay and seven sites located in the Arabian Gulf are explored and discussed in terms of the changing influences associated with point and diffuse sources. Statistical modelling demonstrated significant increases for dissolved nutrients over the time period. Kuwait marine waters have been subject to inputs from urban development, untreated sewage discharges and decreasing river flow from the Shatt al-Arab River. Chlorophyll biomass showed a small but significant reduction; the high sewage content of the coastal waters from sewage discharges likely favouring the presence of smaller phytoplankton taxa. This detailed assessment of temporal data of the impacts of sewage inputs into Kuwait's coastal waters establishes an important baseline permitting future assessments to be made as sewage is upgraded, and the river continues to be extracted upstream.


Assuntos
Água do Mar/química , Qualidade da Água , Biomassa , Clorofila/análise , Meio Ambiente , Monitoramento Ambiental/métodos , Kuweit , Modelos Estatísticos , Fitoplâncton/crescimento & desenvolvimento , Rios , Esgotos/análise , Urbanização
14.
Mar Pollut Bull ; 100(2): 681-8, 2015 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-26478454

RESUMO

Kuwait is a country with low rainfall and highly concentrated industrial and domestic effluents entering its coastal waters. These can be both treated and untreated. In this study we sampled a series of coastal and open-sea sites and used a variety of analyses to identify those sites requiring the most attention. We used a high throughput GC-MS screen to look for over 1000 chemicals in the samples. Estrogen and androgen screens assessed the potential to disrupt endocrine activity. An oyster embryo development screen was used to assess biological effect potential. The chemical screen identified sites which had high numbers of identified industrial and domestic chemicals. The oyster screen showed that these sites had also caused high levels of developmental abnormalities with 100% of embryos affected at some sites. The yeast screen showed that estrogenic chemicals were present in outfalls at 2-3 ng/l E2 equivalent, and detectable even in some open water sites.


Assuntos
Ecotoxicologia/métodos , Disruptores Endócrinos/análise , Monitoramento Ambiental/métodos , Poluentes Químicos da Água/análise , Poluição da Água/análise , Animais , Crassostrea/efeitos dos fármacos , Crassostrea/embriologia , Embrião não Mamífero/efeitos dos fármacos , Disruptores Endócrinos/toxicidade , Sistema Endócrino/efeitos dos fármacos , Cromatografia Gasosa-Espectrometria de Massas/métodos , Kuweit , Poluentes Químicos da Água/toxicidade
15.
Mar Pollut Bull ; 100(2): 629-36, 2015 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-26344820

RESUMO

A geographically extensive baseline survey of sediment contamination was undertaken at twenty nine locations around Kuwait. Samples were assessed in relation to a wide range of industrial pollutants, including metals, PAHs, PCBs, PBDEs and HBCDs. The data generated indicated that levels of pollutants were generally low and below commonly applied sediment quality guidelines (SQGs). However, naturally high background concentrations of certain metals present in sediment from the region may prohibit the direct assessment against some of the routinely applied SQGs. Hot spots of contamination were identified for PAHs, PCBs and PBDEs, that were mainly associated with the Shuaiba Industrial Area, located south of the city, and known to contain a diverse mix of both light and heavy industry.


Assuntos
Retardadores de Chama/análise , Sedimentos Geológicos/análise , Metais/análise , Bifenilos Policlorados/análise , Poluentes Químicos da Água/análise , Cidades , Monitoramento Ambiental , Éteres Difenil Halogenados/análise , Kuweit , Oceanos e Mares , Hidrocarbonetos Policíclicos Aromáticos/análise , Inquéritos e Questionários
16.
Mar Pollut Bull ; 100(2): 689-98, 2015 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-26228071

RESUMO

Microbial water quality and concentrations of faecal sterols in sediment have been used to assess the degree of sewage contamination in Kuwait's marine environment. A review of microbial (faecal coliform, faecal streptococci and Escherichia coli) water quality data identified temporal and spatial sources of pollution around the coastline. Results indicated that bacterial counts regularly breach regional water quality guidelines. Sediments collected from a total of 29 sites contained detectable levels of coprostanol with values ranging from 29 to 2420 ng g(-1) (dry weight). Hot spots based on faecal sterol sediment contamination were identified in Doha Bay and Sulaibikhat Bay, which are both smaller embayments of Kuwait Bay. The ratio of epicoprostanol/coprostanol indicates that a proportion of the contamination was from raw or partially treated sewage. Sewage pollution in these areas are thought to result from illegal connections and discharges from storm drains, such as that sited at Al-Ghazali.


Assuntos
Esgotos , Esteróis/análise , Microbiologia da Água , Qualidade da Água , Baías , Colestanol/análise , Colestanóis/análise , Enterobacteriaceae , Escherichia coli/isolamento & purificação , Fezes/química , Sedimentos Geológicos/química , Sedimentos Geológicos/microbiologia , Kuweit , Esgotos/análise , Streptococcus/isolamento & purificação , Poluição da Água/análise
17.
Endocrinology ; 155(10): 3806-16, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-25051433

RESUMO

Type 2 diabetes (T2D) incidence in adolescents is rising and may interfere with peak bone mass acquisition. We tested the effects of early-onset T2D on bone mass, microarchitecture, and strength in the TALLYHO/JngJ mouse, which develops T2D by 8 weeks of age. We assessed metabolism and skeletal acquisition in male TALLYHO/JngJ and SWR/J controls (n = 8-10/group) from 4 weeks to 8 and 17 weeks of age. Tallyho mice were obese; had an approximately 2-fold higher leptin and percentage body fat; and had lower bone mineral density vs SWR at all time points (P < .03 for all). Tallyho had severe deficits in distal femur trabecular bone volume fraction (-54%), trabecular number (-27%), and connectivity density (-82%) (P < .01 for all). Bone formation was higher in Tallyho mice at 8 weeks but lower by 17 weeks of age vs SWR despite similar numbers of osteoblasts. Bone marrow adiposity was 7- to 50-fold higher in Tallyho vs SWR. In vitro, primary bone marrow stromal cell differentiation into osteoblast and adipocyte lineages was similar in SWR and Tallyho, suggesting skeletal deficits were not due to intrinsic defects in Tallyho bone-forming cells. These data suggest the Tallyho mouse might be a useful model to study the skeletal effects of adolescent T2D.


Assuntos
Desenvolvimento Ósseo , Diabetes Mellitus Tipo 2/fisiopatologia , Fatores Etários , Idade de Início , Animais , Densidade Óssea/efeitos dos fármacos , Densidade Óssea/genética , Desenvolvimento Ósseo/efeitos dos fármacos , Desenvolvimento Ósseo/genética , Células Cultivadas , Diabetes Mellitus Experimental/genética , Diabetes Mellitus Experimental/fisiopatologia , Diabetes Mellitus Tipo 2/genética , Dieta Hiperlipídica , Sacarose Alimentar/farmacologia , Masculino , Camundongos , Camundongos Mutantes , Camundongos Obesos , Osteogênese/fisiologia
18.
J Endocrinol ; 217(1): 69-81, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-23503967

RESUMO

Maternal high-fat (HF) diet can alter offspring metabolism via perinatal developmental programming. This study tests the hypothesis that maternal HF diet also induces perinatal programming of offspring bone mass and strength. We compared skeletal acquisition in pups from C57Bl/6J mice fed HF or normal diet from preconception through lactation. Three-week-old male and female pups from HF (HF-N) and normal mothers (N-N) were weaned onto normal diet. Outcomes at 14 and 26 weeks of age included body mass, body composition, whole-body bone mineral content (WBBMC) via peripheral dual-energy X-ray absorptiometry, femoral cortical and trabecular architecture via microcomputed tomography, and glucose tolerance. Female HF-N had normal body mass and glucose tolerance, with lower body fat (%) but higher serum leptin at 14 weeks vs. N-N (P<0.05 for both). WBBMC was 12% lower at 14 weeks and 5% lower at 26 weeks, but trabecular bone volume fraction was 20% higher at 14 weeks in female HF-N vs. N-N (P<0.05 for all). Male HF-N had normal body mass and mildly impaired glucose tolerance, with lower body fat (%) at 14 weeks and lower serum leptin at 26 weeks vs. N-N (P<0.05 for both). Serum insulin was higher at 14 weeks and lower at 26 weeks in HF-N vs. N-N (P<0.05). Trabecular BV/TV was 34% higher and cortical bone area was 6% higher at 14 weeks vs. N-N (P<0.05 for both). These data suggest that maternal HF diet has complex effects on offspring bone, supporting the hypothesis that maternal diet alters postnatal skeletal homeostasis.


Assuntos
Desenvolvimento Ósseo , Osso e Ossos/patologia , Dieta Hiperlipídica/efeitos adversos , Lactação , Fenômenos Fisiológicos da Nutrição Materna , Sobrepeso/fisiopatologia , Complicações na Gravidez/fisiopatologia , Animais , Densidade Óssea , Osso e Ossos/química , Osso e Ossos/diagnóstico por imagem , Feminino , Desenvolvimento Fetal , Intolerância à Glucose/sangue , Intolerância à Glucose/congênito , Intolerância à Glucose/etiologia , Intolerância à Glucose/fisiopatologia , Leptina/sangue , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Minerais/análise , Sobrepeso/etiologia , Gravidez , Complicações na Gravidez/etiologia , Radiografia , Índice de Gravidade de Doença , Caracteres Sexuais
19.
Appl Opt ; 52(36): 8747-58, 2013 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-24513939

RESUMO

The increasing scale of cryogenic detector arrays for submillimeter and millimeter wavelength astrophysics has led to the need for large aperture, high index of refraction, low loss, cryogenic refracting optics. Silicon with n=3.4, low loss, and high thermal conductivity is a nearly optimal material for these purposes but requires an antireflection (AR) coating with broad bandwidth, low loss, low reflectance, and a matched coefficient of thermal expansion. We present an AR coating for curved silicon optics comprised of subwavelength features cut into the lens surface with a custom three-axis silicon dicing saw. These features constitute a metamaterial that behaves as a simple dielectric coating. We have fabricated silicon lenses as large as 33.4 cm in diameter with micromachined layers optimized for use between 125 and 165 GHz. Our design reduces average reflections to a few tenths of a percent for angles of incidence up to 30° with low cross polarization. We describe the design, tolerance, manufacture, and measurements of these coatings and present measurements of the optical properties of silicon at millimeter wavelengths at cryogenic and room temperatures. This coating and lens fabrication approach is applicable from centimeter to submillimeter wavelengths and can be used to fabricate coatings with greater than octave bandwidth.

20.
Mar Pollut Bull ; 65(4-9): 224-35, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22469152

RESUMO

The extent of flood plume water over a 10 year period was mapped using quasi-true colour imagery and used to calculate long-term frequency of occurrence of the plumes. The proportional contribution of riverine loads of dissolved inorganic nitrogen, total suspended sediments and Photosystem-II herbicides from each catchment was used to scale the surface exposure maps for each pollutant. A classification procedure was also applied to satellite imagery (only Wet Tropics region) during 11 flood events (2000-2010) through processing of level-2 ocean colour products to discriminate the changing characteristics across three water types: "primary plume water", characterised by high TSS values; "secondary plume water", characterised by high phytoplankton production as measured by elevated chlorophyll-a (chl-a), and "tertiary plume water", characterised by elevated coloured dissolved and detrital matter (CDOM+D). This classification is a first step to characterise flood plumes.


Assuntos
Monitoramento Ambiental/métodos , Inundações/estatística & dados numéricos , Rios/química , Poluentes Químicos da Água/análise , Austrália , Clorofila/análise , Recifes de Corais , Herbicidas/análise , Fitoplâncton/crescimento & desenvolvimento , Fitoplâncton/fisiologia , Tecnologia de Sensoriamento Remoto , Astronave , Movimentos da Água , Poluição Química da Água/estatística & dados numéricos
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